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THE VAL GRAVEGLIA MANGANESE DISTRICT, LIGURIA, ITALY.

Val Graveglia is the type locality for eight minerals (gravegliaite, medaite, palenzonaite, reppiaite, saneroite, strontiopiemontite, tiragalloite and vanadomalayaite), and is one of the few reported localities for several other rare species including gamagarite, marsturite, nabiasite, haradaite and pyrobelonite. This deposit has also produced exceptional specimens of tinzenite, sursassite and ganophyllite.

INTRODUCTION

Manganese is thc twelfth most abundant clement in the earth's crust. Manganese deposits are generally of sedimentary origin. with oxide ore layers interbedded with iron-rich formations, also as carbonate ore in black carbonaceous shales, and as nodular ores. Nodules and crusts can form in soil profiles along weathering surfaces, in shallow marine sediments and on the deep sea floor. Huge concentrations of manganese are often associated with the so-called sea-floor black smokers, which represent the highest part of hydrothermal systems (Bonatti, 1975).

Manganese has been used in small amounts since antiquity. but not until the 1850's were the valuable properties of manganese in iron and steel metallurgy recognized, and the metal finally used in industrial applications. A huge increase in manganese demand occurred in the second half of the 19th century, and many mines were opened. Today's world demand, mainly from the steel industry, is around 25 million tons per year. Most of the present-day production is from Ukraine and Georgia in the Commonwealth of Independent States, China, and from South Africa, Brazil, Australia, India and Gabon. The largest high-grade ore deposits are located in the South African Republic, accounting for about 80% of the world land reserves (Cairneross et al., 1997).

Manganese deposits are often of great interest from a mineralogical point of view: the peculiar electrochemistry of this element and its geochemical association with other elements such as arsenic, barium, iron, lead, vanadium and zinc play an important role in the formation of many interesting and occasionally fine minerals.

The manganese district of Val Graveglia in northern Italy produced over one million tons of high-grade ore in about a century of operation, reaching a maximum production rate of about 50,000 tons per year. The deposits are rather small, but has yielded to date over 125 mineral species, some of which are remarkable for beauty or rarity.

LOCATION

The northern coastal region of the Tyrrenian Sea is called Liguria: the name is from an ancient people known as the Ligures, who lived in a wide area ranging from northern Italy to the southern part of present-day France. Human occupation there dates back to Paleolithic times and is evidenced by many archeological discoveries. The Romans conquered Liguria in the 2nd century BC, and since that time the region has had a complex history.

Genoa is the main city and the main harbor of the region; the eastern Ligurian coast is famous for its beauty and mild climate, including world-famous localities such as Portofino, Rapallo and Santa Margherita. The area surrounding the towns of Chiavari and Lavagna is called Tigullio, after the Latin word tigellum (tile) because of the abundance of slates, which are used extensively as roof material (Tiscornia, 1935).

The Graveglia Creek, part of the Entella River Basin, is located in the inland Tigullio area, a few kilometers northeast of Lavagna. The Graveglia Valley (in Italian Val Graveglia) covers an area of about 60 square kilometers. The industrial mining of manganese developed there during the 19th century and is continuing today on a very small scale.

HISTORY OF MINING

Human presence in Val Graveglia dates back to the CopperBronze Age, as proven by finds of ancient tools at Monte Bardeneto and Monte Zatta (Ministero per i Beni Culturali ed Ambientali- Soprintendenza Archeologica della Liguria, 1998). The mining history of Liguria began much earlier than the Roman conquest. In eastern Liguria, in particular, several ancient mines are known. At Rocche di Lagorara about 3000 years BC jasper chips were quarried to make tools (Maggi et al., 1988). In the mining complex of Libiola and in the neighboring Monte Loreto area, about 10km from Val Graveglia, stone hammers and other primitive wood mining tools were found (Issel, 1879). Recent analyses based on the [C.sup.14] content on this material have led to the determination of an age of 4580 [+ or -] 45 years BP (Maggi and Pearce, 1997).

In the 7th century BC, Chiavari was the main settlement in a rich mining and quarrying area. Later, during the Roman Empire, the mining activities moved to Gallia and Hispania (for example to the Rio Tinto deposit in present-day Spain). Prospecting for copper, iron, lead, gold and silver resumed on a small scale during the Middle Ages and continued until the 18th century (Pipino, 1984).

In the 18th century the mining operations in Liguria, mainly for copper, grew to industrial scale as a consequence of new technologies, improved communications and new prospecting activity in the area (Issel, 1883). Mining continued, with frequent ups and downs, well into the 1900's. The last workings were closed in the 1950's. The most important mines were located in the Monte Loreto and Libiola areas; in Val Graveglia some copper prospects were opened without leading to any significant mining activity.

During the second half of the 19th century, high manganese prices led to extensive prospecting, and the Val Graveglia deposits were discovered. In 1877 Augusto Fages, a local entrepreneur and pioneer of manganese prospecting, identified the main manganese ore outcrops: Gambatesa, Monte Bossea, Monte Bianco-Cassagna. Molinello near Nascio and Scrava near Statale, all in the Province of Genoa (Tiscornia, 1935). More outcrops were prospected in the Graveglia Valley at Monte Porcile, Balarucca, Nossiglia and Pontori and in some other localities in eastern Liguria as the Tre Monti mining complex, Monte Nero, Cerehiara and Framura.

The ore outcrops in Val Graveglia were the richest and most numerous. Mining began in 1881, and the quantity and quality of ore discovered justified significant industrial investment. During the first years of activity the ore was hand-sorted, mainly by female workers, and carried on mules to the harbor of Lavagna near Chiavari. The high transportation cost hindered the development of mining until 1904 when the mining company built a road from Conscenti to the Pian di Fieno ore treatment plant, aiding the industrial exploitation of the Val Graveglia mines.

Later the mines changed hands and were operated by various companies: from 1919 to 1930 by Societa Ferriere di Voltri, then by lIva (1931-1939), Ferromin (1940-1964) and by the Italsider iron and steel state-controlled industrial group (1965-1974). At that time Italsider also owned the iron mines of Elba and Campiglia in Tuscany and tried, wherever possible, to develop domestic mining resources. The ore production, previously limited to a few hundred to a few thousand tons per year, reached a peak of about 50,000 tons per year in the early 1970's. The manganese ore was used in the iron and steel metallurgy processes at the Italsider Darfo and Lovere plants in Lombardy.

During the Italsider ownership a sink-float ore enrichment plant was built at Pian di Fieno. This plant made it possible to exploit the lower-grade parts of the deposit: the "lean ore," consisting of thin manganese-bearing layers within the jasper. In 1974 Italsider ceased mining operations. The sizable amount of ore in place and the favorable manganese quotations induced some mine employees, including the former mine manager, to establish a new company (Sil.ma.), and in 1976 production was restarted at a reduced rate (a few hundred tons per year) and without using the sink-float technology. During this period most of the rare minerals were collected, including eight new species.

At present all the mines except Gambatesa are closed and the activity there is minimal, but there are plans to transform it into a mining museum.

The total amount of ore mined in the Val Graveglia district is estimated to be over 1,200,000 tons, with a Mn content around 28- 30% (Bellini et al., 1984).

VAL GRAVEGLIA TODAY

The Val Graveglia mines left a deep mark on the environment and on the people of the valley. In the villages of the rocky upper valley, where the farm land is limited, almost all families had members working in the mines. Mine workers numbered 50 to 100 in 1937, then grew to 500 in 1938, to 614 in 1942 and then decreased to 110 in 1974, when large-scale mining activity ceased (Galli and Penco, 1997). Many pits, excavations, mine dumps, some remains of cableways, hoppers, ore treatment plants and roads are still visible and testify to the past of a region which hosted an important manganese deposit.

Exceptional mineral specimen discoveries took place during the years of intense mining activity. During that period nice specimens of tinzenite, sursassite and rhodonite were relatively common, and rare species were also found from time to time. Unfortunately, in those days mineral collectors were few, the interest of the scientific community in the locality was low, and analytical tools were not as developed as they are now.

At present good material is hard to find. The open-cuts of the Gambatesa, Cassagna and Scrava mines are partially covered by recent dumps of waste material, the adits of the abandoned tunnels are closed, and the late 1980's underground works of the Molinello mine are flooded. In theory, the Gambatesa mine is still active, but in practice it produces just a few tons per year. The upper levels of the mine are still under maintenance, but they are not accessible to collectors. It must be remembered that most of the orebody consists of massive braunite, and the minerals hosted in veins and cavities can be recovered much more easily from the broken ore brought out of the mine rather than in situ. Large-scale resumption of mining activity is unlikely, due to the limited remaining extension of the deposit, to the availability of low-cost manganese ore from several other countries, and to the high cost of local labor.

The dumps, widespread around all the Val Graveglia mines, are only partially covered by vegetation. Although fine minerals are not easy to find, the deposit area is wide and the discovery of significant specimens is not unlikely in the future, both in the field and through the examination of material collected in the past. It is sometimes possible to recognize very good specimens of rare species preserved in old collections and misidentified as common species. One of us, for example, observed a sarkinite crystal over 1 cm long once thought to be the more common tinzenite.

GEOLOGY

An ophiolitic suite consisting of ultramafic rocks, usually highly serpentinized and associated with mafic masses, crops out in the Northern Apennines. The upper part of the complex includes breccias containing fragments of ultrabasic, basic and trodhjemitic rocks, and basalts, often with pillow structures (Decandia and Elter, 1972; Cortesogno et al., 1979; Hoogerduijn Strating and Van Wamer, 1989; Societa Geologica Italiana, 1994).

Above the ophiolites is a complex of radiolarian chert and siliceous shale known as the Monte Alpe Chert Formation. The series continues with marls, siliceous shales and pelagic limestone (Calpionella Limestone), and ends with the Palombini Shale and turbiditic units. The ophiolites are believed to be the remnants of some part of the Jurassic oceanic crust, known as the Ligurid Units, which now constitute the structurally highest part of the Apennine chain. Many events leading to the formation of minerals and ores occurred during a geological history of about 100 million years.

The oceanic metamorphic event transformed the gabbros into rodingites, while iron and copper sulfides were deposited by hydrothermal activity. Hot-fluid vents deposited a high concentration of manganese on the Jurassic sea floor, presently appearing as manganese ore deposits within the Monte Alpe Chert formation (Bezzi and Piccardo, 1971).

All the rocks of the series recrystallized under greenschist metamorphic conditions during the alpine orogeny (Cortesogno et al., 1979; Cortesogno and Lucchetti, 1984). The pre-existing sulfides were remobilized and formed Cu-Fe deposits. Moreover, some elements present in low concentrations in the rock mass were concentrated in the rock fractures by fluids (Bonatti et al., 1976). The complexity of the geological and petrologic environment, the abundance of fractures along the shear zones and at the hinge zones of the folds, together with the presence of manganese, vanadium, arsenic and many other elements made possible the formation of many interesting minerals.

In the peridotitic basement rocks a few species are present, such as serpentine-group minerals, magnetite and andradite. In the pillow lava, metamorphosed under greenschist conditions, cavities up to 20 or more centimeters are common, often partially filled by epidote, prehnite and quartz, all of them commonly in good crystals. Calcite, pumpellyite and hematite are also widespread. Along old faulting zones small masses of pyrite (often copper-bearing) are present. These marginal deposits were explored and mined mainly during the 19th century. In the old workings several secondary minerals were found, including nice malachite and allophane.

The radiolarites formation of Monte Alpe is undoubtedly the most mineralogically interesting in the area. In the basal part of the formation the manganese-bearing layers form a banded ore known as "lean manganese ore," which is quite common. The formation of layers of cherts with different silica, iron and manganese contents seems to be related to variations in pH and Eh values at the time of the deposition (De Negri and Rivalenti, 1971; Galli and Penco, 1997). The "lean ore" is sometimes crossed by veins up to 80 cm wide and up to several tens of meters in length; this kind of vein yielded carpholite, native copper, sulfides, and probably the world's best specimens of tinzenite, sursassite and ganophyllite.

The same stratigraphic basal unit of the Monte Alpe Formation also includes the main manganese orebody, formed by braunite layers (Burckhardt and Falini, 1956). The thickest layers, up to 20 meters, are thought to have possibly formed by gravitational accumulation of pre-existing Mn-rich sediments, which were concentrated in paleogeographic depressions. Further increase in thickness occurred in the hinge areas during folding. The braunite ore is relatively rich in veins and vugs containing good specimens of rhodonite, rhodochrosite, tephroite, kutnahorite, pyroxmangite and barite.

In the orebody veins the circulating fluids concentrated elements such as arsenic and vanadium, which formed many minerals, some of which were discovered here for the first time (tiragalloite, medaite, saneroite, palenzonaite, vanadomalayaite, reppiaite) or which are rare or uncommon (haradaite, tangeite, sussexite, gamagarite and goldmanite). The crystallization of the arsenic-bearing and vanadium-bearing minerals could be related to a hydrothermal event taking place under conditions of decreasing temperature with respect to greenschist conditions recognized in the ophiolitic sequence (Basso et al., 1992). The new mineral gravegliaite, a rare natural sulfite, occurs, in secondary suites.

