Printer Friendly

The Palitra pegmatite: a newly discovered hyperalkaline pegmatite in the Lovozero massif, Kola Peninsula, Russia.

The Palitra pegmatite, recently discovered during underground mining operations at a loparite deposit in the Lovozero massif, is one of the most interesting mineral localities within this famous alkaline complex. It has produced remarkable specimens of many rare minerals, including the world's best specimens of natrosilite and manaksite, and is the type locality for bario-olgite, kapustinite, pautovite and potassicarfvedsonite.

INTRODUCTION

The Palitra pegmatite, located on the northern flank of Kedykverpakhk Mountain in the Lovozero Mountains on the Kola Peninsula, is the largest known "dry" hyperagpaitic pegmatite in the Lovozero massif. Late-stage hydrothermal activity did not develop here (hence the term "dry"), and consequently remarkably fresh anhydrous and water-poor ultra-alkaline minerals rarely found or preserved elsewhere occur in the pegmatite.

Dry hyperagpaitic pegmatites are not rare in the deep levels of the Lovozero intrusion, having been encountered in underground mines at Mt. Karnasurt, Mt. Kedykverpakhk and Mt. Alluaiv. However, they are typically thin veins and lenses, usually not thicker than 5 cm (Khomyakov, 1995; Pekov, 2000). All famous Lovozero pegmatites, including pegmatites found at significant depths from the surface such as the Yubileinaya, the Shkatulka, and the Shomiokitovoye pegmatites, were altered by hydrothermal processes. Late-stage water-bearing minerals which have completely or partially replaced primary minerals are abundant in these pegmatites (Pekov, 2000). Although the existence of larger (up to 1 meter thick), only slightly altered dry pegmatites has been mentioned in earlier studies of the Lovozero massif (Khomyakov et al., 1980), these pegmatite bodies were unstable when exposed to water, were never described in detail, and unfortunately no longer exist for comparison.

Therefore, it is both interesting and important to describe in detail a large, dry, differentiated hyperalkaline pegmatite, especially inasmuch as the Palitra pegmatite differs significantly from smaller pegmatites in its mineralogy. The author was fortunate to have been able to examine the Palitra pegmatite only a few days after its discovery, well before the moisture and dust of an operating mine had had time to exert their destructive influences on the typically unstable hyperalkaline minerals which form almost half of the polymineralic core of the pegmatite. Unique fresh material was collected immediately, permitting preservation of the many uncommon assemblages; subsequently, the minerals were studied intensively in the laboratory using chemical, optical and structural techniques.

In the course of this study we have found 46 mineral species in the Palitra pegmatite, including four new species accepted by the IMA Commission on New Minerals and Mineral Names: bario-olgite (IMA No. 2003-002), kapustinite (2003-018), potassicarfvedsonite (2003-043), and pautovite (2004-005) (Pekov et al., 2003b; 2004a,b; 2005). The world's largest masses and finest specimens of natrosilite (semitransparent single-crystal blocks up to 20 X 30 cm) and manaksite (crystals to 8 X 20 cm, some perfectly formed!) have been found in the Palitra pegmatite. Just as noteworthy are the pegmatite's remarkable, well-formed crystals of thorosteenstrupine (the first ever found), kazakovite, chkalovite, vuonnemite, nalipoite, revdite, minerals of the nordite-(Ce)/ferronordite-(Ce) series, very large segregations of zakharovite, villiaumite, plates of lomonosovite, the rare sulfides bartonite and chlorbartonite, and water-clear, gem-quality nepheline.

[FIGURE 1 OMITTED]

[FIGURE 2 OMITTED]

HISTORY

The Palitra pegmatite was discovered on August 20, 2002 by Pavel Rayanov, a miner, during construction of an inclined underground shaft in the Kedykverpakhk area of the Karnasurt mine. On the following day, Nickolay Pavlov, chief geologist of the mine, and geologist Ludmila Ksenofontova examined the pegmatite and noted the wonderful diversity of its minerals. For further study, they kindly invited the author and local amateur mineralogist Viktor Grishin to see the amazing assemblages that had been uncovered. Grishin proposed a fitting name for the pegmatite: the Palitra (in English, "palette"), in allusion to the large pods of brightly colored minerals (red villiaumite, pearly-white natrosilite, green aegirine, lilac ussingite, lemon-yellow vuonnemite, crimson sodalite, orange eudialyte, salmon-pink serandite, dark-brown lomonosovite and lorenzenite, etc.) that had been exposed.

