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The Kipushi Mine, Zaire.

Kipushi is famous as a rich pipe-like deposit of zinc, copper and associated rare metals. Bearing similarities to Tsumeb, and situated near the Shaba Crescent, it has yielded many valuable specimens. Kipushi is the type locality for renierite and kipushite and the joint type locality (with Tsumeb) for briartite and gallite. It was also among the first known occurrences of veszelyite. Recently, nice rosettes of reichenbachite have been found as pseudomorphs after kipushite.

INTRODUCTION

Several authors (Cahen, 1954; Picot et al., 1963) have emphasized the presence in the late Precambrian rocks of South Central Africa of a polymetallic province, distinct from the stratiform Cu-Co-U seams of the copperbelts, and situated at a higher stratigraphic level in the Katanga System or its equivalents. This province includes deposits of Zn-Pb-Cu with an array of associated metals including Ag, Mo, W, Ge and Ga. Hughes (1979) points out that Tsumeb belongs to a unique group of orebodies of similar age, which are widespread around the Angola-Congo craton, examples being M'Passa in the People's Republic of the Congo and Kipushi in southeastern Shaba. Orebodies of this group show similarities to deformed Mississippi Valley-type deposits. Tsumeb and Kipushi are by far the most renowned occurrences of this type. They are sometimes called "sister deposits" (de Magnee and Francois, 1988); moreover, they are located in a similar hydrogeological environment. Another rare feature is that Tsumeb is iron-poor, which allowed copper ions to remain longer in solution, cementation having taken place rather sparingly. In addition, the circulation of supergene fluids was not hampered by infillings, crests or inclusions of iron oxi-hydroxides (Keller, 1984). The major difference in the extent of oxidation of primary ore explains the drastic difference in collector significance between Tsumeb and the less oxidized Kipushi. On the other hand, Kipushi has supplied material of choice to scientists, who have been able to study the phase relationships in relatively undisturbed primary sulfides, and thereby complete studies begun in Tsumeb (Deutzmann, 1961; Viaene and Moreau, 1968; Moh, 1973 and others), which are not without contradictions (Keller, 1977, 1984).

The Broken Hill deposit at Kabwe in central Zambia is also famous economically. Hosted just outside the Katangan rocks, it is interesting in comparison because of its rare copper-zinc minerals; this is mainly a zinc deposit, containing only about 0.035% copper (Mennell, 1920; Notebaart and Korowski, 1980).

LOCATION AND ACCESS

The locality is situated 28 km S60 [degrees] W of Lubumbashi, 5 km to the south of the Shaba Crescent (Gauthier et al., 1989), the northern portion of the Lufilian Arc wherein the tectonic structures are generally rich in stratiform mineralizations. The outcrop is only 500 meters from the Zambian border, represented by the crest line separating the basins of the Zaire and Zambezi rivers [ILLUSTRATION FOR FIGURE 1 OMITTED]. The tarred road from Lubumbashi is excellent, having been modernized during the early 1980's. On the Zambian side, Kipushi is connected by a good road to the old Kansanshi mine and the neighboring Solwezi town, about 100 km S60 [degrees] W [ILLUSTRATION FOR FIGURE 2 OMITTED]. This border road has historical significance. Kipushi-Zambia is a much smaller town than Kipushi-Zaire, the two cities being separated by a control post with customs and immigration. During the Katanga secession war in 1960-63, these localities played a strategic role because of their location and connections.

HISTORY

As with many copper deposits cropping out in the region, the history of Kipushi traces back to the Bantu tribes who settled in that part of Africa during the 4th century A.D., and displaced the Neolithic populations to the Kalahari (this timing being confirmed by Korowski and Notebaart, 1978). The settlers had already learned the technology of iron; the Bronze Age is missing here as a distinct period of civilization. The metallurgy of copper and the technology of iron have been utilized at the same time (Gauthier et al., 1989), though not by the same persons. The art of forging was always endowed with a touch of mysticism. Trade (in copper and other products) was established with the East Coast soon after the settlement of Arabs during the 7th century, but trading had probably begun earlier inside the continent. Trading with the West Coast didn't begin before the 16th century, after settlement by the Portuguese.

Following the European expeditions of the second half of the past century, the Kipushi deposit was discovered in August of 1899 by George Grey, chief of the first prospecting mission to the Zambezi-Congo border organized by Robert Williams' Tanganyika Concessions Ltd. (T.C.L.). In fact, they went on trying to locate the richest (gold) deposits in order to establish the path of the planned Cecil Rhodes Cape-to-Cairo railway. Employing indigenes as guides, Grey came from the copperbelt of Zambia, where he had already pinpointed a deposit, and went on to establish temporarily the headquarters of the T.C.L. in Kansanshi, which seemed an ideal advanced post for the exploration of Katanga. Being of the Shaban type, though situated far to the south of the Shaba Crescent, Kansanshi was spectacular but not heavily mineralized. The outcrops of the Zambian type were less exciting, only one (other than Kansanshi) having been exploited before the early 1930's (Korowski and Notebaart, 1978).

On instructions of the Special Katanga Committee of King Leopold II (Gauthier et al., 1989), Kipushi was visited in 1902 by the Belgian mineralogist Henri Buttgenbach, also with local indigenes serving as guides.

In 1915, the Kipushi district was delineated by the famous prospector Major R. R. Sharp, who had discovered the Shinkolobwe deposit a few months before. Sharp had been a prospector for the T.C.L., and became an employee of the Union Miniere du Haut-Katanga (U.M.H.K.) after its creation in 1906. The problem was to determine on which side of the border Kipushi was situated. It required checking the flow of all the local streams "inch by inch." Kipushi was thereby established as being within the Belgian Congo.

In early 1922 the U.M.H.K. sent a mission to evaluate the deposit, an assignment which became a difficult task for employees who had been city-dwellers and metallurgists but not prospectors. Only the local indigenes knew the footpaths which snaked through the bush, particularly at the apogee of the rainy season. After wandering in circles, members of the team had to ask some of their servants to climb trees in order to finally locate the small clearing in an ocean of greenery. Unlike other outcrops, which appeared as large, irregularly shaped hills without trees, the Kipushi site here was limited in size and situated in a karstic depression, more precisely in the eastern part of its floor and on its eastern wall. (This depression corresponded to the brecciated zone cropping out to the west of the mineralized area.) Exploitation followed, Kipushi soon producing the basic feedstock for the Lubumbashi smelter, and continuing to do so until recent years. Production in the other mines of the southeastern sector was limited to small amounts of oxidized ore. A concentrator was built in 1935 and, because sphalerite had become a contamination problem for the smelter, differential concentrations were achieved. The crude sphalerite concentrates were exported until 1954, when a facility specifically for refining zinc and cadmium became operational at Kolwezi. Separation of sphalerite allowed not only the recovery of a new valuable metal, but it also reduced the quantity of coal that had to be imported from Wankie, Rhodesia. Furthermore, grilling of the sphalerite concentrates in the roasting furnaces of a special chemical plant in Likasi permitted the recovery of sulfur for manufacturing the sulfuric acid used in the lixiviation plants, and thus reduced importation from South Africa.

Exploitation down to the 700-meter level has produced a total of 14 million tons of ore with an average content of 18% zinc, 10% copper, 1% lead and 60 g/ton silver (Intiomale and Oosterbosch, 1974). The total potential production is estimated at 10 million tons zinc, 5 million tons copper, 400,000 tons lead, 45,000 tons cadmium and 120 tons germanium, plus other rare metals recovered at a second refining site outside Zaire. For comparison, the production of Tsumeb, from 1906 to 1984, has been evaluated at approximately 20 million tons of ore from which were recovered some 2.5 million tons lead, 1 million tons copper and 850,000 tons zinc (Keller, 1984). When the pioneer geologist Jules Cornet stated in 1894 that Katanga was a "geological scandal" (Gauthier et al., 1989), he had not been aware of the richness of Kipushi, or even of its existence.

MINE WORKINGS

The general rule followed elsewhere in Shaba that ore containing 3.5% copper is at the limit of profitability in underground mining is not applicable at Kipushi. If the deposit had to be re-exploited today, it would still be as an underground mine, despite the mechanized shovels and other heavy equipment now available.

Exploratory workings were begun at the end of 1922 and by 1930 had been carried out down to level 40 by subcontractors. A pillar of low-grade oxidized ore was left in place adjacent to shafts sunk in the stable rocks of the middle Kakontwe (to the side of the footwall). The "open pit" was then partially filled back to the level of the original floor. No attempts were made to recover the totality of superficial ore (cropping out or not), because room was needed for processing plants. Ore became more interesting with depth, especially the masses of cementation chalcocite; two dumps of oxide ore were left behind after sorting out. An ancient exploratory incline through the pillar was kept intact and even later re-timbered. Joining the ventilation shaft, it served as a passage for pipes carrying compressed air and tailings (employed to fight fires in ancient timberings and later to backfill the large sublevel stopes).