A very peculiar occurrence of minerals in Val Graveglia must also be noted: within the Jurassic-age radiolarites it is sometimes possible to find silicified (petrified) woods belonging to trees of the extinct genus Araucariopitys (Cortesogno and Galli, 1974; Marchesini, 1999). This is an unexpected occurrence; the radiolarites are considered to be equivalent to the present-day muds in the oceanic or marine sea floor, which was not a likely environment for typical continental plants to grow (Calvert, 1971). According to recent studies (Societa Geologica Italiana, 1994; Marescotti, 1993), during the Jurassic period the paleogeography of the area would have been quite complex, and perhaps some islands hosted primitive trees. Some timbers or wood fragments, after floating for some time and distance on the sea surface, may have sunk in the proximity of sea vents, where there was an abundance of dissolved metal ions. This particular environment permitted the preservation of the wood; the pH and Eh conditions cause d the partial replacement of the wood material, and in particular the deposition of native copper or chalcocite in the wood microcavities. Later, during the recrystallization of the rock mass, more minerals formed. Finally, secondary minerals formed. In the fossil wood many mineral species have been found, including copper, chalcocite, volborthite, cornubite, chalcophyllite, zeunerite, connellite and many others. It is interesting that significant amounts of Cu, V, As, Cl and even U probably originated from the hot-water sea vents. This occurrence seems to be specific to eastern Liguria and is not known in the very old manganese deposits, which were formed before the development of trees on earth.

MINES, QUARRIES AND OUTCROPS

Cassagna and Monte Bianco Mines

These are the most important mines in the area (together with Gambatesa and Molinello), with extensive underground workings, excavations and a more recent, large open pit. Some exceptional specimens of rhodonite, tinzenite and rhodochrosite have been found here, as well as remarkable volborthite collected in the 1970's. The operation ceased in 1998.

Gambatesa Mine

Discovered in 1877 by A. Fages, the Gambatesa deposit has been the main source of manganese ore and, perhaps, of interesting minerals. In 1885 (Tiscornia, 1935) some chalcopyrite was discovered in the basalts, but prospecting for copper ore did not yield any significant result. The first manganese ore excavations were open cuts; but later some tens of kilometers of tunnels were excavated. Excellent rhodonite and rhodochrosite specimens were collected, and also very nice sursassite, goldmanite, manganaxinite, tinzenite and neotocite. Gambatesa is the type locality for gravegliaite, saneroite, reppiaite and vanadomalayaite.

Molana Quarry

This stone quarry, presently inactive, was opened in a pillow lava basalt zone near the Molinello mine. Attractive epidote, prehnite and pumpellyite specimens were found during the last years of activity before operations ceased in 1993.

Molinello Mine

The Molinello workings were mainly underground; they yielded fine copper, gamagarite, ganophyllite, rhodochrosite, rhodonite, tangeite and tinzenite specimens. The Molinello mine is the type locality for medaite, palenzonaite and tiragalloite. Operations there ceased in 1996.

Monte Bardeneto-Monte Capra Prospect

Some masses of pyrite and chalcopyrite were mined at this prospect, but with no encouraging results. Some underground workings produced a few hundred tons of ore (Tiscornia, 1935). In the gossan portion of the outcrops nice langite specimens with native copper and cuprite were found. Recent collecting trips to this locality did not yield any good specimens.

Monte Bianco Copper Mine

The Monte Bianco is a small copper mine opened in 1879-80 by the local entrepreneur G. B. Bonelli (Tiscornia, 1935). It produced some pyrite and a few tons of chalcopyrite; no specimens of significance have been collected there to date. On the opposite side of Mount Bianco some native copper, associated with cuprite, connellite and other secondary copper minerals was recently collected in the radiolarites of the Monte Alpe formations.

Monte Bossea Mine

The Monte Bossea is an underground manganese mine whose main adit is near the Molinello mine, on the opposite side of Graveglia Valley. Closed since the end of the Italsider activity, it was not particularly rich in rare species. Good tinzenite veins were encountered in some zones, but vugs were very rare there.

Monte Copello-Reppia Prospect

Along the contact between basalts and serpentinites some small masses of pyrite and chalcopyrite have been found. In the gossan good allophane and malachite specimens were recovered. Mining attempts there have been documented since 1868 (Galli and Penco, 1997; Tiscornia, 1935).

Monte Porcile Mine

Together with the Monte Zenone and Monte Alpe mines, the Monte Porcile mine was included in the so-called Tre Monti manganese claim, filed in 1891 by Augusto Parma. No remarkable mineral finds have been reported to date; nevertheless further investigations might yield results.

Nascio

Nascio is a village near the Molinello mine where some basalt masses crop out. Epidote with orthoclase (adularia variety) and quartz was collected here. Similar specimens were also found at Pontelagoscuro and Zerli though not as abundantly as at Nascio.

Scrava Mine

The Scrava mine consists of extensive, mainly underground manganese mine workings. Generally the ore was rich in carbonates, and calcite and manganoan calcite were common. It yielded good crystals of volborthite, chalcophyllite and other arsenates. In addition, some good pyrolusite crystals were collected there in an oxidized part of the deposit. Operations ceased in 1996.

Pontori Prospect

Some attempts were made to mine manganese ore at the Pontori prospect around 1920. In recent years a few small synchsite-(Ce) and bastnasite-(Ce) specimens have been collected, in association with anatase, quartz, sulfides and albite.

Other localities

Some manganese outcrops are also known at the Val Graveglia localities of Valle Bona, Balarucca and Nossiglia. No significant mineral finds have been reported from those localities, except for braunite and manganese oxides.

Other small manganese deposits in the same general area, although not included in Val Graveglia, should be mentioned here. The first is the Cerchiara mine, located about 30 km to the southeast. This deposit formed in the same basin and is of similar age but is hosted by a thinner chert sequence. Cerchiara is the type locality for mozartite, caoxite and cerchiaraite. Nearby is another small Mn deposit known as the Monte Nero mine; in recent times (late 1990's) good inesite specimens have been collected there (Marchesini and Palenzona, 1997).

COMPARISONS

The Val Graveglia manganese mines have produced some rare and uncommon species (bementite, ganophyllite, sarkinite, sussexite, tephroite etc.) reported from just a few other famous localities, such as Langban, Sweden, and Franklin and Sterling Hill, New Jersey (Holstam and Langhof, 1999; Frondel and Baum, 1974). A number of other localities around the world are known to have produced some of the minerals typical of Val Graveglia. These include the Kombat mine (Namibia), the Kalahari and the Postmasburg deposits (South Africa), some small Alpine manganese deposits such as Praborna near St. Marcel, Val d'Aosta (in the western Italian Alps) and Scerscen, Val Malenco and Sondrio (Italy), Falotta near Tinizong (formerly Tinzen), and Fianel in Val Ferrera (Switzerland) (Niggli et al., 1940; Weibel, 1996; Brugger, 1996).

A comparison of these mineral occurrences, based on the available literature, is attempted in Table 1, and shows some similarity among the assemblages. This fact might be thought to indicate a similarity between the various manganese deposits. Actually, the similarities are overbalanced by the differences in age, geological history, host rocks and chemistry.

With regard to age, the Val Graveglia deposit and the Western and Central Alps deposits are geologically relatively young. They began to form about 100 million years ago, much more recently than the Franklin and Sterling Hill deposits (about 1000 million years), the Langban deposit (about 1800 million years) and the Kalahari manganese deposit (2200-2300 million years).

Regarding environment, most of the deposits mentioned above were formed in continental or shallow basin environments and are hosted by carbonate rocks. The radiolarite-hosted Apennine deposits of Val Graveglia, however, seem to be related more to oceanic conditions, although the discovery of fossilized land plants could suggest a complex paleogeography or a silica availability not related to deep water but to the chemistry of the environment and to a strong volcanic activity.

Some analogies can be found in Alpine deposits related to radiolarite outcrops such as Parsettens and Falotta or Scerscen which, although smaller, developed in a similar way and have approximately the same age.

The metamorphism at Val Graveglia only reached greenschist facies. The old New Jersey and Swedish deposits reached much higher metamorphic conditions, and the Franklin-Sterling Hill mineral assemblages are proof of sillimanite-facies metamorphism. The South African Kalahari deposit was strongly remobilized by a metamorphic event which happened about 1250 million years ago. Also, the Alpine deposits, such as Praborna and other localities mentioned above, are generally known to have reached higher pressure and/or higher deformation conditions. The Apennine ophiolites are in fact well-preserved in comparison with the Alpine ones.

Chemically the Val Graveglia manganese deposits are silicahosted and have a low iron content. Other elements like lead, zinc and antimony are either absent or present in very small amounts. The only zinc mineral observed there to date is sphalerite, found only rarely. Lead is also considered rare. Pyrobelonite and even the common (elsewhere) species galena were found in just a few specimens. The Franklin and Sterling Hill zinc-iron-manganese deposits are marble-hosted. The Langban and the Fianel deposits are dolomitic carbonate-hosted and quite rich in carbonate minerals. The Kombat mine deposit is hosted in an iron-manganese silicate-carbonate-oxide unit, associated with a copper-lead-silver sulfide orebody, and it would be difficult to find analogies with the Val Graveglia deposit.

An interesting chemical peculiarity of the Val Graveglia district is the presence of vanadium. Vanadium-bearing species are known, for example, at Franklin (goldmanite, pyrobelonite and descloizite) and in the Postmasburg deposit (gamagarite). But at Val Graveglia a number of minerals with essential vanadium in their structure have been found: gamagarite, haradaite, medaite, palenzonaite, Pyrobelonite, reppiaite, saneroite, tangeite, vanadomalayaite and volborthite.

According to recent data (Marescotti, 1993; Baroni, 1998), some elements like vanadium and arsenic do not appear to be particularly widespread in the ore or in the rock mass, but form minerals only in this particular environment. From this point of view the closest analogy seems to be with the Fianel deposit, the type locality for fianelite and the second world occurrence of palenzonaite, saneroite and johninnesite.

It may be noted that the dimensions of these manganese deposits are quite different. The Val Graveglia district consists of a group of medium-small deposits, whose cumulative production ranged between 1,000,000 and 1,200,000 tons. These dimensions are comparable with those of the Swedish deposits, while the New Jersey and the South African deposits are much larger. The Alpine manganese occurrences arc even smaller and became economical only locally and at times when the manganese prices were high.

Some analogies between the various localities mentioned above can be found in the volcanic-sedimentary origin of manganese in concentrations of economic interest. Manganese often originates from volcanic fumarolic activity or from the upwelling of cold deep ocean water; from this point of view the analogy with the Kalahari manganese deposit is impressive. In both cases the volcanic activity is well represented by the presence of pillow lavas at the base of the sequence, underlying the manganese strata.

The general features of the Val Graveglia geological history, with a metamorphic event followed by an uplift, cannot be considered to be similar to those of the other localities, because of the differences in timing and metamorphic grade. In conclusion, the similarities suggested by the mineral check list in Table I are mainly due to the circulation of fluids in fractures, to the abundance of manganese, the availability of arsenic and to the presence of other elements such as copper, calcium, barium, vanadium etc. Consequently the Val Graveglia deposit can be considered essentially unique.

MINERALS

Alabandite [Mn.sup.2+]S

Alabandite has been found at the Molinello mine, in the deepest part of the deposit. Not too common there, it was collected in the second half of the 1980's, commonly as green crusts which rapidly turn black (Palenzona, 1996). The crystals, often forming rounded aggregates up to 6 mm, are rare. It is frequently associated with neotocite, manganoan calcite and, sometimes, rhodonite,

Albite [NaAlSi.sub.3][O.sub.8]

Albite is common as tiny crystals in the chert veins. Some attractive specimens from the Molinello mine show crystals up to 2 cm, associated with quartz, ganophyllite, kutnahorite and, in places, hematite or sulfides.

Allophane

Allophane, an amorphous hydrous aluminum silicate, was found as a secondary mineral at the Gambatesa, Cassagna and Molinello mines. Some very attractive specimens came from the small copper deposit of Reppia, where nice vugs (up to 12 cm) lined with the copper-bearing variety were found.

Anatase [TiO.sub.2]

Red to brown anatase crystals up to 1 mm in length have been found in the dump material at the Gambatesa mine, in association with quartz, clinochlore, apatite and sulfides. Anatase is also widespread in radiolarites at Monte Chiappozzo and several other localities.

Andradite [Ca.sub.3][[Fe.sup.3+].sub.2][([SiO.sub.4]).sub.3]

Very small yellow to green crystals of andraditic garnets have sometimes been collected in the serpentine outcrops, in particular in the Gambatesa mine area.

Aragonite [CaCO.sub.3]

Aragonite is quite rare in Val Graveglia. Some specimens were found in serpentinite outcrops. Elongated crystals collected at the. Gambatesa mine and misidentified as aragonite are actually calcite (Palenzona, 1980).

Arseniosiderite [Ca.sub.2][[Fe.sup.3+].sub.3][([AsO.sub.4]).sub.3][O.sub.2]*3[H.sub.2 ]O

Arseniosiderite has recently been found at the Gambatesa mine in fractures in chert, as yellow to brown rosettes up to 2 mm, associated with clinoclase. It has also been collected at the Cassagna mine in fossil wood, with chrysocolla.

Arsenosulvanite [Cu.sub.3](As, V)[S.sub.4]

The rare species arsenosulvanite has been found as small bronze-colored masses in association with goldmanite, rhodonite and carbonates. The crystals are very rare and extremely small.

Azurite [[Cu.sup.2+].sub.3][([CO.sub.3]).sub.2][(OH).sub.2]

Azurite is one of the minerals formed by the weathering of copper sulfides. Nice specimens, with prismatic crystals up to 1 cm, were collected in silicified woods at the Cassagna mine and at the Scrava mine. In this last case the association is quite interesting, showing cuprite, volborthite and several arsenates.

Bakerite [Ca.sub.4][B.sub.4]([BO.sub.4])[([SiO.sub.4]).sub.3][(OH).sub.3]*[H.s ub.2]O

The boron-bearing mineral bakerite was found only once, to date, as small (1-2 mm) white sprays on well-crystallized rhodonite, at the Gambatesa mine (Borgo and Palenzona, 1998; Palenzona, 1996).

Barite [BaSo.sub.4]

It is often present in the veins of the manganese ore, in crystals occasionally reaching 8 cm in length. The barite specimens are quite aesthetic because of their complex habit, luster and association with rare species. Commonly found during only a few periods of mining activity, barite has been collected in all of the manganese mines. Remarkable crystals associated with rhodochrosite came from the Gambatesa and Cassagna mines, and good specimens on rhodonite were collected at the Molinello mine in the 1980's. The larger crystals normally have a simple, tabular habit, while the small ones are often rich in forms.

Bastnaesite-(Ce) (Ce,La)([CO.sub.3])F

Bastnaesite-(Ce) has been found in intimate intergrowth with small (less than 1 mm), rare synchysite-(Ce) crystals at Pontori prospect, in veinlets cutting the chert. These crystals are associated with quartz, anatase and clinochlore (Borgo and Palenzona, 1988).

Bementite [[Mn.sup.2+].sub.8][Si.sub.6][O.sub.15][(OH).sub.10]

Bementite has been found in cream-white to violet rosettes up to 2 cm, in association with calcite and hausmannite at the Molinello and Gambatesa mines. Its presence in other Val Graveglia localities is doubtful.

Bornite [Cu.sub.5][FeS.sub.4]

Bornite has been found occasionally at the Gambatesa and Molinello mines in small specimens rarely showing crude crystals (Marescotti, 1993).

Braunite [Mn.sup.2+][[Mn.sup.3+].sub.6][SiO.sub.12]

Braunite forms the main part of the manganese ore in all the Val Graveglia mines, as layers within chert and as large masses up to 20 meters in thickness. In spite of the abundance of massive ore, the crystals are small (1-2 mm) and not very common. They are associated with calcite, ganophyllite and barite. At the Cassagna mine good microcrystals of braunite associated with conichalcite crystals have been collected.

Brochantite [[Cu.sup.2+].sub.4]([SO.sub.4])[(OH).sub.6]

Brochantite has been found as a secondary mineral on copper minerals, both in the copper and in the manganese deposits. Good specimens were found in the fractures of the silicified woods at the Scrava and Cassagna mines.

Calcite [CaCO.sub.3]

Calcite is extremely common in cavities in basalt, in fractures in serpentinite, in fractures and cavities in the Calpionella limestone, and in veins in radiolarite. The best specimens, colorless scalenohedra up to 5 cm, were collected in the 1960's at the Gambatesa mine. Calcite is usually the last vein mineral to have been deposited and commonly fills the vugs. By treatment with diluted acid it is sometimes possible to obtain good specimens of rhodonite and tinzenite with quartz. The acid treatment must be done with caution, as it can destroy or damage carbonates (kutnahorite and rhodochrosite), several silicates (especially phyllosilicates, such as ganophyllite), native copper and some of the rare vanadium minerals, such as palenzonaite and gamagarite.

Calcite forms a series with rhodochrosite and many specimens from the manganese deposit are of the manganoan variety. They often show a pale pink color in natural light and fluoresce bright pink in both longwave and shortwave ultraviolet light.

Carpholite [Mn.sup.2+][Al.sub.2][Si.sub.2][O.sub.6][(OH).sub.4]

Carpholite is found as aggregates of yellow fibers in the quartz veins which cut chert. It was one of the first minerals to crystallize, sometimes followed by sursassite, tinzenite and carbonates. Carpholite is commonly enclosed in quartz, and the free crystals, which can reach I cm, are very rare, whereas the fibers can be up to 3 cm long. It has been found only a few times at the Gambatesa mine and at the Molinello mine (Antofilli et al., 1983; Palenzona, 1991).

Caryopilite [([Mn.sup.2+],Mg).sub.3][Si.sub.2][O.sub.5][(OH).sub.4]

Caryopilite is not common, although it was collected in some abundance during a few limited periods, mainly at the Gambatesa mine, in association with rodonite and, sometimes, barite. Caryopilite forms small spheres (1-2 mm) and aggregates of brown to pale brown plates. In places it covers or replaces carbonates to form perimorphs or pseudomorphs.

Chalcocite [Cu.sub.2]S

Chalcocite is widespread in the quartz veins at the Gambatesa, Molinello and Scrava mines, commonly as massive material but also in beautiful, well-formed crystals, usually a few millimeters across rarely reaching 4 cm. It is associated with quartz, calcite, copper, ganophyllite and other sulfides. Chalcocite associated with native gold was found in the early 1980's at the Gambatesa mine (Pipino, 1983).

Chalcophanite (?) (Zn,[Fe.sup.2+],[Mn.sup.2+])[[Mn.sup.4+].sub.3][O.sub.7]*3[H.sub.2]O

The presence of chalcophanite at Val Graveglia, reported as doubtful by Borgo and Palenzona (1988), has not been confirmed by analytical data.

Chalcophyllite [[Cu.sup.2+].sub.18][Al.sub.2][([AsO.sub.4]).sub.3][([SO.sub.4]).sub. 3][(OH).sub.27]*33[H.sub.2]O

Chalcophyllite has been found in good crystals, rarely over 1 cm in diameter, in fractures in fossil wood at the Cassagna mine and especially at the Scrava mine, where the best specimens were found in association with other secondary As and Cu minerals. It has also been found at the Gambatesa mine, as a secondary mineral in tennantite and quartz veins.

Chalcopyrite [CuFeS.sub.2]

Chalcopyrite, widespread in small masses, was found at the Gambatesa mine as crystals up to 5 mm in a quartz vein. Masses up to a few cubic meters were mined from the small sulfide deposits associated with the basalts. In the outcrops it is usually deeply weathered, forming secondary minerals such as malachite and allophane.

Chernovite-(Y) [YasO.sub.4]

Chernovite-(Y), first described from Russia and later found at Mount Cervandone on the boundary between Italy and Switzerland, is very rare. It was found just once at the Molinello mine, as pink prismatic crystals up to 2 mm in a hematite vein associated with calcite (Borgo and Palenzona, 1988; Palenzona, 1988). The analysis is in good agreement with the available data, 80% of the REE being Y A specimen from the same locality shows unidentified, very small, greenish yellow prismatic crystals; a microprobe analysis indicates Nd in substitution for Y, suggesting the possibility of a new species. So far further studies have not been possible because of the lack of material (Balestra, personal communication).

Chrysocolla [([Cu.sup.2+],Al).sub.2][H.sub.2][Si.sub.2][O.sub.5][(OH).sub.4][nH.s ub.2]O

Amorphous phases mainly consisting of chrysocolla are common in the copper deposits of Val Graveglia and are widespread as an alteration product of the copper minerals.

Clinochlore [(Mg,[Fe.sup.2+]).sub.5]Al([Si.sub.3]Al)[O.sub.10][(OH).sub.8]

Clinochlore is rather common, especially in the fractures of chert, in association with quartz, calcite, anatase, orthoclase etc.

Clinochrysotile [Mg.sub.3][Si.sub.2][O.sub.5][(OH).sub.4]

Chlinochrysotile is known only as a rock-forming mineral in serpentines.

Clinoclase [[Cu.sup.2+].sub.3]([AsO.sub.4])[(OH).sub.3]

Clinoclase has been found as blue crystals up to 3 mm at the Gambatesa mine in association with arseniosiderite in chert fractures. Other finds, such as the ones reported in the fossil woods from the Scrava mine, have not been confirmed by analytical data.

Conichalcite [CaCu.sup.2+]([AsO.sub.4])(OH)

Collected since the early 1970's, concichalcite has been found sporadically, mainly at the Cassagna mine and at the Gambatesa mine (both finds are confirmed by analytical data; Antofilli et al., 1983). The better specimens are undoubtedly those from the Cassagna mine, with pale green prismatic crystals up to 2 mm, sometimes associated with braunite, calcite, piemontite and barite crystals. Another commonly associated mineral is botryoidal pyrolusite. Conichalcite was found quite widespread in the early 1980's, but at present well-crystallized specimens are considered uncommon.

Connellite [[Cu.sup.2+].sub.19][Cl.sub.4]([SO.sub.4])[(OH).sub.32]*3[H.sub.2]O

Good crystals of connellite up to 2 mm were found in the cavities in silicified wood. It is also present in quartz veins, always associated with cuprite and other copper minerals. The best specimens are from the Cassagna mine, but it has also been found at the Gambatesa mine, the Molinello mine and near Reppia.

Copper Cu

Native copper was found in the gossan of the copper and iron deposits, but the finest specimens were collected in the manganese mines. Spectacular specimens were found during the late 1960's at the Gambatesa mine in a manganoan calcite vein, in association with chalcocite and ganophyllite. In the 1990's a few spectacular specimens in aggregates over 30 cm long were collected again at the Gambatesa mine. Remarkable specimens associated with rhodonite were found at the Molinello mine, especially in 1986; in this case the copper filled rock fractures, forming laminae of several square centimeters up to 1 cm thick and dendritic aggregates with crystals up to 1 cm or more showing dodecahedron, octahedron and cube forms. Those attractive specimens show a rich association, with good crystals of rhodonite, barite, pyrobelonite, chalcocite, quartz, calcite and montmorillonite.

Cornubite [[Cu.sup.2+].sub.5][([AsO.sub.4]).sub.2][(OH).sub.4]

Cornubite has been found at the Cassagna and Scrava mines, as millimetric green spheres in the fractures in fossil wood. It is considered rare in the area. In places it is associated with cornwallite (Balestra, 1992; 1993).

Cornwallite [[Cu.sup.2+].sub.5][([AsO.sub.4]).sub.2][(OH).sub.4]

Cornwallite has been collected a few times at the Cassagna mine as crusts and millimetric spheres in the fractures in fossil wood. It is in places associated with cornubite and other arsenates.

Covellite CuS

Tiny lamellae of covellite on chalcocite have been reported from the Gambatesa mine (Antofilli et al., 1983).

Crednerite [CuMnO.sub.2]

Crednerite is a rare mineral, found for the first time in 1847 at Friedrichroda (Germany) and later in just a few more localities, always in small amounts. Tabular, black and very lustrous crystals were found at the Gambatesa mine in the fractures in braunite and at the Molinello mine in vugs in rhodonite veins (Palenzona, 1987), at the same time that tangeite was collected. It is considered very rare, but accurate analysis of the black minerals occurring in these localities might reveal more specimens.

Cuprite [[Cu.sup.1+].sub.2]O

Small, nice cubic or octahedral cuprite crystals up to 2 mm were collected both in the copper and in the manganese mines. Probably the most interesting specimens are those found in silicified wood, associated with volborthite, several arsenates and, in places, connellite and spangolite. The acicular variety is also widespread, particularly at the Gambatesa mine.

Datolite (?) [Ca.sub.2][B.sub.2][Si.sub.2][O.sub.8][(OH).sub.2]

The presence of the boron-bearing mineral datolite, reported from Gambatesa by some collectors, has not been confirmed.

Devilline [[CaCu.sup.2+].sub.4][([SO.sub.4]).sub.2][(OH).sub.6]*3[H.sub.2]O

Devilline has been found in radiolarite veinlets with other secondary copper minerals (Palenzona, 1996).

Digenite [Cu.sub.9][S.sub.5]

Specimens with small digenite masses are known from the Gambatesa and the Monte Bardeneto-Monte Capra mines (Antofilli et al., 1983).

Diopside [CaMgSi.sub.2][O.sub.6]

Interesting specimens showing brown crystals of a calcium and magnesium pyroxene (manganese and iron-bearing) in association with ganophyllite and calcite came to light in the middle 1980's at the Molinello mine, and were reported as manganoan diopside (Borgo and Palenzona, 1988). Diopside is also common as a rockforming component in the gabbros of the ophiolitic basement.

Djurleite [Cu.sub.31][S.sub.16]

Djurleite, an example of non-stoichiometric copper sulfide, has been identified just once as small black crystals from the Molinello mine, associated with rhodonite, barite and ganaphyllite (Borgo and Palenzona, 1988).

Dolomite CaMg[([Co.sub.3]).sub.2]

Dolomite is found with other carbonates in the veins cutting the main mineralized zone, as rounded rhombohedra and in typical saddle-shape aggregates. The crystals are up to 8 mm in size and range from white to pale pink. It was collected in almost all the manganese mines.

Epidote [Ca.sub.2][([Fe.sup.3+],Al).sub.3][([SiO.sub.4]).sub.3](OH)

Epidote has been found as bright crystals up to 1 cm in cavities in the basalts, at Nascio, at Pontelagoscuro near the Molinello mine, at the Gambatesa mine and at several other localities. When associated with quartz, calcite, orthoclase (var. adularia), pumpellyite and prehnite it forms attractive specimens.

Fluorapatite [Ca.sub.5][([PO.sub.4]).sub.3]F

Tabular white crystals of fluorapatite up to 1 cm were found on rhodonite at the Gambatesa mine (Palenzona, 1984). Small "apatite" crystals were also observed in chert fractures with quartz, clinochlore and anatase.