The first preparatory workings were carded out in 1924-25: sinking of shaft I for hoisting, of shaft II for service and digging out of the crosscut tunnels at levels 65 and 100, followed by preliminary workings (in ore) which initiated underground production in 1926. There were also the ventilation shaft (III) to the north and the water pumping shaft (IV) to the south. Shafts I and II descended to level 500, and from there ore and men were relayed by shafts I-b and II-b. The ventilation shaft had to follow the trend of the vein, and eventually involved successive portions of old workings with variable slopes, added level by level. Shaft IV, which also served as a passage for the electrical cables, was continuous to depth, successive pumping stations having been constructed at selected levels. The distance between levels was initially 35 meters and later 50 or 60 meters.

Underground exploitation was begun from level 65 upward to level 40, with complete timbering and backfilling by the square-set method. This was changed to top-slicing from level 100 downward. The new technique, based on the removal of horizontal descending 3-meter slices, was well-adapted to maximum recovery of high-grade ore from the main body. Timbers were still used, and served as flooring, in continuous descent. Backfilling was no longer necessary, thanks to the steeply dipping lode.

Fires in old wood layers have long been a hazard to ventilation (which was probably the weakest aspect of the overall mining plan); work had to be suspended several times for up to a month. The top-slicing technique was improved around the 1960's, timbering being replaced by a supple metallic support laid in place beforehand. It was made up of a lattice work of crossed sheet-iron strips covered by a wire netting, supported by reusable shores with cotter pins.

No satisfactory method had been found for recovering the offshoots of low-grade ore until the early 1950's. The solution came with sublevel caving, started in 1954, for the Zn-rich lenses, from level 400 downwards. It produced large holes involving an entire level, 50 meters in height, which had to be backfilled to prevent air blasts and other hazards.

From about 1965-1975, Gecamines was willing to maximize the production. A new multipurpose shaft (V) was sunk and equipped by South African technicians directly down to level 1150,2 km east of the lode, in stable Kakontwe rocks and outside the old mine buildings and houses. It was accompanied by a wet-milling plant connected by a pipeline to the concentrator. The bottom of this shaft was connected with the workings by a so-called tunnel V. The water flow was so great that the tunnel had to be constructed with two inclined portions (with a summit in its middle) for drainage, half going to shaft V and half to the ancient pumping stations. By that time, top-slicing had been progressively replaced by sublevel sloping, with the introduction of fuel-powered tracks. In 1993, exploitation had reached at least level 1200, and other workings extended still deeper, ore having been recognized at least as deep as level 1500.

With regard to specimen recovery, collectors have only been allowed to go over the old dumps containing material from the superficial levels or made up of relatively barren Kakontwe rock from levels above 400, wherein the occasional interesting mineralized block could sometimes be discovered by chance. The most persistent collectors eventually operated by night, or with (exceptional) permission, on the pillar and even in the incline. Except for the discovery of kipushite, made by collectors, the locality has been curiously silent for the last 15 years or so, probably due to the absence of motivated collectors, and the legend that the sulfides are only massive. In addition to the underground levels, the open workings on the site of the outcrop will probably be rewarding places to collect specimens.

As of mid-1994 the Gecamines operation had almost come to a halt, but Kipushi was still alive; the pumps were still operating, and small amounts of sphalerite were being mined for production of sulfuric acid. Much of Kipushi's richness remains on the tailings and slag heaps.

GEOLOGY

The regional geology has been reviewed by Francois (1987) in a comprehensive synthesis, surveyed by Gauthier and Francois (1989) In a following paper, Francois (in de Magnee and Francois, 1988) has laid particular stress on the role played by Roan evaporites and their diapiric ascent in various kinds of tectonic ruptures of the Kundelungu covering, followed by collapse brecciation, to explain peculiarities like the dislocation of the three lower Roan groups in a megabreccia and the cropping out of this megabreccia as fragments, often of large size, which can be mingled with blocks of the Kundelungu Supergroups, as in cases of partial scraping of an anticline flank. Also stressed is the role played by hot brines resulting from the solution of evaporites as mineralizing fluids, especially in epigenetic post-tectonic deposits like Kipushi.

Kipushi

To the south of the Lufilian arc, the anticlines become successively rarer in R2 (Roan) fragments. The Kipushi uplifted anticline straddles the border for a distance of 25 km, trending N60 [degrees] W. Its axial core is filled with a megabreccia belonging in all likelihood to the R3 group. It ends at the Kipushi site where a huge portion of its northern flank, some 1800 meters in length and 200 meters in depth, has been tom away and replaced by a megabreccia. Toward the east, the breccia is in contact with a discontinuity surface dipping N70 [degrees] W. The Kipushi fault exposes from south to north the normal stratigraphic succession from the lower R4 group to the upper part of the Lower Kundelungu Supergroup. The latter is present here as a southern facies, rich in permeable carbonate beds which deliver important quantities of water and are subject to karstification, ancient and recent.

Above the Ki 1.2.2 member, "Calcaire de Kakontwe" (more simply Kakontwe), lies the "Serie Recurrente," a name given by miners to a banded alternation of silty dolomitic shales and dolostones, a member seen only in underground mine workings. Both form the footwall of the orebody, together with some breccia in the south. The Kakontwe, mostly made up of limestones in its southern facies, is heavily dolomitized over a distance of 200 meters from the lode, and to a lesser extent quartzified as a result of reworking of the country-rock before deposition of sulfides (Thoreau, 1928, and Hughes, 1979, for Tsumeb), and weak metamorphism (de Magnee and Francois, 1988). The early "feldspar-quartz-mica phase" of Thoreau (1928) cropped out as a chloritic breccia and enlarged the network of fissures in the Kakontwe. These openings later became lined with secondary gangue minerals, as seen particularly in fantastic caves and crystal-covered walls encountered during preparatory work near the lode. The roof of the orebody is formed by the "Grand Lainbeau," a gigantic slice of stratified dolomitic and silty shales belonging to one of the Kundelungu Supergroups, a fragment of the anticline flank before its rupture (Intiomale and Oosterbosch, 1974). This impermeable roof, up to 250 meters thick and 500 meters long, is more or less continuous between the 200 and 1800-meter levels. Its stratification is nearly parallel to the bedding of the Kakontwe, dipping 70 [degrees] to 80 [degrees] NE. The Kipushi fault and the Grand Lambeau were the structures which channelized the ascension of the mineralizing fluids into a narrow space during the period of mineralization. Two horizontal tunnels terminated by drill holes at level 240 and 1150 have penetrated the megabreccia and crossed slabs of saussuritized gabbro (Intiomale and Oosterbosch, 1974). It does not appear igneous rocks were intruded at that time, but rather were present beforehand in the R3 group.

Features of the Deposit and Mineralization

Like Tsumeb, the Kipushi deposit is a typical ore-pipe, near-vertical, and irregular but roughly elliptical in cross-section. Unlike Tsumeb, it is composed mostly of massive ore and a few disseminated areas of low grade. It has an axial trend of N28 [degrees] E, is 200 to 600 meters long, and 20 to 60 meters thick (average 30 meters) with the maximum thickness at the top of the Kakontwe, where it forms the northern massif. The pipe follows the fault at every level, and dips 70 [degrees] NW (in a vertical cross section). This main portion of the orebody is rich in both zinc and copper sulfides, zinc ore becoming more and more segregated and predominating over copper ore in the lower levels.

Mineralization did not penetrate into the "Grand Lambeau" to any significant extent. On the contrary, three zones can be distinguished on the footwall: (1) In the "Serie Recurrente," over a stratigraphic distance (to the north) of 50 meters, where stratabound off-shoots have penetrated the more permeable shaley horizons over a distance of at least 100 meters, resulting in low-grade (about 2%) copper ore with just a trace of Zn; (2) In the upper Kakontwe, where the northern body is extended as off-shoots forming the so-called eastern apophysis, made up of low-grade zinc ore, with some lead; and (3) in the middle portion of the Kakontwe, where sphalerite-rich (to 40% Zn, with just traces of Cu and no Pb) appendicular pipes are often surrounded by a pyrite sheath, and invade the country-rock in a complex pattern branching laterally, upward and (mainly) downward (Ottenburghs, 1964), following a network of fissures and cavities that may be part of the network created by early brines. These latter are at least four in number, are well delineated, rounded or elliptical, and with cross-sections of 5 to 40 meters; they eventually connect to the main pipe. The longest could once be traced down to level 700, while the largest is still in place between levels 290 and 400. The oxidation zone reached level 120. Secondary sulfides are dominant down to level 250, but traces of oxidation-cementation are present to very great depth. The water table is at 85 meters. The zone of outcrop is rather limited in comparison to the horizontal extent of subsurface levels.

The average content of extracted ore (to level 700) was about 30% economic metals, 10% iron and 20% sulfur (Intiomale and Oosterbosch, 1974), or about 40% gangue.