Fluorapophyllite [KCa.sub.4][Si.sub.8][O.sub.20](F,OH)*8[H.sub.2]O

Just a few specimens of fluorapophyllite, in crystals up to 3 mm, have been found with yellow rhodonite crystals in a block of ore at the Molinello mine.

Galena PbS

Galena has been found as small cubic crystals with chalcopyrite in a quartz vein at the Gambatesa mine, and also in the local limestone quarries. Lead is an uncommon element in Val Graveglia and consequently galena is rare.

Gamagarite [Ba.sub.2]([Fe.sup.3+],[Mn.sup.3+])[([VO.sub.4]).sub.2](OH)

One of the most interesting minerals from this area is gamagarite, this being the second occurrence, after the original find in the Postmasburg, South Africa, manganese field, where it forms brown-red veins. It was observed several times at the Molinello mine (Basso and Palenzona, 1988) and, as a rarity, at the Gambatesa mine. The specimens from the Molinello mine, with crystals up to 1 cm, in rhodonite cavities or in the quartz veins that cut the braunite ore, are the best in the world. A possible third occurrence of gamagarite is under study based on material from the Cerchiara mine, about 25 km southeast of Val Graveglia (Balestra and Bracco, personal communication).

Ganophyllite [(K,Na).sub.2][(Mn,Al,Mg).sub.8][(Si,Al).sub.12][O.sub.29][(OH).sub.7 ]*8-9[H.sub.2]O

Ganophyllite is a rare species occurring in beautiful specimens at Val Graveglia. The most spectacular ones, from the Molinello mine, show platy, micaceous crystals up to 5 mm forming large druses in the quartz veins crossing chert. Ganophyllite usually lies on hematite and quartz, and is often associated with rhodochrosite or manganoan calcite. The Gambatesa mine also produced good specimens, with single crystals up to 1 cm, and in aggregates lining chert fractures. The color ranges from cream to yellow to brown, and the most common association is with barite, quartz, rhodochrosite and other carbonates. Spherules and platy aggregates of lamellae were also found in relative abundance in some periods in all the manganese mines of the district.

Some of the Molinello and Gambatesa specimens are probably among the best in the world for this species. According to the literature (Cortesogno et al., 1979; Antofilli et al., 1983) the micaceous specimens once labeled as parsettensite are to be considered ganophyllite. However, a later work (Eggleton et al., 1994) indicates that at least some specimens from Gambatesa are indeed parsettensite.

A calcium-rich variety with Ca[greater than]Na[much greater than]K ("calcio-ganophyllite") is reported from the Molinello mine (Mottana and Della Ventura, 1990).

Goethite [alpha]-[Fe.sup.3+]O(OH)

Goethite is very common, especially in the gossan of the pyrite deposits, as black, red or yellow masses of "limonite."

Gold Au

Gold is extremely rare in the Val Graveglia district. It was found at the Gambatesa mine in the early 1980's as small dendrites associated with chalcocite in a quartz vein (Pipino, 1983). Another find took place in the 1990's, in aggregates up to 5 mm, with chalcocite, tennantite and quartz.

Goldmanite [Ca.sub.3][(V,Al,[Fe.sup.3+]).sub.2][([SiO.sub.4)].sub.3]

Another very interesting mineral at Val Graveglia is goldmanite, a vanadium-bearing garnet found in places in 1988, 1992 and 1996 at the Gambatesa mine, as small (about 1 mm) but perfect green to brown-green dodecahedral crystals associated with manganaxinite, albite, calcite, pennantite, and a vanadium-rich pumpellyite (Palenzona, 1991).

Gravegliaite [Mn.sup.2+]([SO.sub.3])*3[H.sub.2]O

The hydrated manganese sulfite mineral gravegliaite is the third known example of a natural sulfite, after the lead-bearing scotlandite and calcium-bearing hannebachite. It was described as a new species from specimens collected at the Gambatesa mine, where it was found as small (up to 0.5 mm), prismatic, colorless orthorhombic crystals which turn brown-black. The crystals sometimes form sheaf-like or radial aggregates. It occurred very sparingly at the surface of cavities and fractures in a manganese ore containing tephroite, bementite, braunite, hausmannite and hematite. The presence of this phase does not appear to be related to the chemistry of the matrix, which lacks sulfur-bearing minerals. The authors of the article describing it as a new species (Basso et al., 1991) suggested a possible origin involving sulfur from the underlying ophiolitic breccias or from the overlying pelitic layers and suggested precipitation from [S.sup.2-] bearing brines. Gravegliaite is named after the Val Graveglia district.

Gypsum [CaSO.sub.4]*2[H.sub.2]O

Gypsum is common in some old workings as an alteration product of the pyrite masses. Colorless crystals were also found in the basalt cavities at the Molana quarry.

Haradaite [[Sr.sub.2][[V.sup.4+].sub.2]).sub.2]([Si.sub.4][O.sub.12])

The rare strontium-bearing and vanadium-bearing mineral haradaite, previously reported only from the type locality, the Noda-Tamagawa mine (Iwate, Japan), and from the Yamato mine (Kagoshima, Japan) is one of the most interesting minerals found in the district. It occurred at the Gambatesa mine as attractive small crystals up to 5 mm having a beautiful emerald-green color, in thin veinlets in the red chert, in association with quartz, calcite and the new species vanadomalayaite. Haradaite was collected in just a few specimens; the crystals are elongated parallel to [100] and show good {010} cleavage. The Gambatesa haradaite is of nearly pure end-member composition, with the molar fraction of the Ba analog suzukiite not exceeding 14%. This allowed the accurate refinement of the crystal structure of the mineral (Basso et al., 1995).

Harmotome [([Ba.sub.0.5],[Ca.sub.0.5],K,Na).sub.5] [[Al.sub.5][Si.sub.11][O.sub.32]]*12[H.sub.2]O

Zeolite crystals visually identifiable as phillipsite or harmotome are well-known as last-formed minerals in carbonate veins, braunite fractures and tinzenite druses (Antofilli et al., 1983). Recently microprobe analyses (Balestra, personal communication) have shown that the barium content in these specimens is very high and they should be classified as harmotome. It occurs, associated with carbonates, barite and manganese oxides, at the Gambatesa, Molinello and Cassagna mines.

Hausmannite [Mn.sup.2+][[Mn.sup.3+].sub.2][O.sub.4]

Hausmannite is a common species, especially at the Gambatesa mine. It is rarely found in crystals and can easily be misidentified as braunite. A close examination of the color can be a clue: usually hausmannite is dark brown while braunite is black. Nevertheless only an accurate analysis can verify the identification.

Hematite [alpha]-[Fe.sub.2][O.sub.3]

Hematite is very common, but does not occur in attractive specimens. It was one of the first minerals to crystallize in the chert veins, as lamellae up to 3 mm, sometimes grouped in rosettes. It is frequently followed, and usually covered, by quartz, calcite and ganophyllite.

"Hornblende"

Found as a rock-forming mineral, "hornblende" occurs in small crystals in the diorites of the ophiolitic complex. Some specimens are reported from the Gambatesa mine (Antofilli et al., 1983).

Ilmenite [Fe.sup.2+][TiO.sub.3]

Ilmenite has been observed in thin section and as small (1-2 mm) concentrations in basic rocks from the Cassagna and Scrava mines (Antofilli et al., 1983).

Inesite [Ca.sub.2][[Mn.sup.2+].sub.7][Si.sub.10][O.sub.28][(OH).sub.2]*5[H.su b.2]O

Inesite has been found just a few times at the Gambatesa mine as pink veinlets in the main orebody, and rarely as crystals up to a few millimeters. Inesite is difficult to identify in the field because of its similarity to the more common fibrous rhodonite and pyroxmangite.

Johannsenite [CaMn.sup.2+][Si.sub.2][O.sub.6]

An uncommon clinopyroxene in the area, johannsenite was occasionally collected at the Molinello mine in veins in the manganese ore, as pale apple-green masses up to several centimeters, and sometimes as well-formed crystals. It is usually associated with calcite.

Kutnahorite Ca([Mn.sup.2+],Mg,[Fe.sup.2+])[([CO.sub.3]).sub.2]

Kutnahorite is a Mn-rich carbonate belonging to the dolomite group. Specimens from Val Graveglia similar to this species have been studied at the University of Genoa (Cortesogno et al., 1979). Their composition showed more calcium than in the theoretical formula, but on the basis of X-ray data they cannot be considered a manganoan calcite. This material, which shows analogies with the Ca-rich kutnahorite found at Langban, Sweden, is not especially rare among the last minerals formed in the veins of the manganese ore. The best specimens are pink to cream-colored elongated aggregates up to 6 cm long that sometimes resemble the shape of a club. It can be associated with barite, tinzenite, caryopilite, zeolites and many other species. Specimens recently collected at the Cassagna mine before the end of the operations show pink clubs up to 2 cm, and are very similar to the kutnahorite from the South African fields (Cairncross, et al., 1997).

Langite [[Cu.sup.2+].sub.4]([SO.sub.4])[(OH).sub.6]*2[H.sub.2]O

Langite has been found as crystals up to 3 mm in the gossan at the old Bardeneto-Monte Capra excavations, in the manganese mines as an alteration of the copper sulfides, and in fractures in fossil wood. Good specimens of langite were collected at the Scrava mine.

Lavendulan [[NaCaCu.sup.2+].sub.5][([AsO.sub.4]).sub.4]Cl*5[H.sub.2]O

Lavendulan has been found as spherules up to 2 mm in quartz cavities, in association with chalcocite, tennantite and calcite, only at the Gambatesa mine.

Magnetite [Fe.sup.2+][[Fe.sup.3+].sub.2][O.sub.4]

Magnetite has been found in serpentinized peridotites and in basalts as small masses and as rare, small (less than 1 mm) subeuhedral crystals.

Malachite [[Cu.sup.2+].sub.2]([CO.sub.3])[(OH).sub.2]

Malachite is very common, in both the copper and manganese mines of Val Graveglia. The most attractive specimens are druses up to 20 by 15 cm with spherules up to 8 mm, which were found in a weathered zone of the small copper deposit at Reppia. It is also common in fossil wood at Gambatesa and at the Scrava mine, and is associated with copper sulfides in many other localities.

Manganaxinite [Ca.sub.2][Mn.sup.2+][A1.sub.2][Bsi.sub.4][O.sub.15](OH)

Manganaxinite was found at the Gambatesa mine in chert veins as good crystals, gray-greenish to violet in color and up to 5 mm in length. Specimens collected in the 1980's show only a few associated species, while the ones found in 1992 are part of a very interesting assemblage with manganaxinite partially covered by albite, goldmanite, ganophyllite, vanadium-rich pumpellyite and calcite.

In the past, some dark-colored specimens of tinzenite were misidentified as manganaxinite (or as ferroaxinite, the presence of which has not been confirmed).

Manganberzeliite [(Ca,Na).sub.3][([Mn.sup.2+],Mg).sub.2][([AsO.sub.4]).sub.3]

Manganberzeliite has been found only once, on a chert fracture at the Cassagna mine, as very small, yellow aggregates (Palenzona, 1996). Microprobe analysis showed no Mg in this material.

Manganite [Mn.sup.3+]O(OH)

Though perhaps not very rare, only a few specimens of manganite have been identified by analysis. At the Cassagna mine specimens with crystals up to 1 cm were collected, while the Molinello mine produced sprays of lustrous crystals in quartz vein (Antofilli et al., 1983; Borgo and Palenzona, 1988).

Marcasite [FeS.sub.2]

Good marcasite specimens are not very common in Val Graveglia. The best, with sharp, lustrous crystals up to 3 mm, were collected at the beginning of the 1990's in braunite veins, associated with carbonates, barite and, in places, phillipsite.

Marsturite [Na.sub.2][[CaMn.sup.2+].sub.3][Si.sub.5][O.sub.14](OH)

The rare silicate marsturite, a member of the nambulite group, was originally described from Franklin, New Jersey (Peacor et al., 1978; Dunn and Leavens, 1986), and was also recognized in orange to yellow crystals up to 2 mm from the Molinello mine, associated with braunite, barite and calcite (Palenzona, 1987b). In that period the mine produced large amounts of ore very rich in veins, often containing pink to yellow rhodonite. Examination of those veins led to the discovery of good specimens of marsturite and pyroxmangite. Marsturite is quite rare, and often the so-called "marsturite" specimens turn out to be just rhodonite.

Medaite [([Mn.sup.2+],Ca).sub.6]([V.sup.5+],[As.sup.5+])[Si.sub.5][O.sub.18]( OH)

Medaite is a very rare species for which the Molinello mine is the type locality; it has also been reported from Fianel in Val Ferrera, Switzerland. Medaite has a good (100) cleavage, in places occurring as oriented lamellae in tiragalloite or on pyroxmangite crystals, suggesting a syntaxial growth. A characteristic feature of its crystal structure is the presence of a vanadatopentasilicate ion.

This mineral was originally studied in braunite ore collected at the Molinello mine, consisting of veinlets in the braunite ore in which medaite was associated with quartz, calcite, ganophyllite and another new species, tiragalloite. It was named in honor of the Italian mineral collector Francesco Meda (1926-1977) (Gramaccioli et al., 1979; Gramaccioli et al., 1982).

The specimens show brownish red granules up to 1.5 mm. No more were found for several years after the first occurrence. More specimens later collected at the Cassagna mine have a very similar association (Borgo and Palenzona, 1988). In 1988 good prismatic, bright red crystals were found, again at Molinello mine, on braunite in a quartz vein. Other sporadic finds followed until May 1996 when, just a few days before the closing of the Molinello mine, the best specimens of medaite to date were found, with well-formed red to orange crystals up to 2 mm in druses of several square centimeters.