Paragenesis

The literature that has issued from European institutions regarding complex sulfides in polished sections has been prolific. It began with a paper by Thoreau (1928), who had studied the first drill cores, and continued until about the mid 1970's, mainly at the School of Leuven, Belgium (Ottenburghs, 1964; Viaene and Moreau, 1968; Devos et al., 1974 and others). Most authors suggested a scheme of successive phases for deposition of primary sulfides, sphalerite having as a general rule, preceded copper sulfides and each phase having been accompanied by accessory metals, either as trace elements or as distinct species. Earlier-deposited minerals have been partially dissolved, their metals being possibly redeposited as other mineral species. Since Thoreau (1928), all authors have agreed that sulfides were deposited by metasomatism of carbonates and not by filling of voids, although the banded structure typical of this mode of deposition has rarely been encountered. On the contrary, ore samples appeared porous (Thoreau, 1928; Dimanche, 1974). Because deposition lasted over a long period, replacement has been progressive, first as a stockwork and then as eventual complete replacement of the gangue (Masuy, 1938). According to Devos (1973), and to observations on the numerous blocks of gangue which collectors had to split, only the last phase of ore reached the surface; upper levels remained at the stockwork stage. Deutzmann (1961), after studying hundreds of polished sections from the Tervuren Museum, concluded that there were two parageneses, one formed at a rather high temperature (corresponding to the first two phases of other authors, e.g. the pyrite-arsenopyrite phase with some chalcopyrite and the sphalerite phase) and another one formed at lower temperature (corresponding to the Cu-II or cuprozincian phase of others). Devos et al. (1974) summarized the general sequence: pyrite and arsenopyrite crystallized first, followed by sphalerite, then by chalcopyrite, tennatite and some germanium species (germanite, briartite) and finally by copper-rich sulfides (bornite, chalcocite) and renierite.

For the secondary minerals, a paragenetic sequence has not yet been established. The literature consists only of descriptions by early observers, which were summarized by Buttgenbach (1947). It seems logical that, as at Tsumeb (Keller, 1984), the supergene fluids followed the karstic channels, as evidenced by the gangue remnants. This could explain why the oxidation and cementation zones are quite extended in height, due to the presence of many gangue remnants in the very highest levels, and are also found as traces and pockets in depth. Examination of many specimens has confirmed this; these consisted of a matrix of one of the primary sulfides, like massive chalcopyrite, containing remnants of arsenopyrite crystals; and of a vug lined by iron oxides and quartz wherein crystals of a secondary mineral like hemimorphite had developed.

Dimanche (1974), who studied polished sections of ore from level 500, believed his samples had been modified by supergene alteration (as suggested by the presence of digenite, covellite and idaite).

MINERALS

The list in Table 1 is a compilation primarily of data from the literature, unpublished reports by the geological staff of the companies (U.M.H.K. and later Gecamines), specimens in the collections of the Tervuren Museum (courtesy of Dr. M. Deliens), and personal observations. It is probably far from complete; for example, arsenates must occur more abundantly than reported if one considers the quantity of As in primary ore. Several descriptions of new species are still in preparation. Devos et al. (1974) have reported a Ge-bearing sulvanite, and also V-bearing and W-bearing germanites, probably related to similar phases reported from Tsumeb by Pinch and Wilson (1977). There was also an incompletely characterized sulfide of Ga, Cu and Fe, a Ga-rich briartite and others.

Adamite [Zn.sub.2](As[O.sub.4])(OH)

Adamite has not previously been identified from Kipushi in the literature. Some years ago, however, collectors found a block of chalcopyrite showing traces of alteration; splitting this block revealed aggregates of yellow to white crystals since identified as adamite. Associations include hemimorphite, goethite and quartz. Six specimens were recovered from the find, including one good cabinet specimen.

Arsenopyrite FeAsS

Arsenopyrite, one of the earliest-formed sulfides, has been known from near-surface exposures since 1927 (Buttgenbach, 1947). Buttgenbach described twinning on (101) and (103); because the angle with the longitudinal axis is about 60 [degrees] in both cases, trillings about the y axis can result, as had been observed for the species by Dana in 1892.

Arsenopyrite is widespread as euhedral, silver-white crystals of long prismatic habit commonly up to 1 cm in size, and occasionally up to Several centimeters, as single crystals, rosettes and sprays. The terminations are rounded and transversely striated, but the longitudinal faces show no striations. Crystals in the dolomitic and quartzitic country rocks which have escaped corrosion or replacement by later sulfides are found unaltered, whereas crystals found with sphalerite, tennantite and chalcopyrite are corroded.

Atacamite [Mathematical Expression Omitted]

Atacamite has been known from Kipushi since 1928, in association with acicular cuprite. Buttgenbach noted the presence of the vicinal form t{17.20.9} on some specimens.

Aurichalcite [(Zn,[Cu.sup.2+]).sub.5][(C[O.sub.3]).sub.2][(OH).sub.6]

Aurichalcite has been recognized from Kipushi since 1923, as tufts of small, acicular crystals in a vug (Buttgenbach, 1947). Buttgenbach also reported that aurichalcite inclusions can impart a green color to hemimorphite. He noted intergrown fibrous masses to 6 cm in thickness, with individual needles 3 to 8 mm.

Fibrous masses of aurichalcite to 10 cm thick were collected in the early days of mining; these asbestiform masses have in some cases been hardened by the intimately mixed presence of hemimorphite.

Aurichalcite is common in the near-surface oxidation zone. During the 1970's collectors recovered substantial numbers of specimens from the oxide dumps and from blocks pulled down from the pillars. Associations commonly include colorless hemimorphite, and hemimorphite crystal aggregates colored blue or green by aurichalcite inclusions (as radiating fibrous spheres and as uniform impregnations). Mammillary crusts and isolated hemispheres are also encountered.

Azurite [Mathematical Expression Omitted]

Buttgenbach (1947) reported irregularly rounded azurite aggregates to 6 cm. Unlike malachite, azurite is rare in Katanga, Kipushi being one of the few occurrences. Even pseudomorphs of malachite after azurite are rare and especially prized by collectors. Crystals are generally not very sharp and are less than 1 cm in size. Azurite stalactites to about 1 cm were found during the early days of mining.

Betekhtinite [Cu.sub.10](Fe,Pb)[S.sub.6]

Betekhtinite, first reported from Kipushi by Deutzmann (1961), is widespread in the lower bornite zone on level 850, as large masses and scattered groups of acicular, blackish gray crystals to 2 cm. Betekhtinite is also found as blebby masses and veinlets in bornite-rich ore. Tennantite may also be present, but the most typical associations besides bornite are chalcocite or galena (but not both). The compositions of these minerals suggest that betekhtinite + bomite cannot be in equilibrium with chalcocite and galena at the same time, a conclusion born out by observation (Devos et al., 1974).

Bismuth Bi

Native bismuth has been found in isolated bodies at the margin of the deposit on the lower levels, along with complex bismuth sulfides. Trace amounts of bismuth have also been found in several sulfides, mainly tennantite and, to a lesser extent, sphalerite (Intiomale and Oosterbosch, 1974).

Bismuthinite [Bi.sub.2][S.sub.3]

Bismuthinite was reported by Devos et al. (1974) in iron-rich ore of the Cu-I type (chalcopyrite, pyrite, arsenopyrite) on level 575.

Bornite [Cu.sub.5]Fe[S.sub.4]

Massive primary bornite is the most abundant copper-bearing sulfide at Kipushi. It occurs as well-delineated zones in copper-rich ore, with a large extension in the upper levels (down to 400) and another one in the lower levels (around 850). From level 975 downward bornite disappears.

Crystals are rare, but many have probably escaped the attention of busy miners near the contact with the country-rock. Yet some good old-time specimens exist in collections as sharp rhombo-dodecahe-drons with their faces superficially altered to malachite, exhibiting a lattice of striations due to the alternating growth of cube faces, and with visible remnants of chalcopyrite on the cleavages.

Massive bornite is bronze-colored on fresh cleavages, which rapidly take on the iridescent "pigeon's breast" shades before becoming definitely blue. Sometimes bornite does retain its original color, whether crystallized or not. But in the workings, the color of the cuts is almost always uniformly blue, probably due to multiple fissures caused by blasting in neighboring areas.

Primary bornite is the main carrier of silver, and can contain up to 2,600 ppm as a trace element (Intiomale and Oosterbosch, 1974). It occurs in contact with all other sulfides, except pyrite and arsenopyrite. Supergene bornite is also present, but contains no silver (Intiomale and Oosterbosch, 1974).

In his study of samples from level 500, Dimanche (1974) reported bornite with variations in the Cu:Fe ratio; this variability is easily explained by the complex structure of bornite with its numerous vacant sites (Pierce and Buseck, 1978). The crystal system of borniteis still a matter of debate (Fleischer and Mandarino, 1995; Pierce and Buseck, 1978), the temperature of formation being of importance.

It appears that bornites from various Katangan deposits exhibit their own characteristic colors in collections.

Briartite [Cu.sub.2](Fe,Zn)GeS

Briartite was described as a new species by Francotte et al. (1965), and named for Gaston Briart, a pioneer geologist at Kipushi. A preliminary description of grains in Tsumeb ore had appeared earlier in an unpublished report of Geier in 1955 (Geier and Otteman, 1972), to which the working name "mineral W" was given, but no more such grains were observed for years.

At Kipushi the mineral was first described by Francotte in an unpublished report of 1962 (Francotte et al., 1965), and then by Ottenburghs (1964) in sphalerite from the appendicular pipes. For the original description, three specimens were used, plus a germanite from Tsumeb, and a renierite from Kipushi for comparison. Coincidentally, a briartite from Tsumeb was also included, which made Tsumeb a co-type locality.

Inclusions of briartite occur (in the Kipushi ore) in tennantite, chalcopyrite and sphalerite, but do not belong to the same paragenesis as renierite (Devos, 1973). The average size of inclusions is 0.1 to 0.3 mm but they can occasionally reach 2 mm. Their color is gray to bluish gray in natural light.

The tetragonal structure is related to that of sulfides with tetrahedral coordination, such as sphalerite, chalcopyrite, stannite and renierite. Chemically, briartite is the richest Ge-sulfide. It contains about 15% Fe and Zn, which can replace each other, resulting in Fe-rich and Zn-rich end-members, the former being the most abundant in Kipushi. A Ga-rich variety also probably exists (Devos et al., 1974).

Ottenburghs and Goethals (1972) succeeded in synthesizing the phases and found that at 700 [degrees] C there is a continuous solid solution between the two end-members. Above this temperature, synthetic briartite changes into an orthorhombic phase.

Briartite is a rare species of interest only to systematic collectors; no natural crystals have been found.

Brochantite [Mathematical Expression Omitted]

Brochantite has been known at Kipushi since 1924 (Buttgenbach, 1947). Crystals are acicular and of the typical green color, elongated along their c-axis, with a bevel termination composed of two {301} faces.

Calcite CaC[O.sub.3]

Calcite forms a noticeable part of the country-rock, where preparatory workings encountered walls and pockets lined with scalenohedrons to 6 cm. The constant association of (zincian) dolomite crystals on a matrix of carbonates covered by iron oxides indicates that the linings are secondary features. Specimens have always been difficult to remove intact because of the hardness of the matrix; limited blasting has usually been necessary.

Most calcite crystals are milky white, opaque to translucent, and commonly stained brown, orange or rod by iron oxides, although others are colorless with a honey or lilac tinge.

Unusual habits have also been found, like Buttgenbach's steep positive rhombohedrons {4041}, with their lateral edges replaced by the negative scalenohedron {2.24.27.71}. A cave produced elongated crystals referred to by collectors as "French fried" calcite. This is mainly due to a combination of the very sharp negative rhombohedron {0.11.11.1} passing over a curved zone to the acute the negative rhombohedron [0551], the termination being the negative rhombohedron {0112} (not exceeding a few mm) altered by the positive rhombohedron {1010}. These latter two forms were observed by Buttgenbach as crystal terminations. Originating from another pocket are the clusters of "calcite flowers," wherein the crystals, assembled as bunches, reach 1.5 cm. The predominating form here is the negative rhombohedron {0551} with the simple termination {0112}.

Also typical of Kipushi are the encrustation pseudomorphs or molds of dolomite after calcite, empty or still filled with calcite. Several occurrences with different crystal habits of calcite and different color stainings of the molds exist in collections. The most remarkable are yellow-coated (probably by zincite) pyramids to 7 cm, the surface of the coating being covered with a later generation of small dolomite crystals and with a seeding of transparent hemimorphite crystals 2 to 3 mm in size. No cobaltoan calcite has been reported from Kipushi.

Carrollite Cu[(CO,Ni).sub.2][S.sub.4]

Carrollite is rare at Kipushi, crystals to 5 mm having only once been observed.

Cerussite PbC[O.sub.3]

Cerussite occurs in limited areas of the oxidation zone. It was first described from Kipushi by Buttgenbach in 1923 (Buttgenbach, 1947) as sharp, milky white crystals, flattened on (010), with lustrous faces, isolated or assembled as trilling twins on (310), scattered on a carpet of malachite. According to Umba et al. (1977), crystals appear as sharp orthorhombic prisms to 1 cm, opaque or translucent white, with an adamantine luster and a complex habit, the prism being modified by several truncations of the edges and by multiple twinning.

It should be added that very often phantoms are delineated by growth lines parallel the lateral faces, with twinning clearly indicated by these lines and by re-entrant angles.

The best, original find came from a turret at level 50 in the old reconnaissance incline. During the late 1970's, when the incline was re-cut and re-timbered, more specimens were recovered. The pocket is not exhausted, but the place is very dangerous.

The association of malachite or pseudomalachite makes specimens aesthetically pleasing. Cerussite otherwise occurs quite dispersed. A veinlet of crystals on blue hemimorphite was once discovered, and pseudomorphs after cerussite have been observed on old-time vauquelinite specimens.

Chalcocite [Cu.sub.2]S

No significant crystals of Kipushi chalcocite exist in collections, though both Buttgenbach (1947) and Umba et al. (1977) report the occurrence of elongated prisms. The mineral is mostly secondary, as masses in the oxides and as veinlets in other sulfides. Hypogene chalcocite was reported by Deutzmann (1961). Chalcocite is said by Devos et al. (1974) to coexist in equilibrium with betekhtinite.

Chalcopyrite CuFe[S.sub.2]

Chalcopyrite is the second most abundant major copper sulfide. Large deformed crystals were reported by Buttgenbach (1947), but chalcopyrite most often occurs as massive, well-delineated bodies in the lower levels and as mixed ore with sphalerite and/or bornite in the higher levels. In copper-rich ore the zones of chalcopyrite and bornite are often independent from each other. Being entirely primary, chalcopyrite forms part of two paragenetic sequences (Deutzmann, 1961):

Chalcopyrite I occurs in an iron-rich assemblage deposited at a rather high temperature. This chalcopyrite is cleaner and doesn't tarnish. It is accompanied by pyrite, arsenopyrite, some pyrrhotite, tennantite (corresponding to the Cu-I phase of Devos, 1973), dark, iron-rich sphalerite and some galena.

Chalcopyrite II occurs as golden yellow, rapidly tarnishing material associated with sphalerite II, cleaner and iron-poor but richer in elements like Cd and Co, with some galena. It is accompanied by tennantite, renierite, bornite, galena, betekhtinite and chalcocite. This sequence, deposited at a lower temperature, corresponds to the Cu-II type mineralization of Devos (1973).

Chalcopyrite can contain up to 0.56% Co in solid solution, and is an important carrier of this element (Intiomale and Oosterbosch, 1974).

Chrysocolla [([Cu.sup.2+],Al).sub.2][H.sub.2][Si.sub.2][O.sub.5][(OH).sub.4][center dot]n[H.sub.2]O

Chrysocolla has been reported with veszelyite (Buttgenbach, 1947). Mammillary crusts of chrysocolla also underlie vauquelinite on old-time specimens. The vitreous chrysocolla is partly blue and partly gray-white, with an outlining banded structure. Like malachite, chrysocolla is not very significant from Kipushi, unlike in the Shaba Crescent.

Cobaltite CoAsS

Cobalt is an accessory element in Kipushi ore, cobaltite being the best represented species as grayish white masses with a metallic luster in chalcopyrite and/or bornite. Cobalt is present as a trace element in many sulfides besides chalcopyrite. In sphalerite, the cobalt content is particularly variable (Intiomale and Oosterbosch, 1974).

Copper Cu

Native copper occurs at the base of the oxidation zone, as masses and as poorly shaped crystals connected by a wire-like structure. At level 170, a tunnel crossed a pocket of concretionary smithsonite containing arborescent copper on a chalcocite matrix.

Cuprite [Cu.sub.2]O

Few crystals of cuprite are known from Kipushi except as the acicular habit, in association with gangue and other secondary ore minerals. Acicular crystals to 1 cm, with right-angle bends, are known on some of the older specimens.

Dolomite Ca,Mg[(C[O.sub.3]).sub.2]

Dolomite is the major component of the country rock at Kipushi. Twisted rhombs of the zinc-rich variety, informally called "zinco-calcite" by geologists (Umba et al., 1977) and collectors, are opaque, milky white to beige or brownish, up to 8 mm in size, and are abundantly present on specimens with secondary minerals. Zinc-rich dolomite crystals occur isolated or aggregated, sometimes as stalactites with a core of goethite, and also as various kinds of twins and rosettes to about 1.2 cm in diameter.

The formation of zincian dolomite is easily explained by the similar ionic radii of zinc and magnesium and by the solubility of Zn ions, which are easily leached down by supergene fluids. On the other hand, cobaltoan dolomite, which is widespread in the Shaba Crescent (Umba et al., 1977, describe only pink dolomite, but that was before the exploitation of Mashamba West), has not been reported at all from Kipushi (where the mineralization is post-tectonic).

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

Fluorapatite is a component of the country rock at Kipushi (Intiomale and Oosterbosch, 1974). Guillemin (1956) was of the opinion that phosphate leached from this mineral in the country rock was carried to the orebody by supergene fluids and accounts for the relative abundance there of secondary phosphate minerals.