The three minerals, medaite (monoclinic), saneroite (triclinic) and tiragalloite (monoclinic), for which Val Graveglia is the type locality, are not easy to recognize without analytical data, especially if the specimens do not show crystals. The color, usually orange to yellow for tiragalloite, orange to brown for saneroite and orange to brownish red for medaite, may be a clue, but cannot be used to identify those minerals with certainty. The least rare of the three species is saneroite, while the other two are quite scarce.

Montmorillonite [(Na,Ca).sub.0.3][(Al,Mg).sub.2][Si.sub.4][O.sub.10][(OH).sub.2] [nH.sub.2]O.

Montmorillonite occurs in veins in the manganese ore. Nice specimens, with crystals forming rosettes up to 3 mm, were found in association with native copper at the Molinello mine in the middle 1980's (Borgo and Palenzona, 1988).

Nabiasite [BaMn.sub.9][[(V,As)[O.sub.4]].sub.6][(OH).sub.2]

Nabiasite is a recently described mineral, found in the Pyrenees in just one specimen (Brugger et al., 1999). Some specimens collected in 2000 at the Gambatesa mine were identified as the second world occurrence of nabiasite (Brugger, pers. comm.), and the first occurrence in euhedral cubic crystals. This mineral occurred with quartz in veinlets crossing a braunite-hausmannite ore. It must be considered extremely rare, and difficult to recognize without an analysis, because its red color and general appearance are very similar to those of palenzonaite, gamagarite, pyrobelonite and "yamatoite."

Neotocite ([Mn.sup.2+],[Fe.sup.2+])[SiO.sub.3]*[H.sub.2]O (?)

The brown to black manganese silicate neotocite has a low degree of crystallinity and is not well defined. It was found several times at the Gambatesa mine, as small masses associated with quartz, braunite, calcite and rhodonite. Neotocite often fills little vugs, and sometimes forms transparent brown botryoidal crusts. This mineral was also common at the Molinello mine, with similar associations. Here neotocite pseudomorphs after alabandite crystals, associated with barite, were also found.

Nimite (?) [(Ni,Mg,[Fe.sup.2+]).sub.5](Al([Si.sub.3])[O.sub.10][(OH).sub.8]

Some brown lamellae were found at the Molinello mine in quartz veins, associated with sursassite and ganophyllite. Similar specimens were also collected at Gambatesa mine. The analysis (Palenzona, 1996) yielded a tentative identification as manganoan nimite.

Olivenite [[Cu.sup.2+].sub.2]([AsO.sub.4])(OH)

Olivenite was found in the 1990's in the dumps of the Gambatesa mine, in quartz veins with arseniosiderite and in some tinzenite veins, associated with chalcocite and quartz. Other specimens were collected in fossil wood from the Cassagna and Scrava mines. Olivenite forms green crystals and sprays up to 5 mm.

Opal [SiO.sub.2]*[nH.sub.2]O

Veinlets in the manganese ore showing the typical opalescence have been found at the Molinello and Gambatesa mines (Borgo and Palenzona, 1988).

Orpiment [As.sub.2][S.sub.3]

Orpiment has been reported as small masses from the Molinello mine (Palenzona, 1996). It is very rare in Val Graveglia.

Orthoclase [KalSi.sub.3][O.sub.8]

The transparent variety of orthoclase was collected several times as crystals up to 1 cm in veins cutting chert, in association with quartz and ganophyllite. It is also commonly associated with epidote in several basalt outcrops, as at Nascio, where the crystals reach 3 cm in length.

Palenzonaite ([Ca.sub.2]Na)[[Mn.sup.2+].sub.2][([VO.sub.4]).sub.3]

Palenzonaite, a very rare mineral, is cubic with a garnet-type structure in which V (and a small amount of As) replaces Si. It is one of the most interesting minerals at Val Graveglia, described for the first time from material collected at the Molinello mine, and named in honor of Andrea Palenzona (1935- ), Professor of Chemistry at the University of Genova (Palenzona, 1986a; Basso, 1987).

This vanadate was found for the first time in the 1980's in a calcite-filled and quartz-filled fracture crosscutting the manganese ore, as wine-red crystals up to 6 mm showing dodecahedral and trapezohedral forms. In 1993 some specimens with cubic crystals up to 7 mm were found, again in a calcite vein in the main ore mass. The occurrence of crystals is rare; most of the palenzonaite specimens are compact masses or veinlets up to 1 cm thick.

The Molinello mine remained the only known locality for palenzonaite for several years, until the discovery of the Val Ferrera, Switzerland, occurrence; nevertheless the Val Graveglia specimens are by far the best.

Parnauite [[Cu.sup.2+].sub.9][([AsO.sub.4]).sub.2]([SO.sub.4])[(OH).sub.10]*7[H .sub.2]O

Parnauite is not common; it was found as nice tabular crystals up to 3 mm in the cavities of fossil wood at the Scrava mine. The associations include quartz, cuprite, azurite, chalcophyllite, volborthite and other secondary As and Cu minerals.

Parsettensite (K,Na,Ca)[(Mn,Al).sub.7][Si.sub.8][O.sub.20][(OH).sub.8]*2[H.sub.2]O

Parsettensite occurs in platy, micaceous, yellowish to brown crystals on quartz and calcite. It has been verified on some specimens from Gambatesa (Eggleton et al., 1994), and it is probably present at various localities in Val Graveglia. However, it is not easily distinguished, and further study is required.

Pennantite [[Mn.sup.2+].sub.5]Al([Si.sub.3]Al)[O.sub.10][(OH).sub.8]

A vanadium-bearing variety of pennantite, the so-called "grovesite" described in 1955 from the Benallt mine in Wales, has been found at the Gambatesa mine in association with manganaxinite, goldmanite, albite and calcite (Palenzona, 1991).

Pharmacosiderite [[KFe.sup.3+].sub.4][([AsO.sub.4]).sub.3][(OH).sub.4]*6-7[H.sub.2]O

Pharmacosiderite occurs rarely as small yellow crystals at the Gambatesa mine, found in association with olivenite, and in fossil wood at the Cassagna mine, in association with copper and arsenic minerals (Palenzona, 1991).

Piemontite [Ca.sub.2][(Al,[Mn.sup.3+],[Fe.sup.3+]).sub.3][([SiO.sub.4]).sub.3](O H)

Piemontite, a manganiferous member of the epidote group, is common as tiny prismatic crystals and crystal sprays in small amounts in the quartz veins, sometimes in association with barite and tinzenite. Well-formed crystals up to 3 mm on chert were recently collected at the Cassagna mine in association with pyrolusite, quartz and an unidentified yellow silicate in small elongated crystals. Piemontite takes its name after the Italian region of Piedmont.

Posnjakite [[Cu.sup.2+].sub.4]([SO.sub.4])[(OH).sub.6]*[H.sub.2]O

A few millimetric posnjakite crystals were found at the Gambatesa mine in a quartz and tinzenite vein, associated with chalcocite and olivenite.

Prehnite [Ca.sub.2][Al.sub.2][Si.sub.3][O.sub.10][(OH).sub.2]

Prehnite is common in the basalt at Val Graveglia. Crystals up to 1cm and globular white to greenish aggregates up to 3cm were collected at the Molana quarry, in association with epidote, calcite and pumpellyite-(Mg). This association, recognized throughout the Val Graveglia area, attests to metamorphic conditions of low temperature and low pressure (greenschist facies).

Pumpellyite-(Mg) [Ca.sub.2][MgAl.sub.2]([SiO.sub.4])([Si.sub.2][O.sub.7])[(OH).sub.2]* [H.sub.2]O

Pumpellyite-(Mg) is common as a rock-forming mineral in basalt. Sprays up to 1 cm were observed in cavities in the pillow-lavas, especially near the Molana quarry. A mineral similar to pumpellyite-(Mg) but with a high vanadium content has been collected at the Gambatesa mine, in association with goldmanite, ganophyllite and, in places, manganaxinite and albite. The best crystals from this find are included in calcite and can reach a length of 6 mm.

Pumpellyite-([Mn.sup.2+]) [Ca.sub.2]([Mn.sup.2+],Mg)[(Al,[Mn.sup.3+],Fe).sub.2]([SiO.sub.4])-([ Si.sub.2][O.sub.7])[(OH).sub.2]*[H.sub.2]O

Pumpellyite-([Mn.sup.2+]) has been found in a few specimens at the Gambatesa mine, as thin, yellow to brownish, elongated crystals up to 2 mm, in vugs in a quartz vein. It is probably not very rare, but is difficult to recognize when poorly crystallized.

Pyrite [FeS.sub.2]

Pyrite masses, sometimes with fairly high copper content, are widespread in the basalt masses in eastern Liguria, and were mined for a long time. In Val Graveglia there are a few small pyrite workings and prospects, mostly near the village of Reppia and in the Monte Capra and Monte Bianco areas. Crystals are not rare in various rock formations (basalts, shales and chert), and usually show a cubic habit. The largest crystals, 4 cm, were collected at the Gambatesa mine. No particularly attractive pyrite specimens are known from these localities.

Pyrobelonite [PbMn.sup.2+]([VO.sub.4])(OH)

Pyrobelonite is an orthorhombic lead and manganese vanadate, the analog of descloizite in which manganese substitutes for zinc, originally described from Langban, Sweden. It has been found very rarely at the Molinello mine in rhodonite veins, associated with quartz, calcite, braunite and, sometimes, tangeite. It normally occurs in small masses, but sometimes some small (1-3 mm) crystals are found (Borgo and Palenzona, 1988; Palenzona, 1991).

Recently (1998-1999) some specimens were also collected at the Gambatesa mine, as crystals up to a few millimeters and as vein fillings up to several centimeters, associated with bementite, calcite and braunite. This species is not easy to recognize visually, as the non-crystallized specimens are similar to both palenzonaite (cubic) and gamagarite (orthorhombic). Detailed analysis of dark-colored vanadates could lead to the discovery of more specimens of this mineral.

Pyrolusite [Mn.sup.4+][O.sub.2]

Most of the manganese crusts and dendrites found in the area are probably pyrolusite. The dendrites are quite common at all the manganese localities, and can be several centimeters wide. In the quarries of the middle part of the valley it is possible to find dendritic manganese oxides on white limestone. Crystals of pyrolusite are rare; the best specimens, with lustrous, well-formed crystals up to 7 mm, were collected at the Scrava mine in 1994 (Palenzona, 1996). Some weathered crystals up to 1 cm were found at the Cassagna mine.

Pyrophanite [Mn.sup.2+][TiO.sub.3]

Pyrophanite is not very common. Specimens with tiny, tabular, dark red crystals were collected at the Gambatesa mine (Palenzona, 1996).

Pyroxmangite [Mn.sup.2+][SiO.sub.3]

Observed in thin sections (mainly from the Gambatesa mine; Antofilli et al., 1983), pyroxmangite was collected during the last few years of activity of the Molinello mine in nice specimens. It forms orange to creamy yellow elongated crystals up to 1 cm, sometimes associated with calcite, barite and quartz (Borgo and Palenzona, 1988). Other interesting specimens show epitaxial overgrowth of medaite. Nice specimens were also found at the Gambatesa mine, but not as beautiful as the ones from the Molinello mine.

Pyrrhotite [Fe.sub.1-x]S (x = 0-0.17)

Pyrrhotite has been reported as a rare occurrence at the Gambatesa mine (Palenzona, 1991).

Quartz [SiO.sub.2]

Quartz is very common at almost all of the Val Graveglia localities. The crystals can reach several centimeters in length, but only some particular finds are remarkable. Some crystals not showing the prism form are usually associated with rhodonite or ganophyllite from the Molinello mine. The Gambatesa mine produced some specimens of pale amethyst quartz associated with tephroite and hausmannite. Notable quartz specimens from the Gambatesa and Molinello mines show inclusions of sursassite, copper and piemontite (Antofilli et al., 1983). Nice specimens with crystals to 8 cm were also found in the basalt cavities, associated with epidote and orthoclase, at Nascio and at the Molana quarry.

Rancieite (Ca,[Mn.sup.2+])[Mn.sub.4][[blank].sup.4+][O.sub.9]?3[H.sub.2]O

Rancieite, a hydrated Mn oxide containing Ca, has been found at the Gambatesa mine (Antofilli et al., 1983), and probably is not rare in the other Val Graveglia mines. It forms aggregates of spherules and crusts in fractures in the ore. The color is golden brown in the fresh specimens, and black after weathering; it is often associated with quartz (Antofilli et al., 1983).

Realgar AsS

Realgar has been found in just a few specimens at the Molinello mine as granules and small masses in the veins of chert (Palenzona, 1991).

Reppiaite [[Mn.sup.2+].sub.5][([OH.sub.4]).sub.2][([VO.sub.4]).sub.2]

Reppiaite, a monoclinic hydroxyl-vanadate of manganese, was described as a new species from specimens collected at the Gambatesa mine (Basso et al., 1992). It was found in very small amounts as tiny crystals in fractures cross-cutting a hausmannite-tephroite carbonate-bearing assemblage. It is in places associated with native copper and caryopilite, and is related to the hydrothermal circulation of V-enriched and As-enriched fluids. Some specimens collected from the dumps in 2000 also show sussexite crystals. The reppiaite crystals, orange-yellow to red, are minute and tabular, flattened on (100), and with an irregular contour. Their dimensions seldom reach 1 mm. It was named after the village of Reppia, near the Gambatesa mine, and so far it has not been reported from any other locality.

Rhodochrosite [Mn.sup.2+][CO.sub.3]

Rhodochrosite is common in the Val Graveglia manganese deposits as small masses and vein filling, and also as fine specimens with crystals up to 8 mm and as spherical aggregates up to 3 cm in diameter, covering fracture walls or crystals of other minerals. Among the best finds are the crystals collected at the Gambatesa mine during the 1960's, many of them associated with barite and ganophyllite. Also of note are the rhodochrosite and ganophyllite specimens collected mainly in the middle 1980's in material from a large quartz vein encountered in the underground workings at the Molinello mine.

Some nice specimens were also collected in 1993 in the Cassagna open pit, when a faulted block of ore rich in cavities was encountered. In this case the mineral formed bright crusts and spherules associated with white barite and neotocite. Rhodochrosite is difficult to find now that mining has ceased because it weathers rather rapidly, turning from pink to black.

Rhodonite ([Mn.sup.2+],[Fe.sup.2+],Mg,Ca)[SiO.sub.3]

Rhodonite is one of the most abundant minerals in the district; huge masses were encountered during mining, in particular at the Gambatesa and Cassagna mines during the 1960's and at the Molinello mine in the mid- 1980's. Those masses, which have a high manganese content, were often exploited as ore. During the periods of intense activity beautiful specimens were found, with crystals up to 3 cm, in vugs and fractures. The crystals, very different from the large, stout ones from Franklin, usually have a tabular habit, but acicular crystals are also common.

The color is highly variable: commonly pink, but occasionally red, orange, yellow and even purple. For this reason some other manganese silicates were, in the past, assumed to be rhodonite. Analysis led to the recognition of some good specimens of marsturite and pyroxmangite. It is possible that further investigation of rhodonite-like minerals can lead to finds of more uncommon species.

Rhodonite is commonly one of the first minerals formed in the veins, in places followed by calcite, rhodochrosite, barite or copper, and by rare species such as pyrobelonite, tangeite and gamagarite.

Romanechite [(Ba,[H.sub.2]O).sub.2][([Mn.sup.4+],[Mn.sup.3+]).sub.5][O.sub.10]

This species is often referred to as the so-called "wad" masses, which frequently fill cavities in the manganese ore or in the chert at the borders of the manganese deposits.

Saneroite [Na.sub.2][([Mn.sup.2+],[Mn.sup.3+]).sub.10][Si.sub.11][VO.sub.34][(O H).sub.4]

Saneroite, a rare sodium and manganese silicate, was found for the first time at the Gambatesa mine as tabular triclinic crystals up to a few millimeters, associated with braunite and barite. The mineral is named after Edoardo Sanero (1901--1983), Professor of Mineralogy at the University of Genoa (Lucchetti et al., 1981; Antofilli et al., 1983). It shows strong pleochroism, color from yellow to deep orange, and easy cleavage.

After the first find at the Gambatesa mine more specimens were collected at the Molinello mine, sometimes even in some quantity, between 1985 and 1989. The crystals reach 1 cm, and are often associated with barite, rhodonite, ganophyllite and barite, and enclosed in calcite. Careful treatment with diluted HCl can expose good crystals.

Saneroite is not easy to distinguish visually from tiragalloite and medaite, which are much rarer.

Sarkinite [[Mn.sup.2+].sub.2]([AsO.sub.4])(OH)

Sarkinite, a rare arsenate, was originally found in Sweden at Harstigen in Pajsberg, and at langban, and at Franklin (Dunn, 1995--1996). In Val Graveglia sarkinite has been collected only a few times, first at the Gambatesa mine (Cortesogno et at., 1979) as yellow to orange prismatic crystals up to 1.5 cm long in rhodonite veins, sometimes with bementite and abundant neotocite. Other finds are known from both the Gambatesa and Molinello mines (Borgo et. al., 1988) with poorly formed crystals, associated with saneroite and filling thin veinlets. Good specimens were collected in 1999--2000 from the hausmannite ore of the Gambatesa mine. These specimens show 1--2 mm, well formed crystals of sarkinite associated with manganoan calcite crystals.

Selenium Se

Only one specimen of selenium to date has been collected on the dumps of Gambatesa mine; it shows sub-millimetric crystals on white quartz (Palenzona, 1996). The source of the selenium in this specimen is not clear, and could be related to post-mining contamination.

Silver Ag

Silver was recently described in a quartz and native copper vein at the Molinello mine (Borgo and Palenzona, 1988) as arborescent aggregates up to 1 cm.

Smythite [Fe.sub.13][S.sub.16]

Smythite has been found at the Molinello mine, as small metallic crystals, 1 mm or less, in veinlets cutting chert (Palenzona, 1996).

Spangolite [[Cu.sup.2+].sub.6]Al([SO.sub.4])[(OH).sub.12]Cl-3[H.sub.2]O

Spangolite is known from only one find, as nice sky-blue crystals associated with connellite, cuprite, arsenates and other copper minerals, in the cavities in fossil wood at the Cassagna mine (Palenzona, 1996).

Spessartine (?) [[Mn.sup.2+].sub.3][Al.sub.2][([SiO.sub.4]).sub.3]

Spessartine, a Mn-bearing member of the garnet group, was erroneously reported from the Cassagna mine by Pelloux (1919). In 1934 Pelloux himself published a correction of the reported data, identifying as tinzenite the mineral previously believed to be spessartine. Nevertheless this species still appears in some lists of the Val Graveglia minerals (Antofilli et at., 1983). No macroscopic specimens of this species were observed by the authors, but extremely small (10-30 [micro]m) granules, not exhaustively studied, have been reported by Cortesogno et al. (1979).

Sphalerite (Zn,Fe)S

Zinc is a rare element in Val Graveglia; apparently sphalerite has been found only a few times at the Gambatesa mine, associated with bornite, chalcopyrite and other sulfides.

Strontiopiemontite CaSr[(Al,[Mn.sup.3+],[Fe.sup.3+]).sub.3][Si.sub.3][O.sub.11]O(OH)

This member of the epidote group is the Sr analog of piemontite, with strontium replacing calcium; it was described for the first time from material found at the Cassagna and Molinello mines, as small (3--4 mm) dark red veins and [010] elongated prismatic crystals, associated with quartz, calcite, rhodochrosite, rhodonite and ganophyllite (Bonazzi et al., 1990). Strontiopiemontite looks like the more common piemontite; only an analysis can confirm the identification of this mineral, which is quite rare in comparison with piemontite.

Sulfur S

Only one specimen of sulfur has been found, in a braunite vein at the Molinello mine in 1986. It shows a 3-mm group of well-formed crystals, associated with manganoan calcite, neotocite and weathered alabandite (which is probably the source of this element).

Sursassite [[Mn.sup.2+].sub.2][Al.sub.3][(SiO).sub.4]([Si.sub.2][O.sub.7])[(OH). sub.3]

The rare silicate sursassite, reported from the Err Valley (Switzerland), New Brunswick (Canada) and some Japanese localities, has been found in quartz veins cutting the "lean ore" at the Molinello mine (Cortesogno et al., 1979; Antofilli et al., 1983), in association with tinzenite, ganophyllite and, in places, manganese oxides. It usually forms veins up to 1 cm thick, with acicular crystals ranging in color from cream to chestnut-brown to reddish brown. Vugs containing good freestanding crystals up to 4 mm, in places forming very elegant sprays, are not easy to find and even more difficult to collect without damaging the crystals, because the matrix, usually crossed by quartz-filled veins, is very hard and tends to break into small pieces. The best specimens were collected in the 1980's mainly from old workings. At the Gambatesa mine, fine sursassite has also been found, and some specimens collected in 1997 are among the best from Val Graveglia.

Sussexite [Mn.sup.2+][BO.sub.2](OH)

The manganese pyroborate sussexite was collected at the Gambatesa mine a few times, as pink to violet acicular crystals up to I cm long. Sussexite fills thin fractures and is associated with calcite, tephroite, rhodochrosite, sarkinite and reppiaite (Cortesogno et al., 1979).

Synchysite-(Ce) Ca(Ce,La)[([CO.sub.3]).sub.2]F

Tiny crystals have been collected at Pontori and Gambatesa, in association with quartz. The specimens from Pontori show an intimate growth of synchysite-(Ce) and bastnaesite-(Ce) (Borgo and Palenzona, 1988; Palenzona, 1996). A few specimens of a mineral containing REE, mainly Ce and Nd, with a very low degree of crystallinity, perhaps pseudomorphs after a monazite-like mineral, were also collected from the Gambatesa dumps.

Tangeite [CaCuVO.sub.4](OH)

Tangeite, an orthorhombic vanadate of calcium and copper, forms a series with conichalcite. It was found in nice crystals up to 3 mm at the Molinello mine in 1986 (Palenzona, 1987; Basso et al., 1989) and later very rarely, as dark green masses. Associations include pink to salmon-orange rhodonite, quartz, calcite, braunite and in places, brownish red pyrobelonite and lustrous black tabular crystals of crednerite. Dark green crystals of tangite in rhodochrosite and quartz veinlets were collected at the Gambatesa mine in 1999.

Tennantite [(Cu,Ag,Fe,Zn).sub.12][As.sub.4][S.sub.13]

Specimens belonging to the tennantite-tetrahedrite series, with As content largely dominant over Sb, were collected in quartz veins at the Molinello and Gambatesa mines (Antofilli et al., 1983; Borgo and Palenzona, 1988). The crystals are up to 5 mm, with distinct tetrahedral habit. Some small bronze masses associated with goldmanite, originally misidentified as arsenosulvanite, are actually tennantite. Tennantite is often weathered and associated with arsenates such as olivenite and chalcophyllite.

Tephroite [[Mn.sup.2+].sub.2][SiO.sub.4]

Tephroite, the Mn-member of the olivine group, has been collected since 1978 at the Gambatesa mine, as red to brown to greenish brown crystals often included in calcite and associated with rhodonite, rhodochrosite, sussexite and ganophyllite (Cortesogno et al., 1979; Antofilli et al., 1983). More recently, in the early 1990's, several tephroite specimens were found at the Gambatesa mine, as crystals up to 2 cm often included in calcite, associated with bementite. In this case the color can range from red-brown to greenish.

Tinzenite [(Ca,[Mn.sup.2+],[Fe.sup.2+]).sub.3][Al.sub.2][BSi.sub.4][O.sub.15](O H)

Tinzenite, a rare triclinic manganese silicate, was found for the first time in the Swiss Alps (Falotta and Parsettens near Tinzen, Graubunden); it is also known from Akatore, New Zealand (Pelloux, 1934; Hochleitner, 1999) and from South American localities. Tinzenite was found in extraordinary specimens at the Cassagna, Gambatesa, Molinello and Monte Bossea mines, in veins up to 20 cm thick and several meters long in chert (Antofilli et al., 1983). Tinzenite often completely fills the veins, but vugs with crystals were also encountered, especially in the larger veins and in the faulted zones.

The crystals are triclinic and usually form rosettes and botryoidal aggregates. The color varies from creamy yellow to orange-red. Tinzenite from Liguria is probably the best in the world. It is commonly associated with crystals of quartz, sursassite, rhodochrosite, calcite and, in places, with chalcocite, manganese oxides and harmotome.

Tiragalloite [[Mn.sup.2+].sub.4][As.sup.5+][Si.sub.3][O.sub.12](OH)

Another species for which Val Graveglia is the type locality is tiragalloite. The original material was collected in the 1970's at the Molinello mine (Gramaccioli et al., 1979; Gramaccioli et al., 1980) as small orange granules associated with medaite. The main characteristic of the crystal structure of tiragalloite is the presence of the arsenatotrisilicate ion, the first known example of nonisolated [AsO.sub.4] groups, with three tetrahedra based on Si and one based on As. This feature implies extreme hydrolysis-preventing physical and chemical conditions, rare in nature and probably related to low temperature and high concentration in solutions. Tiragalloite remained an extremely rare mineral at the Molinello mine which was, for several years, the only known world locality, until the middle 1980's, when good, small (about 1 mm) crystals were found at the Cassagna mine in a vein in the braunite ore, associated with medaite, quartz, calcite and ganophyllite (Borgo and Palenzona, 1988).

Other specimens have been collected, always in very small amounts, again at the Molinello mine, in particular in the last years of operation. At the Gambatesa mine some specimens were also found, in association with rhodonite or calcite. In this case the crystals, orange to yellow in color, are up to 7 mm.

Tiragalloite was later reported from Alpine manganese occurrences (Bedogne et al., 1993), but it is still a very rare species. The name of this mineral honors Paolo Onofrio Tiragallo (1905-1987), a well-known mineral collector from Genoa, later curator of the mineral collections at the Mineralogy and Petrography Department of the University of Genoa.

Titanite [CaTiSiO.sub.5]

Titanite has been found in chert fractures as small (less than 1 mm), colorless crystals with quartz, anatase and clinochlore at the Molinello mine.

Todorokite ([Mn.sup.2+],Ca,Mg)[[Mn.sup.4+].sub.3][O.sub.7]*[H.sub.2]O

Todorokite is one of the non-crystallized manganese oxides which form "wad" at Val Graveglia (Antofilli et al., 1983).