Galena PbS

Galena is generally found as veinlets and small, brittle masses showing cubic cleavage, in or near the margins of all types of mineralization. Most of the lead at Kipushi was deposited as galena, and is present as barely a trace in other of sulfides. The deposition of galena seems linked to that of sphalerite in an early stage, as in the periphery of the off-shoots in the upper Kakontwe (eastern apophysis). Masuy (1938) reported replacement of galena by bornite. This author's view is that a great deal of galena went back into solution, and a second generation was then deposited as a halo around the copper-rich ore (Intiomale and Oosterbosch, 1974). Galena occurs in contact with almost all other sulfides and almost always appears younger. Small cubic crystals of galena have been reported since Thoreau (1928). Secondary galena was reported by Masuy (1938) in the overburden covering the Kakontwe.

Gallite CuGa[S.sub.2]

Gallite was originally described as a new species by Strunz et al. (1958), who had studied samples from Tsumeb. A short time before publication, a similar occurrence was brought to their attention in samples from Kipushi, which thus became a co-type locality. The presence of gallium in germanite from Tsumeb has been known since 1922 (Strunz et al., 1958). Gray grains and lamellae previously observed by several authors in germanite, renierite and other ore minerals were investigated by Strunz et al. (1958), who found primarily Cu and Ga in an atomic ratio of 1:1. The X-ray powder diffraction pattern was similar to that of chalcopyrite, which suggested that the formula might be CuGa[S.sub.2]. The authors were successful in synthesizing this compound, which presented an identical X-ray powder pattern.

In ore from Kipushi, needles and grains of gallite occur in sphalerite and in chalcopyrite as exsolution structures. Gallite from Kipushi contains Fe which partially replaces Ga. Ga is also found as a trace element in chalcopyrite and briartite. (An incompletely characterized sulfide of Cu, Ga and Fe found here is gray-purple and contains up to 13% Ga (Devos et al., 1974).) The average Ga content of Ge-rich ore from levels 725 to 775 is 0.25% (Intiomale and Oosterbosch, 1974); the distribution of gallium in ore parallels that of germanium (Devos et al., 1974; Intiomale and Oosterbosch, 1974).

Germanite [Cu.sub.26][Fe.sub.4][Ge.sub.4][S.sub.32]

Germanite is rare at Kipushi, even though it is the main Ge-bearing mineral at Tsumeb; according to the view of Viaene and Moreau (1968), this is because Kipushi is too iron-rich to allow the formation of much germanite, the Ge-sulfide with the lowest iron content. Devos et al. (1974) found germanite as an accessory species in both Ge-rich zones, their view being that germanite was deposited before renierite.

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

Iron oxi-hydroxides are abundant as a part of the matrix of most specimens containing secondary minerals. Pseudomorphs of limonite after pyrite are known from Kipushi, as from many places in Shaba. Radiating spherules of goethite are also common. Devos (1973) points out that goethite is present as supergene veinlets in all iron-rich types of mineralization.

Graphite C

Graphite is abundant and is sometimes found as large masses of the organically derived variety in the country rock and in gangue as well. Graphite from Kipushi contains structured remnants of "organites" (Devos, 1973).

Gypsum CaS[O.sub.4][center dot]2[H.sub.2]O

Gypsum as transparent needles to 2 cm is commonly associated with secondary minerals of the country rock. It also occurs in association with acicular cuprite on old-time specimens.

Halite NaCl

Halite has been reported as cubes inside fluid inclusions in quartz by Intiomale and Oosterbosch (1974).

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

Hematite is a component of the country rock. Devos et al. (1974) report corrosion of hematite by chalcopyrite in ore of the Cu-I phase.

Hemimorphite [Zn.sub.4][Si.sub.2][O.sub.7][(OH).sub.2][center dot][H.sub.2]O

Buttgenbach (1947) reported the occurrence of hemimorphite at Kipushi as early as 1923, in crystals reaching 1 cm or more in fan-shaped groups. The prisms are generally sharp, transparent, translucent or opaque, typically flattened, vertically striated on {010} and terminated by {001} and {101}. The latter faces are sometimes curved and are often variably (yet symmetrically) developed, giving a nearly triangular termination. The author also describes the heteropolar (opposite) extremity exhibiting another combination of forms. The rare twinning on (001) reported by Levy in 1843 from Moresnet, Belgium (Goldschmidt, 1913, and others), was not observed by Buttgenbach (1947) from Kipushi or Moresnet.

Hemimorphite crystals occur as the most widespread secondary mineral throughout the deposit and the neighboring country rock of the footwall. Specimens are plentiful in collections, presenting a good opportunity to examine their morphology. Sometimes, poorly shaped crystals present a lamellar structure with multi-grooved faces seemingly due to the juxtaposition of parallel individuals.

Hemimorphite crystals are most commonly white (when opaque) or colorless (when transparent), rarely also a transparent blue of the most appreciated variety. Coloring by aurichalcite or pseudomalachite inclusions makes crystals opaque, blue or green; crystals may also be colored yellow by (supposedly) zincite, black by sulfides (chalcocite) or red by iron oxides. Associations most often include aurichalcite and less often pseudomalachite.

The habit of hemimorphite crystals is not easy to discern. The lower termination, always implanted on matrix, is extremely rare. Crystals are clustered either as spherically divergent groups, as "paddle-wheels" (in sub-parallel planes), or as spherical aggregates or crisscrossed in druses, superposition being a severe hindrance to accurate observation.

The upper termination is variably shaped depending upon truncations, and it is not always possible to identify any of the visible faces. Re-entrant angles can occur in place of the pedion, and the {101} faces can sometimes be unequally developed, probably due to growth along parallel axes of two or more individuals.

Hydrozincite [Zn.sub.5][(C[O.sub.3]).sub.2][(OH).sub.6]

Hydrozincite occurs as earthy or microcrystalline coatings in cavities in smithsonite and as acicular material intermixed with aurichalcite.

Kipushite [([Cu.sub.2+], Zn).sub.5]Zn[(P[O.sub.4]).sub.2][(OH).sub.6] [multiplied by] [H.sub.2]O

It is probably useful to recall that the original "kipushite" of Buttgenbach is different from the "kipushite" characterized later and currently accepted. In the early 1970's, the amateur who found the original material, later named "kipushite," on level 8m in the pillar, was actually searching for veszelyite, the famous old-time occurrence that every collector was then dreaming of finding. He found something blue, and was doubly successful because some crusts of microcrystalline veszelyite were indeed pan of the assemblage recovered (personal communication of Dr. Defern of Geneva), though the overall blue color was mainly due to pseudomalachite. A fair number of pieces became available on the Belgian collector market, labeled "veszelyite." A thorough re-examination of the specimens subsequently revealed small, prismatic, emerald-green crystals of a new species, which was named "kipushite" by Piret et al. (1985). Since Buttgenbach's earlier "kipushite" had been discredited as identical with veszelyite (Zsivny, 1932), the name was free to be used for another well-characterized species, and the authors chose to propose it in order to immortalize in the mineral literature the name of a famous deposit. The original discoverer (who had in the meantime retired) collaborated with others researching the precise location of the find, and in 1988 and 1989 the remainder of the original kipushite pocket was emptied, and an appreciable new lot of specimens was recovered.

Crystals of kipushite are emerald-green with a pale blue streak, transparent to translucent, with a vitreous luster, and appear as isolated prisms, as slightly diverging aggregates, as radiating clusters to 5 mm, and as rosettes to 7 mm. The most common habit observed by Piret et al. (1985) from the original find is prisms {111} elongate along [Mathematical Expression Omitted] and terminated principally by {100}; individuals reach 1 to 2 mm and exceptionally 5 mm. (Another termination is visible in the SEM photograph shown here; the crystals are from the second lot collected.)

Judging from the original description and from observations of later-recovered specimens, the associations include pseudomalachite (as blue or green nodules), some malachite, hemimorphite, white prisms of pyromorphite, ultramarine-blue microcrystalline masses of veszelyite, yellow and olive-green crusts of vauquelinite, libethenite (as acicular clusters, as small nodules with a radiating internal structure and also as equant to short prismatic crystals to 3 mm isolated on matrix), green pseudomorphs of reichenbachite after kipushite, quartz, and iron oxides.

Kipushite is isostructural with philipsburgite. As with veszelyite, the Cu:Zn ratio is variable due to a complex structure composed of alternating sheets which are different in each species (Piret et al., 1985).

Libethenite [Mathematical Expression Omitted]

Libethenite from Kipushi, for many years listed only in unpublished reports, was described for the first time in the literature as part of the kipushite assemblage (Piret et al., 1985), as acicular clusters. Crystals in the second lot of specimens from the pocket are gray-green or bluish with gray-whitish extremities due to incipient alteration, while the nodules are olive-green in color.