Tyrolite [[CaCu.sup.2+].sub.5][([AsO.sub.4]).sub.2]([CO.sub.3])[(OH).sub.4]*6[ H.sub.2]O

Tyrolite has been found rarely at the Cassagna mine, as small rosettes of green-blue crystals, associated with conichalcite, copper, cuprite and secondary copper minerals (Palenzona, 1991).

Vanadomalayaite [CaVOSiO.sub.4]

Vanadomalayaite is an extremely rare mineral for which the Gambatesa mine is the type locality. It occurred in veinlets cutting the chert which hosts the manganese ore. Associated with haradaite, calcite and quartz. It has been found as subhedral isolated crystals rarely exceeding 0.5 mm in size. The habit is prismatic, with a good (110) cleavage. It resembles a dark red titanite, being actually an analog of titanite, with V replacing Ti, and of malayaite, with V replacing Sn (Basso et al., 1994).

Volborthite [[Cu.sup.2+].sub.3][[V.sup.5+].sub.2][O.sub.7][(OH).sub.2]*2[H.sub.2] O

Volborthite was the first vanadium-bearing mineral described from Val Graveglia (Cortesogno and Galli, 1974; Antofilli et al., 1983). Widespread in the fossil woods, in particular at Cassagna mine, it was also found in the quartz veins, especially at the Scrava mine (Basso et al., 1988). It usually forms crusts and thin coatings covering up to several square centimeters on the walls of small fractures. It is also known in tabular crystals up to 2 mm and as rosettes and spherules up to 5 mm. The color ranges from greenish yellow to dark green, suggesting the possibility of variation in composition or of the possible association with other unidentified vanadium species. The presence of volborthite in the fossil wood is an indicator of interesting assemblages of native copper, cuprite, azurite, chalcocite and several arsenates such as arseniosiderite, cornwallite, cornubite and chalcophyllite.

Wroewolfeite [[Cu.sup.2+].sub.4]([SO.sub.4])[(OH).sub.6]*2[H.sub.2]O

Wroewolfeite was found as a secondary mineral at the Gambatesa mine, in a tinzenite vein, associated with chalcocite (C. Balestra, per. comm.).

Wulfenite [PbMoO.sup.4]

Wulfenite has been collected rarely in the mid-valley limestone quarries as tabular, yellow crystals up to 1 mm, associated with calcite and weathered sulfides.

Zalesiite [CaCu.sub.6][([AsO.sub.4]).sub.2]([AsO.sub.3]OH)[(OH).sub.6]*3[H.sub. 2]O

A calcium-rich mineral resembling species of the mixite group and orginally designated as "agardite-(Ca)" was found at the Cassagna mine in the chert surrounding fossil wood (Palenzona, 1966). This mineral was later found to be identical to the new species zalesiite.

A neodymium-rich mineral of this type was found in very small aggregates at the Cassagna mine (Balestra, (1996).

Zeunerite [Cu.sup.2+][([UO.sub.2]).sub.2][([AsO.sub.4]).sub.2]*10-16[H.sub.2]O

Zeunerite has been found just once in fossil wood at the Cassagna mine, as three small (about 1 mm), pale green crystals, two of which were used for analysis. At present just one crystal remains to represent this occurrence. The associations include volborthite, native copper, connellite, arsenates and other copper minerals (Palenzona, 1996).

Zircon [ZrSiO.sub.4]

Pink prismatic crystals of zircon about 1 mm long were recently found as inclusions in trondhjemitic granites found in sedimentary breccia near the village of Arzeno.

Unconfirmed species and unknowns

A mineral found sparingly as dark red, lustrous granules and small (less than 1 mm) cubic crystals has been tentatively described as "yamatoite" (Palenzona, 1991), a hypothetical Mn-end member of the garnet group (not an IMA approved species). This mineral was found at the Gambatesa mine, associated with green goldmanite, in calcite and rhodonite veins.

The names of a few species sometimes circulate among collectors and occasionally are reported in the local literature although they have not been determined with certainty. Among them: tenorite, "illite" and zinnwaldite (from basalt cavities in the Molana quarry), hyalophane (adularia-like crystals associated with barite), marokite and "axinite" (a group name; actually only two members of this group, manganaxinite and tinzenite, are reported from Val Graveglia).

At least a dozen unknown minerals have been found at Val Graveglia. Some of them might someday be recognized as new species, while some others will probably remain unknown, such as the Nd-rich zalesiite-like mineral from the Molinello mine mentioned above, or an Sb-containing acicular sulfosalt found in one specimen at the Gambatesa mine, which was accidentally destroyed during a microprobe analysis.

ACKNOWLEDGMENTS

The authors wish to thank the mineral clubs and individuals who provided information and documentation on the minerals and localities of Val Graveglia: Gruppo Mineralogico Coop. A. Negro, Genoa; Gruppo Mineralogico, Ferrania and Gruppo Mineralogico del Levante, Sestri Levante; collectors Gianluca Armellino, Corrado Balestra, Roberto Bracco, Marco Ciuffardi, Giorgio Corallo, Adriano Gotelli, Antonio Gandolfo, Fabio and Marco Esposito, Graziano Lizza, Stefano Lunaccio, Ignazio Mezzano, Alessandro Pozzi, Domenico Sirianni; Cristina Baroni and Pietro Marescotti who made available their thesis material, and especially to Professor Andrea Palenzona and Dr. Joel Brugger, who provided suggestions and help for this article, and to Roberto Appiani for his competent mineral photography work.

A special thanks to Adriana Pagano and Giovanna Marchesini for their constant moral support, typing and graphic work.

DEDICATION

This article is fondly dedicated to the memory of Leandro de Magistris (1906-1990), mineral collector, Honorary Curator of Minerals at the Natural History Museum of Genoa, and acute connoisseur of the Ligurian minerals, a source of encouragement and knowledge to a whole generation of collectors in the Genoa area.