More material will probably come out when operations at depth have ceased and more intensive recovery in upper levels is attempted. The recovery of more good unaltered crystals would be of great interest in clarifying the mystery of the zincian variety of libethenite, to which three papers have already been devoted: The first one (the probable source of the confusion) is Mennell's historical paper of 1920: "Rare zinc-copper minerals from the Rhodesian Broken Hill mine . . . ." Mennell's principal "rare minerals" were undetermined grayish copper phosphates which could not be collected free from parahopeite admixture (copper is very scarce in Broken Hill ore, and therefore greenish and bluish traces stand out). Much less abundant was the well-crystallized ultramarine-blue zinc-copper phosphate which was not positively identified as veszelyite. Guillemin (1956) published an extensive review of copper phosphates, during the preparation of which he had produced many syntheses and so obtained a zincian libethenite, with an X-ray powder pattern "different from that of normal libethenite." Guillemin had performed an X-ray diffraction analysis of the specimen from Broken Hill in the collections of the Ecole des Mines (labeled veszelyite) and found the pattern "identical to that of synthetical zincian libethenite." In 1980 Notebaart and Korowski reported the discovery at Broken Hill of greenish blue globules (smaller than 2 mm) and encrustations in tarbuttite ore. This material yielded a powder diffraction pattern "identical to that of normal libethenite, but microchemical tests indicate the presence of both zinc and copper." So the problem remains unresolved until better specimens can be recovered for research.

Malachite [Mathematical Expression Omitted]

Malachite has only been reported from Kipushi since 1931, as minute crystals (Buttgenbach, 1947). It is also listed as a member of the kipushite assemblage (Piret et al., 1985), as pale earthy coatings. Occasionally, it is found as bunches of fibers to 5 mm and as crystals to 3 mm. Compact sprays of fibers to 7 cm were once recovered from depth. Crusts of mammillary malachite are found as a matrix for other secondary minerals like cerussite and pyromorphite, but the banded botryoidal malachite so common in the Shaba Crescent is not found at Kipushi.

Massicot PbO

Massicot appears as a yellow dusting widespread in fissures in the gangue, particularly near the cerussite turret.

Molybdenite Mo[S.sub.2]

This accessory species is remarkable because of its high rhenium content, up to 3% (Capitant et al., 1963). An incompletely characterized mineral containing at least 20% to 30% rhenium was reported by Capitant et al. (1963), and a pure rhenium sulfide has recently been described from Russia (see the "What's new in minerals?" report elsewhere in this issue).

Pseudomalachite [Mathematical Expression Omitted]

Pseudomalachite is quite abundant in the oxidation zone, and often underlies other secondary species. Banded crusts to 2 cm of a dark green to bluish green color are known. When found as translucent nodules, as in the kipushite assemblage, pseudomalachite appears either green or blue.

Pyrite Fe[S.sub.2]

Pyrite is one of the two earliest sulfides at Kipushi. Framboids (raspberry-like micro-aggregates) and simple crystal habits, commonly with slightly corroded faces, are common in the country rock, whereas in the ore, crystal remnants are scarcer than those of arsenopyrite. Good crystals seem to occur only in association with siderite, which played the role of a protective barrier against supergene alteration. A few specimens recently purchased in Tucson are composed of lustrous crystals to 1 cm with concave faces, their habit being the dominant octahedron slightly modified by the pyritohedron and the diploid. One side shows mainly supergene alteration and one side shows intact crystals, the transition lined by goethite needles which form domes (perpendicular to the needles) in some places. One curiosity consists of a combination of early and late modifications: a pyrite crystal wherein an aggregate of siderite crystals (developed probably as a recrystallization of the gangue mineral at the time of deposition of the primary sulfide) is covered by a dome of goethite. The sheaths of pyrite surrounding the sphalerite lenses are of a later generation (Ottenburghs, 1964).

Pyromorphite [Pb.sub.5][(P[O.sub.4]).sub.3]Cl

Pyromorphite has been known at Kipushi since 1924 (Buttgenbach, 1947). A vein of similar crystals was found by collectors during the mid-1970's in situ in the pillar; the crystals are straw-yellow, opaque with a resinous luster, and up to 7 mm long. They are positioned obliquely on a carpet of bluish pseudomalachite covering a layer of a black oxide (probably heterogenite), as isolated hexagonal prisms, terminated by {001} and modified by {101}. The faces are longitudinally striated, giving the appearance that each crystal is formed by a group of subparallel smaller prisms, not all reaching the extremities. Crystals thus appear much thicker in the middle, like a barrel. Some are aggregated in divergent groups without perfect spherolithic disposition. Larger, stubby, hexagonal dipyramids of the same color and truncated by {001} have been recovered from a block of goethite.

Quartz Si[O.sub.2]

Quartz is the third most common component of the country rock (20%), and probably constitutes the bulk of the gangue, as it was not replaced by sulfides like the carbonates were. Good specimens come from the preparatory workings, as zoned, clearly amethystine crystals associated with (zincian) dolomite. Crystals are doubly terminated and slightly twisted longitudinally, with a multiple second termination due to growth along parallel axes. Amethyst crystals from Kipushi are very distinctive.

Reichenbachite [Mathematical Expression Omitted]

The discovery of reichenbachite can be attributed to the perseverance of collectors in emptying the kipushite pocket. Kipushite crystals can occur pure, or only partially replaced, while others are complete pseudomorphs of reichenbachite after kipushite (M. Deliens, personal communication). Dull, opaque crystals commonly occur as rosettes to 7 mm on a carpet of pseudomalachite.

Renierite [(Cu, Zn).sub.11][(Ge, As).sub.2][Fe.sub.4][S.sub.16]

The occurrence of renierite was first observed by Thoreau (1928), who called it "orange bornite." In polished sections and cleavages, however, renierite is easily differentiated from bornite through the retention of its original (somewhat darker) bronze color. The description as a new species (Vaes, 1948) named it in honor of the Belgian geologist A. Renier. Eight analyses performed in the Central Laboratory of Likasi gave remarkably consistent results.

Renierite is widespread at Kipushi as small, round inclusions disseminated in primary bornite, and as massive bodies in two Ge-rich zones linked with the two boundaries of primary bornite. These are located in the upper levels, from 275 to 400, and in the lower levels from 725 to 775. From level 850 downwards, renierite inclusions become scarce and are completely absent under level 975, as is primary bornite. Renierite also occurs very sporadically in the traces of chalcopyrite and tennantite present in the iron-rich sphalerite pipes (Ottenburghs, 1964), although never in the sphalerite itself.

Germanium occurs as a trace element in many common sulfides (Intiomale and Oosterbosch, 1974). Deutzmann (1961) reported a secondary germanium ore mineral replacing renierite, which exhibits a yellow-olive tinge under the microscope.

Renierite from Kipushi is magnetic, making it easy to obtain a pure product for investigation, and facilitating industrial recovery from copper concentrates. The degree of magnetism is variable from one sample to the next, and is related to the crystal structure rather than the iron content.

Vaes (1948) described renierite as cubic. However, it is definitely tetragonal pseudoisometric, and is related to the sphalerite structure (Bernstein, 1986). Massive renierite contains abundant rugs lined with small crystals to 1.5 mm (Vaes, 1948). In our specimens, crystal faces appear like tiles of a roof when examined under the binocular microscope. SEM photographs are good for more precise visualization.

The exact formula of renierite remained in dispute for many years. Bernstein (1986) found that the mineral is a unique example of an extensive solid solution series between zincian and arsenian end-members, through the coupled substitution of [Zn.sup.2+] + [Ge.sup.4+] for [Cu.sup.1+] + [As.sup.5+] (each pair totaling a 6+ charge).

During the early 1970's, the demand for germanium was high on the international market. The rich zones were exploited, and ore was sent in barrels by plane to Europe after manual sorting according to the typical color of renierite, the richest Ge-containing sulfide (14%). Renierite accounted for 99% of the germanium production (Ottenburghs, 1964), totaling about 125 tons.

Siderite [Fe.sup.2+]C[O.sub.3]

Siderite appears regularly in unpublished systematic lists, though attractive, valuable crystals are not represented in collections. The recent recovery of the curious specimens of pyrite, siderite and goethite have filled this deficiency to some extent.

Silver Ag

Silver was deposited as a trace element in primary bornite and, to a lesser extent, in tennantite and betekhtinite (Intiomale and Oosterbosch, 1974). Silver occurs mostly as grayish stains on chalcocite masses, good specimens being rare. Yet some noteworthy old-time pieces are known, like those with specks of silver spread on an aggregate of blue hemimorphite on a matrix of massive aurichalcite, and also in brittle assemblages of metallic silver-white "oak leaves" with a skeletal framework.

Smithsonite ZnC[O.sub.3]

The occurrence of smithsonite at Kipushi is not mentioned in the literature before 1931, and is merely cited by Buttgenbach (1947) without any physical description. Crystals are indeed rare; the most spectacular occurrences are banded concretionary or stalactitic masses in the footwall cavities, which are suitable for lapidary work.

At level 100, the workings are cut by a roughly cylindrical offshoot about 60 cm in diameter consisting of a core of massive chalcocite surrounded by a sheath of smithsonite crystals. Otherwise, crystals have been found only sparingly in supergene pockets, in ore sometimes recovered from a block in the dumps. The crystals, reaching to 3 mm, are opaque or rarely translucent, and mostly grayish or beige; they become attractive when colored green or blue. The crystal habit resembles rice grains with visible longitudinal striations reflecting the underlying rhombohedral structure. Sometimes external growths of rhombs form pleasing figures delineating stages of the crystal growth or, with enough imagination, Hauy's solid.

Sphalerite (Zn, Fe)S

Sphalerite (which constitutes 50% of the ore) is nearly always massive with a cubic cleavage; the banded variety is very rare, as are significant crystals. An isolated, poorly shaped old-time crystal 10 cm long was once seen; crystals to 2 cm of the green variety on a dolomitic matrix have also been found.

Sphalerite belongs to two paragenetic sequences (Deutzmann, 1961), an iron-rich assemblage well-represented in the appendicular pipes, and a later-deposited iron-poor variety which is richer in trace elements like Cd and Co. The average content of Cd is 0.05%, and the content of Co is variable, from 20 to 820 ppm (Intiomale and Oosterbosch, 1974). The color of the iron-poor sphalerite varies from colorless to yellow to pale brown. A typical occurrence at Kipushi is the green variety (supposed to be copper-rich). It does indeed contain some copper (Intiomale and Oosterbosch, 1974), and also cobalt. Hoffman and Henn (1984) found that the green color is, in fact, due to trace cobalt in the amount of about 840 ppm. Fritsch and Rossman (1987) have since confirmed that the green color of sphalerite is due to cobalt.

Stromeyerite AgCuS

Stromeyerite is the sole silver sulfide at Kipushi, and seems always to be secondary (Deutzmann, 1961; Devos et al., 1974).

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

Tennantite, reported by Thoreau (1928) as "tetrahedrite," is widespread in most types of ore as gray-whitish masses or veins with a metallic luster. Umba et al. (1977) reported crystals to 1 cm, and showed a photograph of a specimen from the Mineralogical Museum of the geological staff in Likasi. The official formula of tennantite was changed recently through the addition of Ag (Fleischer and Mandarino, 1995), which is interesting to correlate with the presence of silver as a trace element reported by Intiomale and Oosterbosch (1974).

Tsumebite [Pb.sub.2]Cu(P[O.sub.4])(S[O.sub.4])(OH)

Tsumebite is probably not as rare at Tsumeb as initially thought (Pinch and Wilson, 1977). Yet phosphates are scarce in Tsumeb, represented mostly by the rare tsumebite and some pyromorphite (Guillemin, 1956). In contrast, phosphates are quite abundant at Kipushi, where tsumebite has been recognized on a single specimen in the Tervuren Museum (M. Deliens, personal communication). During the 1960's and 1970's (and even the 1980's), collectors in Katanga were accustomed to searching for relatively large specimens and were not inclined to save such tiny crystallizations, especially among so many greenish occurrences. Tsumebite therefore, probably occurs more commonly than supposed in Kipushi too.

Tungstenite W[S.sub.2]

Tungstenite was reported by Moh (1973) in ore from level 280, as oriented lamellae in chalcocite, with minor renierite. Devos et al. (1974) report that tungstenite lamellae are always present near germanite, having probably been deposited when renierite replaced germanite, considering that renierite does not accept W in its structure as germanite does.

Turquoise [Cu.sup.2+][Al.sub.6][(P[O.sub.4]).sub.4][(OH).sub.8][multiplied by][H.sub.2]O

An extensive occurrence of turquoise is reported by Intiomale and Oosterbosch (1974) in the overburden covering the Kakontwe.

Vauquelinite [Pb.sub.2][Cu.sup.2+](Cr[O.sub.4])(P[O.sub.4])(OH)

In addition to its type locality in the Urals, vauquelinite has also been reported from a fair number of other localities, among which is Musonoi in the western Kolwezi klippe. In specimens from Kipushi the canary-yellow color is striking, and even misleading if taken as analogous to uranium occurrences in Luiswishi and in Shinkolobwe (Gauthier et al., 1989). Autunite is erroneously quoted in early internal reports; but in fact there is no radioactivity at all in the primary ore. Even the pioneer collectors had specimens confiscated from their cases and disallowed at the official control checks before delivery of exportation permits, on the assumption they were radioactive.

The earliest report of yellow vauquelinite from Kipushi is in the kipushite assemblage (Piret et al., 1985). On the specimens of pyromorphite from the pillar, tiny, opaque, canary-yellow plates, generally isolated and lying flat between the layers of pseudomalachite and black oxides, are present rather abundantly. Sometimes the tiny plates appear assembled as clusters resembling a rose.

Old-time specimens in collections consist of rough yellow clods to 2 mm and yellowish plates to 3 mm of vauquelinite pseudomorphs, probably after cerussite, scattered on a matrix of mammillary chrysocolla, with fibrous malachite complementing the association. The yellow mineral has been identified as vauquelinite on both the recently collected and the old-time specimens (courtesy of Zelimir Gabelica of Namur, Belgium).

Veszelyite [(Cu.sup.2+], Zn).sub.3](P[O.sub.4])[(OH).sub.3][multiplied by]2[H.sub.2]O

Kipushi is one of the historical localities for the occurrence of veszelyite, a mineral name with an amusing history. The type-material was described from a locality in Transylvania in two papers of 1874 and 1880 (quoted in Zsivny, 1932), with an inaccurate As content of about 10% and a greenish blue tinge (supposedly due to the presence of As). Some 50 years later, two additional descriptions were published by Mennell (1920) and by Japanese authors in 1922 (quoted in Zsivny, 1932). Mennell (1920) described an ultramarine-blue well-crystallized mineral of which only about 1 gram was collected. The author considered that it could be veszelyite, yet the crystal habit was quite particular, with a large (typical) "orthopinacoid" {100} which had not been observed in the original veszelyite. Above all, the new mineral contained no As. The Japanese authors described "arakawaite," which they soon considered identical with "Broken Hill's veszelyite," considering that both contained no As (quoted in Zsivny, 1932) and were blue.

Buttgenbach (1947) then described "kipushite" in 1926. The occurrence at level 100 was first reached by exploratory workings and later (in 1932) by an exploitation tunnel. According to legend, crystals abundantly covered the walls in a large area, representing the largest find of the best crystals then known. These were very sharp, from 3 to 7 mm in size (and in rare cases up to 1 cm), opaque and of a deep blue color with azure-blue translucent areas.

The name "kipushite" was a working name chosen to please executives of the U.M.H.K. who had suggested it. Buttgenbach retained the working name, probably for too long, yet not without reason. He had identified immediately "his mineral" with the ultra-marine-blue "unnamed" species of Mennell, which he also called "kipushite," and stated that it was probably identical with "arakawaite" if it could be ascertained that the latter contained no As at all; all of these minerals (including veszelyite) would be members of an isomorphous series. Recognition of the morphological identity of the varieties with veszelyite must be credited to Buttgenbach.

Zsivny (1932) carefully reinvestigated the type-material (morphologically, optically and chemically), and compared his results with data from the literature concerning the varieties. He proposed discreditation of "kipushite" because the type material contained no As, the name veszelyite having chronological priority.

Finally, Guillemin (1956) discovered that veszelyite from Broken Hill was actually a zincian libethenite. Generally veszelyite crystals are short and prismatic (with the recent exception of the incredible crystals from the Black Pine mine, Montana; Waisman, 1992). From Kipushi, the habit is pseudo-octahedral, composed of a combination of the forms {110} and {011}. Moreover, Kipushi crystals typically show a complete absence of the pinacoid {100} and the presence of an often well-developed "belt-like" truncation indexed as {121} according to international standards of crystal positioning (Zsivny, 1932). It is positioned similar to [Mathematical Expression Omitted] and [Mathematical Expression Omitted], which had been observed rarely by Zsivny as small single faces. Yet Buttgenbach retained his handsome vertical orientation in order to better show the typical truncation, and probably also because he could not easily accept that his "kipushite" was not a new species.

Associations include mostly blue hemimorphite and accessorily aurichalcite with some chrysocolla. Otherwise, veszelyite occurs sparingly; it has been reported as pan of the kipushite assemblage, and as poorly shaped small crystals on an old-time specimen with massive aurichalcite and hemimorphite.

Chemically, veszelyite is remarkable because of its variable Cu:Zn ratio, a feature related to its structure consisting of two kinds of sheets (Piret et al., 1985).

Willemite [Zn.sub.2]Si[O.sub.4]

Willemite is rare and was not observed at Kipushi by early investigators. Umba et al. (1977) report short, whitish yellow hexagonal prisms to 1 mm, terminated with a {334} rhombohedron face. One old-time specimen consists of a dark sphalerite crystal group partially covered by aggregates of small, pale brown, poorly shaped willemite crystals.

Wurtzite (Zn, Fe)S

An occurrence of sphalerite-after-wurtzite pseudomorphs was reported by Deutzmann (1961).