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Table 1.
Occurrences of some rare minerals from Val Graveglia
                                        Bakerite  Bementite
Val Graveglia, Italy                        *         *
Franklin and Sterling Hill, New Jersey      *         TL
Langban and Pajsbeg, Sweden                           *
Kalahari and Postmasburg, RSA                         *
Kombat Mine, Namibia
Val Ferrera and Oberhalbstein,
Switzerland                                 *
                                        Caryopilite  Crednerite
ValGraveglia, Italy                          *           *
Franklin and Sterling Hill, New Jersey       *
Langban and Pajsbeg, Sweden                 TL
Kalahari and Postmasburg, RSA                *
Kombat Mine, Namibia                                     *
Val Ferrera and Oberhalbstein,
Switzerland
                                        Gamagarite  Ganophyllite
ValGraveglia, Italy                         *            *
Franklin and Sterling Hill, New Jersey                   *
Langban and Pajsbeg, Sweden                              TL
Kalahari and Postmasburg, RSA               TL
Kombat Mine, Namibia                                     *
Val Ferrera and Oberhalbstein,
Switzerland
                                        Goldmanite  Kutnahorite
ValGraveglia, Italy                         *            *
Franklin and Sterling Hill, New Jersey      *            *
Langban and Pajsbeg, Sweden                              *
Kalahari and Postmasburg, RSA               *
Kombat Mine, Namibia                                     *
Val Ferrera and Oberhalbstein,
Switzerland
                                        Marsturite  Neotocite
ValGraveglia, Italy                         *           *
Franklin and Sterling Hill, New Jersey      TL          *
Langban and Pajsbeg, Sweden                            TL
Kalahari and Postmasburg, RSA
Kombat Mine, Namibia
Val Ferrera and Oberhalbstein,
Switzerland
                                        Palenzonaite  Parsettensite
ValGraveglia, Italy                          TL             *
Franklin and Sterling Hill, New Jersey
Langban and Pajsbeg, Sweden
Kalahari and Postmasburg, RSA                               *
Kombat Mine, Namibia
Val Ferrera and Oberhalbstein,
Switzerland                                  *             TL
                                        Pyrobelonite  Pyroxmangite
ValGraveglia, Italy                          *             *
Franklin and Sterling Hill, New Jersey       *             *
Langban and Pajsbeg, Sweden                  TL            *
Kalahari and Postmasburg, RSA
Kombat Mine, Namibia
Val Ferrera and Oberhalbstein,               *
Switzerland                                  *
                                        Saneroite  Sarkinite
ValGraveglia, Italy                        TL          *
Franklin and Sterling Hill, New Jersey                 *
Langban and Pajsbeg, Sweden                           TL
Kalahari and Postmasburg, RSA
Kombat Mine, Namibia
Val Ferrera and Oberhalbstein,
Switzerland                                 *
                                        Strontiopiemontite  Sussexite
ValGraveglia, Italy                             TL              *
Franklin and Sterling Hill, New Jersey                         TL
Langban and Pajsbeg, Sweden
Kalahari and Postmasburg, RSA                   *               *
Kombat Mine, Namibia                                            *
Val Ferrera and Oberhalbstein,
Switzerland
                                        Tephroite
ValGraveglia, Italy                         *
Franklin and Sterling Hill, New Jersey     TL
Langban and Pajsbeg, Sweden                 *
Kalahari and Postmasburg, RSA               *
Kombat Mine, Namibia                        *
Val Ferrera and Oberhalbstein,
Switzerland
TL = Type Locality
Table 2.
Species reported from the Val Graveglia Manganese District.
VC = very common, C =common, R = rare, VR = very rare,
(?) = doubtful, ill-defined, requiring further study etc.
NATIVE ELEMENTS
Copper                   Cu
Gold                     Au
Selenium                 Se
Silver                   Ag
Sulfur                   S
SULFIDES AND SULFOSALTS
Albandite                [Mn.sup.2+]S
Arsenosulvanite          [Cu.sub.3] (AsV) [S.sub.4]
Bornite                  [Cu.sub.5]Fe[S.sub.4]
Chalcocite               [Cu.sub.2]S
Chalcopyrite             CuFe[S.sub.2]
Covellite                CuS
Digenite                 [Cu.sub.9][S.sub.5]
Djurleite                [Cu.sub.31][S.sub.16]
Galena                   PbS
Marcasite                Fe[S.sub.2]
Orpiment                 [As.sub.2][S.sub.3]
Pyrite                   Fe[S.sub.2]
Pyrrhotite               [Fe.sub.1-x] S (x = 0-0.17)
Realgar                  AsS
Smythite                 [Fe.sub.13][S.sub.16]
Sphalerite               (Zn,Fe)S
Tennantite               [(Cu,Ag,Fe,Zn).sub.12] [As.sub.4][S.sub.13]
OXIDES
Anatase                  [TiO.sub.2]
Chalcophanite            (Zn,[Fe.sub.2+],[Mn.sub.2+])
                         [[Mn.sup.4+].sub.3][O.sub.7]*3[H.sub.2]O
Clednerite               CuMn[O.sub.2]
Cuprite                  [[Cu.sup.1+].sub.2]O
Goethite                 [alpha]-[Fe.sup.3+]O (OH)
Hematite                 [alpha]-[Fe.sub.2][O.sub.3]
Ilmenite                 [Fe.sup.2+][TiO.sub.3]
Magnetite                [Fe.sup.2+][[Fe.sup.3+].sub.2][O.sub.4]
Manganite                [Mn.sup.3+]O (OH)
Opal                     Si[O.sub.2]*n[H.sub.2]O
Pyrolusite               [Mn.sup.4+][O.sub.2]
Pyrophanite              [Mn.sup.2+][TiO.sub.3]
Quartz                   Si[O.sub.2]
Rancieite                (Ca,[Mn.sup.2+]) [[Mn.sup.4+].sub.4][O.sub.9]
                         3[H.sub.2]O
Romanechite              [(Ba, [H.sub.2]O).sub.2][([Mn.sup.4+],
                         [Mn.sup.3+]).sub.5] [O.sub.10]
Todorokite               ([Mn.sup.2+], Ca, Mg)[[Mn.sup.4+].sub.3]
                         [O.sub.7]*[H.sub.2]O
CARBONATES
Aragonite                Ca[CO.sub.3]
Azurite                  [[Cu.sup.2+].sub.3] [([CO.sub.3]).sub.2]
                         [(OH).sub.2]
Bastnaesite-(Ce)         (Ce, La) ([CO.sub.3])F
Calcite                  Ca[CO.sub.3]
Dolomite                 CaMg[([CO.sub.3]).sub.2]
Kutnahorite              Ca([Mn.sup.2+],Mg,[Fe.sup.2+])
                         [([CO.sub.3]).sub.2]
Malachite                [[Cu.sup.2+].sub.2]([CO.sub.3]) [(OH).sub.2]
Rhodochrosite            [Mn.sup.2+][CO.sub.3]
Synchysite-(Ce)          Ca(Ce,La)[([CO.sub.3]).sub.2] F
BORATES
Sussexite                [Mn.sup.2+][BO.sub.2](OH)
SULFATES, SULFITES
Barite                   Ba[SO.sub.4]
Brochantite              [[Cu.sup.2+].sub.4] ([SO.sub.4]) [(OH).sub.6]
Connellite               [[Cu.sup.2+].sub.19] [Cl.sub.4] ([SO.sub.4])
                         [(OH).sub.32] * 3[H.sub.2]O
Devilline                [[CaCu.sup.2+].sub.4][([SO.sub.4]).sub.2]
                         [(OH).sub.6] * 3[H.sub.2]O
Gravegliaite             [Mn.sup.2+] ([SO.sub.3]) - [3H.sub.2]O
Gypsum                   Ca[So.sub.4] * 2[H.sub.2]O
Langite                  [[Cu.sup.2+].sub.4] ([SO.sub.4]) [(OH).sub.6]
                         *2[H.sub.2]O
Posnjakite               [[Cu.sup.2+].sub.4] ([SO.sub.4]) [(OH).sub.6]
                         *[H.sub.2]O
Spangolite               [[Cu.sup.2+].sub.6] Al ([SO.sub.4])
                         [(OH).sub.12]Cl*3[H.sub.2]O
Wroewolfeite             [[Cu.sup.2+].sub.4] ([SO.sub.4]) [(OH).sub.6]
                         [2H.sub.2]O
Wulfenite                PbMo[O.sup.4]
PHOSPHATES, ARSENATES,
VANADATES
Arseniosiderite          [Ca.sub.2][[Fe.sup.3+].sub.3]
                         [([AsO.sub.4]).sub.3][O.sub.2]*[3H.sub.2]O
Chalcophyllite           [[Cu.sup.2+].sub.18][Al.sub.2]
                         [([AsO.sub.4]).sub.3][([SO.sub.4]).sub.3]
                         [(OH).sub.27]*33[H.sub.2])
Chernovite-(Y)           Y([AsO.sub.4])
Clinoclase               [[Cu.sup.2+].sub.3] ([AsO.sub.4])
                         [(OH).sub.3]
Conichalcite             [CaCu.sup.2+] ([AsO.sub.4]) (OH)
Cornubite                [[Cu.sup.2+].sub.5][([AsO.sub.4]).sub.2]
                         [(OH).sub.4]
Cornwallite              [[Cu.sup.2+].sub.5][([ASO.sub.4]).sub.2]
                         [(OH).sub.4]
Fluorapatite             [Ca.sub.5][([PO.sub.4]).sub.3]F
Gamagarite               [Ba.sub.2] ([Fe.sup.3+], [Mn.sup.3+])
                         [([VO.sub.4]).sub.2](OH)
Lavendulan               NaCa[Cu.sup.2+].sub.5] [([AsO.sub.4]).sub.4]
                         Cl-5[H.sub.2]O
Manganberzeliite         [(Ca, Na).sub.3][([Mn.sup.2+],Mg).sub.2]
                         [([AsO.sub.4]).sub.3]
Nabiasite                [BaMn.sub.9][[(V,As)[O.sub.4]].sub.6]
                         [(OH).sub.2]
Olivenite                [[Cu.sup.2+].sub.2]([AsO.sub.4])(OH)
Palenzonaite             ([Ca.sub.2]Na)[[Mn.sup.2+].sub.2]
                         [([VO.sub.4]).sub.3]
Parnauite                [[Cu.sup.2+].sub.9][([AsO.sub.4]).sub.2]
                         ([SO.sub.4])[(OH).sub.10]*7[H.sub.2]O
Pharmacosiderite         [[KFe.sup.3+].sub.4][([AsO.sub.4]).sub.3]
                         [(OH).sub.4]*6-7[H.sub.2]O
Pyrobelonite             Pb[Mn.sup.2+] ([VO.sub.4]) (OH)
Reppiaite                [[Mn.sup.2+].sub.5][([OH.sub.4]).sub.2]
                         [([VO.sub.4]).sub.2]
Sarkinite                [[Mn.sup.2+].sub.2] ([AsO.sub.4]) (OH)
Tangeite                 CaCu[VO.sub.4](OH)
Tyrolite                 Ca[[Cu.sup.2+].sub.5][([AsO.sub.4]).sub.2]
                         ([CO.sub.3])[(OH).sub.4]*6[H.sub.2]O
Volborthite              [[Cu.sup.2+].sub.3][[V.sup.5+].sub.2]
                         [O.sub.7][(OH).sub.2]*2[H.sub.2]O
Zalesiite                [CaCu.sub.6] [([AsO.sub.4]).sub.2]
                         ([AsO.sub.3]OH) [(OH).sub.6]*3[H.sub.2]O
Zeunerite                [Cu.sup.2+] [([UO.sub.2]).sub.2]
                         [([AsO.sub.4]).sub.2]*10-16[H.sub.2]O
NATIVE ELEMENTS
Copper                    C
Gold                     VR
Selenium                 VR
Silver                   VR
Sulfur                   VR
SULFIDES AND SULFOSALTS
Albandite                 R
Arsenosulvanite          VR
Bornite                   R
Chalcocite                C
Chalcopyrite              C
Covellite                 R
Digenite                  R
Djurleite                 R
Galena                   VR
Marcasite                 C
Orpiment                 VR
Pyrite                    C
Pyrrhotite               VR
Realgar                  VR
Smythite                 VR
Sphalerite               VR
Tennantite                R
OXIDES
Anatase                  VC
Chalcophanite            (?)
Clednerite               VR
Cuprite                   C
Goethite                 VC
Hematite                 VC
Ilmenite                  R
Magnetite                 C
Manganite                 R
Opal                     VR
Pyrolusite               VC
Pyrophanite              VR
Quartz                   VC
Rancieite                 C
Romanechite               C
Todorokite                R
CARBONATES
Aragonite                 R
Azurite                   C
Bastnaesite-(Ce)         VR
Calcite                  VC
Dolomite                  C
Kutnahorite               C
Malachite                VC
Rhodochrosite             C
Synchysite-(Ce)          VR
BORATES
Sussexite                VR
SULFATES, SULFITES
Barite                   VC
Brochantite               C
Connellite               VR
Devilline                 R
Gravegliaite             VR
Gypsum                    C
Langite                   R
Posnjakite                R
Spangolite               VR
Wroewolfeite             VR
Wulfenite                VR
PHOSPHATES, ARSENATES,
VANADATES
Arseniosiderite          VR
Chalcophyllite           VR
Chernovite-(Y)           VR
Clinoclase               VR
Conichalcite              R
Cornubite                VR
Cornwallite              VR
Fluorapatite             VR
Gamagarite                R
Lavendulan                R
Manganberzeliite         VR
Nabiasite                VR
Olivenite                 R
Palenzonaite             VR
Parnauite                VR
Pharmacosiderite         VR
Pyrobelonite             VR
Reppiaite                VR
Sarkinite                VR
Tangeite                 VR
Tyrolite                 VR
Volborthite               R
Zalesiite                VR
Zeunerite                VR
SILICATES
Albite                     NaA[Si.sub.3][O.sub.H]                 VC
Allophane                  Amorphous hydrous aluminum silicate     C
Andradite                  [Ca.sub.3][Fe.sub.2][(Si[O.sub.4]).     R
                           sub.3]
Bakerite                   [Ca.sub.4][B.sub.4]([BO.sub.4])        VR
                           [([SiO.sub.4]).sub.3][(OH).sub.3]
                           *[H.sub.2]O
Bementite                  [Mn.sup.2+].sub.8][Si.sub.6][O.sub.     C
                           15][(OH).sub.10]
Braunite                   [Mn.sup.2+][[Mn.sup.3+].sub.6]Si       VC
                           [O.sub.12]
Carpholite                 [Mn.sup.2+][Al.sub.2][Si.sub.2]         R
                           [O.sub.6][(OH).sub.4]
Caryopilite                [([Mn.sup.2+],Mg).sub.3][Si.sub.2]      C
                           [O.sub.5][(OH).sub.4]
Chrysocolla                [([Cu.sup.2+],Al).sub.2][H.sub.2]      VC
                           [Si.sub.2][O.sub.5][(OH).sub.4]
                           *n[H.sub.2]O
Clinochlore                [(Mg,[Fe.sup.2+]).sub.5]A1([Si.sub.3]  VC
                           Al)[O.sub.10][(OH).sub.8]
Clinochrysotile            [Mg.sub.3][Si.sub.2][O.sub.5]           C
                           [(OH).sub.4]
Datolite (?)               [Ca.sub.2][B.sub.2][Si.sub.2]          (?)
                           [O.sub.8][(OH).sub.2]
Diopside                   CaMg[Si.sub.2[[O.sub.6]                 C
Epidote                    [Ca.sub.2][([Fe.sup.3+],A1).sub.3]     VC
                           [(Si[O.sub.4]).sub.3](OH)
Fluorapophyllite           K[Ca.sub.4][Si.sub.8][O.sub.20]        VR
                           (F,OH].[8H.sub.2]O
Ganophyllite               [(K,Na).sub.2][(Mn,Al,Mg).sub.8]       VC
                           [(Si,Al).sub.12][O.sub.29-]
                           [(OH).sub.7].8-9[H.sub.2]O
Goldmanite                 [Ca.sub.3][(V,Al,[Fe.sup.3+]).sub.2]   VR
                           [(Si[O.sub.4]).sub.3]
Haradaite                  [Sr.sub.2][[V.sup.4+].sub.2]           VR
                           ([Si.sub.4][O.sub.12])
Harmotome                  [([Ba.sub.0.5],[Ca.sub.0.5],            C
                           K,Na).sub.5][[Al.sub.5][Si.sub.11]
                           [O.sub.32]]*12[H.sub.2]O
Hausmannite                [Mn.sup.2+][[Mn.sup.3+].sub.2]          C
                           [O.sub.4]
"Hornblende"                                                       R
Inesite                    [Ca.sub.2][[Mn.sup.2+].sub.7]          VR
                           [Si.sub.10][O.sub.28][(OH).sub.2]*
                           5[H.sub.2]O
Johannsenite               Ca[Mn.sup.2+][Si.sub.2][O.sub.6]        C
Manganaxinite              [Ca.sub.2][Mn.sup.2+][Al.sub.2]         R
                           B[Si.sub.4][O.sub.14](OH)
Marsturite                 [Na.sub.2]Ca[[Mn.sup.2+].sub.3]        VR
                           [Si.sub.5][O.sub.14](OH)
Medaite                    [([Mn.sup.2+],Ca).sub.6]([V.sup.5+])   VR
                           [Si.sub.5][O.sub.18](OH)
Montmorillonite            [(Na,Ca).sub.0.3][(Al,Mg).sub.2]        C
                           [Si.sub.4][O.sub.10][(OH).sub.2]*
                           n[H.sub.2]O
Neotocite                  ([Mn.sub.2+],[Fe.sup.2+])Si[O.sub.3].   C
                           [H.sub.2]O (?)
Nimite (?)                 [(Ni,Mg,[Fe.sup.2+]).sub.5](Al          R
                           ([Si.sub.3])[O.sub.10][(OH).sub.8]
Orthoclase                 KAl[Si.sub.3][O.sub.8]                  C
Parsettensite              (K,Na,Ca)[(Mn,Al).sub.7][Si.sub.8]     R?
                           [O.sub.10][(OH).sub.8][O.sub.20]
                           [(OH).sub.8]*2[H.sub.2]O
Pennantite                 [[Mn.sup.2+].sub.5]Al([Si.sub.3]Al)     R
                           [O.sub.10][(OH).sub.8]
Piemontite                 [Ca.sub.2](Al,[Mn.sup.3+],[Fe.sup.3+]   C
                           ).sub.3]
Prehnite                   [Ca.sub.2],[Al,sub.2][Si.sub.3]        VC
                           [O.sub.10][(OH).sub.2]
Pumpellyite-(Mg)           [Ca.sub.2]Mg[Al.sub.2](Si[O.sub.4])     C
                           ([Si.sub.2][O.sub.7])[(OH).sub.2]*
                           [H.sub.2]O
Pumpellyite-([Mn.sup.2+])  [Ca.sub.2]([Mn.sup.2+],Mg)[(Al,        VR
                           [Mn.sup.3+],Fe).sub.2](Si[O.sub.4])-
                           ([Si.sub.2,[O.sub.7])[(OH).sub.2]*
                           [H.sub.2]O
Pyroxmangite               [Mn.sup.2+]Si[O.sub.3]                  R
Rhodonite                  ([Mn.sup.2+],[Fe.sup.2+]Mg,Ca)Si       VC
                           [O.sub.3]
Saneroite                  [Na.sub.2][([Mn.sup.2+],[Mn.sup.3+]).   R
                           sub.10][Si.sub.11][VO.sub.34][(OH).
                           sub.4]
Spessartine (?)            [[Mn.sup.2+].sub.3][Al.sub.2]          (?)
                           [(Si[O.sub.4]).sub.3]
Strontiopiemontite         CaSr(Al,[Mn.sup.3+],[Fe.sup.3+]).       R
                           sub.3][Si.sub.3][O.sub.11]O(OH)
Sursassite                 [[Mn.sup.2+].sub.2][Al.sub.3]           C
                           [(SiO).sub.4]([Si.sub.2][O.sub.7])
                           [(OH).sub.3]
Tephroitc                  [[Mn.sup.2+].sub.2]Si[O.sub.4]          R
Tinzenite                  (Ca,[Mn.sup.2+],[Fe.sub.2+]).sub.3]     C
                           [Al.sub.2]B[Si.sub.4][O.sub.15](OH)
Tiragalloite               [[Mn.sup.2+].sub.4][As.sup.5+]B        VR
                           [Si.sub.3][O.sub.12](OH)
Titanite                   CaTiSi[O.sub.5]                         R
Vanadomalayaite            CaVOSi[O.sub.4]                        VR
"Yamatoite" (?)                                                   VR
Zircon                     ZrSi[O.sub.4]                           R
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Author:Marchesini, Marco; Pagano, Renato
Publication:The Mineralogical Record
Article Type:Statistical Data Included
Geographic Code:4EUIT
Date:Sep 1, 2001
Words:18519
Previous Article:MINERAL SPECIMEN MORTALITY.
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