Zincite (Zn, [Mn.sup.2+])O

In the oxidation zone, zincite is widespread as brownish yellow earthy fillings. A more limited occurrence is as reddish mammillary crusts underlying aurichalcite in some specimens. One good old-time specimen consists of very brittle, micaceous, transparent plates of a dark red color, with hexagonal terminations, on a matrix of green sphalerite and chalcocite.

ACKNOWLEDGMENTS

I am grateful to Gilbert Gauthier for his ever-enthusiastic support, to Dr. Wendell Wilson who inspired me with the self-confidence necessary for starting preparation of this article, to Dr. Armand Francois who supplied the geological information and critically reviewed that section, to Dr. Michel Deliens for the critical reading of the mineral section, and to Dr. Roger Warin, President of the Association des Geologues Amateurs de Belgique in Liege, Belgium, for many fruitful discussions. Dr. Raoul Ottenburghs of Leuven, Belgium, kindly supplied unpublished references. Dan Behnke was kind enough to answer the questions of a beginner about aspects of mineral photography. Dr. Bruce Cairncross of Johannesburg, South Africa, was prompt in supplying Hughes' (1979) reference.

REFERENCES

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MOH, G. H. (1973) Das Cu-W-S-System und seine Mineralien sowie ein neues Tungstenitvorkommen in Kipushi/Katanga. Mineralium Deposita, Springer Verlag, Berlin, 8, 291-300.

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STRUNZ, H., GEIER, B. H., and SEELIGER, E. (1958) Gallit, CuGa[S.sub.2], das erste selbstandige Galliummineral und seine verbreitung in den Erzen der Tsumeb- und Kipushi-Mine. Neues Jahrbuch fur Mineralogie Monatshefte, 1958a, 241-264.

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RELATED ARTICLE: Table 1. Minerals reported from the Kipushi mine. (Species for which Kipushi is the type locality are given in bold.)

Elements

Bismuth Bi Copper Cu Graphite C Silver Ag

Sulfides & Sulfosalts

Aikinite PbCuBi[S.sub.3] Arsenopyrite FeAsS Betekhtinite [Cu.sub.10](Fe, Pb)[S.sub.6] Bismuthinite [Bi.sub.2][S.sub.3] Bornite [Cu.sub.5]Fe[S.sub.4] Briartite [Cu.sub.2](Fe, Zn)Ge[S.sub.4] Carrollite Cu[(Co, Ni).sub.2][S.sub.4] Chalcocite [Cu.sub.2]S Chalcopyrite CuFe[S.sub.2] Cobaltite CoAsS Cosalite [Pb.sub.2][Bi.sub.2][S.sub.5] Covellite CuS Digenite [Cu.sub.9][S.sub.5] Emplectite CuBi[S.sub.2] Enargite [Cu.sub.3]As[S.sub.4] Galena PbS Gallite CuGa[S.sub.2] Germanite [Cu.sub.26][Fe.sub.4][Ge.sub.4][S.sub.32] Idaite [Cu.sub.3]Fe[S.sub.4] (?) Linnaeite [Mathematical Expression Omitted] Marcasite Fe[S.sub.2] Mawsonite [Mathematical Expression Omitted] Molybdenite Mo[S.sub.2] Pyrite Fe[S.sub.2] Pyrrhotite [Fe.sub.1 - x]S Renierite [(Cu, Zn).sub.11][(Ge, As).sub.2][Fe.sub.4][S.sub.16] Sphalerite (Zn, Fe)S Stannite [Cu.sub.2]FeSn[S.sub.4] Stromeyerite AgCuS Sulvanite [Cu.sub.3]V[S.sub.4] Tennantite [(Cu, Ag, Fe, Zn).sub.12][As.sub.4][S.sub.13] Tetradymite [Bi.sub.2][Te.sub.2]S Tetrahedrite [(Cu, Fe).sub.12][Sb.sub.4][S.sub.13] Tungstenite W[S.sub.2] Valleriite 4(Fe, Cu)S[multiplied by]3(Mg, Al)[(OH).sub.2] Wittichenite [Cu.sub.3]Bi[S.sub.3] Wurtzite (Zn, Fe)S

Chlorides

Atacamite [Mathematical Expression Omitted]

Fluorides

Fluorapatite [Ca.sub.5][(P[O.sub.4]).sub.3]F Fluorite Ca[F.sub.2]

Oxides

Cuprite [Cu.sub.2]O Goethite [Alpha]FeO(OH) Hematite [Alpha][Fe.sub.2][O.sub.3] Heterogenite [Co.sup.3+]O(OH) Magnetite [Mathematical Expression Omitted] Massicot PbO Pyrolusite [Mn.sup.4+][O.sub.2] Tenorite CuO Zincite (Zn, [Mn.sup.2+])O

Carbonates

Aurichalcite [(Zn, [Cu.sup.2+]).sub.5][(C[O.sub.3]).sub.2][(OH).sub.6] Azurite [Mathematical Expression Omitted] Bismutite [Bi.sub.2](C[O.sub.3])[O.sub.2] Calcite CaC[O.sub.3] Cerussite PbC[O.sub.3] Dolomite CaMg[(C[O.sub.3]).sub.2] Hydrozincite [Zn.sub.5][(C[O.sub.3]).sub.2][(OH).sub.6] Malachite [Mathematical Expression Omitted] Rosasite [(Cu.sup.2+], Zn).sub.2](C[O.sub.3])[(OH).sub.2] Siderite [Fe.sup.2+]C[O.sub.3] Smithsonite ZnC[O.sub.3]

Silicates

Actinolite-tremolite [Ca.sub.2][(Mg, [Fe.sup.2+]).sub.5][Si.sub.8][O.sub.22][(OH).sub.2] Albite NaAl[Si.sub.3][O.sub.8] Chrysocolla [([Cu.sup.2+], Al).sub.2][H.sub.2][Si.sub.2][O.sub.5][(OH).sub.4][multiplied by]n[H.sub.2]O Clinochlore [(Mg, [Fe.sup.2+]).sub.5]Al([Si.sub.3]Al)[O.sub.10][(OH).sub.8] Hemimorphite [Zn.sub.4][Si.sub.2][O.sub.7][(OH).sub.2][multiplied by][H.sub.2]O Muscovite K[Al.sub.2](SiAl)[O.sub.10][(OH, F).sub.2] Palygorskite [(Mg, Al).sub.2][Si.sub.4][O.sub.10](OH)[multiplied by]4[H.sub.2]O Phlogopite K[Mg.sub.3][Si.sub.3][Al.sub.10][(F, OH).sub.2] Quartz Si[O.sub.2] Riebeckite [Mathematical Expression Omitted] Talc [Mg.sub.3][Si.sub.4][O.sub.10][(OH).sub.2] Willemite [Zn.sub.2]Si[O.sub.4]

Phosphates

Fluorapatite [Ca.sub.5][(P[O.sub.4]).sub.3]F Kipushite [([Cu.sup.2+], Zn).sub.5]Zn[(P[O.sub.4]).sub.2][(OH).sub.6][multiplied by][H.sub.2]O Libethenite [Mathematical Expression Omitted] Pseudomalachite [Mathematical Expression Omitted] Pyromorphite [Pb.sub.5][(P[O.sub.4]).sub.3]Cl Reichenbachite [Mathematical Expression Omitted] Tsumebite [Pb.sub.2]Cu(P[O.sub.4])(S[O.sub.4])(OH) Turquoise [Cu.sup.2+][Al.sub.6][(P[O.sub.4]).sub.4][(OH).sub.8][multiplied by]4[H.sub.2]O Vauquelinite [Pb.sub.2][Cu.sup.2+](Cr[O.sub.4])(P[O.sub.4])(OH) Veszelyite [([Cu.sup.2+], Zn).sub.3](P[O.sub.4])[(OH).sub.3][multiplied by]2[H.sub.2]O Vivianite [Mathematical Expression Omitted]

Arsenates

Adamite [Zn.sub.2](As[O.sub.4])(OH) Beudantite [Mathematical Expression Omitted] Conichalcite Ca[Cu.sup.2+](As[O.sub.4])(OH)

Vanadates

Descloizite PbZn(V[O.sub.4])(OH) Vanadinite [Pb.sub.5][(V[O.sub.4]).sub.3]Cl

Tungstates

Scheelite CaW[O.sub.4]

Sulfates

Anglesite PbS[O.sub.4] Barite BaS[O.sub.4] Beaverite Pb[([Cu.sup.2+], [Fe.sup.3+], Al).sub.3][(S[O.sub.4]).sub.2][(OH).sub.6] Beudantite [Mathematical Expression Omitted] Brochantite [Mathematical Expression Omitted] Devilline [Mathematical Expression Omitted] Goslarite ZnS[O.sub.4][multiplied by]7[H.sub.2]O Gypsum CaS[O.sub.4][multiplied by]2[H.sub.2]O Tsumebite [Pb.sub.2]Cu(P[O.sub.4])(S[O.sub.4])(OH)

Chromates

Vauquelinite [Pb.sub.2][Cu.sup.2+](Cr[O.sub.4])(P[O.sub.4])(OH)

Molybdates

Wulfenite PbMo[O.sub.4]
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Date:May 1, 1995
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