GEOLOGICAL SETTING, MORPHOLOGY AND STRUCTURE

The Palitra pegmatite is situated within complex, layered urtite-foyaite-lujavrite rocks. Only the upper part and core of the pegmatite has been uncovered, the lower part remaining inaccessible to observation. Overall the Palitra pegmatite is probably lensshaped, with a length of 7 meters and a thickness of more than 1.5 meters. The upper contact surface is inclined, dipping eastward.

The exposed portion of the Palitra is enclosed by foyaite. A layer of loparite-enriched malignite 10 cm thick lies above the pegmatite. In some areas, the foyaite is enriched by sodalite and villiaumite lenses up to 20 cm thick; these lenses lie between the pegmatite and the malignite layer. All contacts of the pegmatite with surrounding rocks are sharp. The Palitra pegmatite body has clear zoning in its upper part whereas its core is characterized by a "spotted" texture because of the chaotic distribution of areas of differing mineralization.

Immediately below the upper contact line, a nepheline zone 5 to 12 cm thick is developed in the pegmatite. Elongated nepheline crystals pointing downward form brush-like crusts, with eudialyte grains and dark green aegirine aggregates between the nepheline crystals.

Just under the nepheline zone is a eudialyte-aegirine-microcline zone. Its most striking feature is the abundance of fibrous green aegirine spheroids and hemispheres up to 30 cm in diameter. Also, this zone contains large blocks of microcline (up to 15 X 60 cm) and eudialyte (up to 6 X 20 cm) and long prisms of arfvedsonite (up to 5 mm X 15 cm). Aggregates of smaller individual crystals of microcline, aegirine, eudialyte, nepheline, sodalite, lorenzenite, lamprophyllite, etc., fill the interstices. Microcline blocks contain abundant inclusions of bright-red villiaumite. The eudialyte-aegirine-microcline zone is seen to extend into the bottom of the mine workings (i.e. its thickness is more than 1.5 meters), and it constitutes more than two-thirds of the exposed portion of the pegmatite.

Numerous pods of hyperalkaline minerals are found within this zone. The largest pods (more than 70 X 100 cm) occur in the central portion of the pegmatite body and can be considered its core. The major constituents of the pods are sodalite, analcime, ussingite, villiaumite and natrosilite, in variable ratios. Sporadically, lomonosovite, manaksite and natrolite become rock-forming minerals. Black aegirine, vuonnemite, serandite, sphalerite, steenstrupine-(Ce) and kapustinite are present in subordinate quantities, accompanied by accessory amounts of nordite-(Ce), ferronordite-(Ce), vitusite-(Ce), phosinaite-(Ce), kazakovite, barytolamprophyllite, mangan-neptunite, chkalovite, thorosteenstrupine, bario-olgite, nalipoite and lollingite. Rarely, small cavities contain revdite.

[FIGURE 3 OMITTED]

[FIGURE 4 OMITTED]

[FIGURE 5 OMITTED]

[FIGURE 6 OMITTED]

[FIGURE 7 OMITTED]

MINERALS

Aegirine NaFe[Si.sub.2][O.sub.6]

Aegirine, an important rock-forming mineral in the Palitra pegmatite, is widespread in all zones and assemblages. Several aggregate habits differing in morphology and color have been found. Aegirine occurs most abundantly as green acicular crystals and fibers, forming spheres and hemispheres up to 30 cm in diameter, and also chaotic masses of crystalline aggregates. In most cases the aegirine spheres contain lomonosovite, lorenzenite or eudialyte in their centers. The largest aegirine crystals measure 1 mm X 15 cm. Black prismatic aegirine is a typical component of late polymineralic pods. An unusual variety of aegirine has been found as pseudomorphs after manaksite, associated with serandite; here it forms lath-like crystals up to 5 mm long, commonly split and curved. The crystals are color-zoned: orange-red to bright red in the middle sections, pale blue-green on the terminations, and yellow in intermediate parts. Some crystals have yellow-orange cores and olive-green terminations. It has been proposed, but not confirmed, that the red aegirine in the pseudomorphs after manaksite might be Mn-enriched; electron probe microanalyses indicate a common aegirine composition with MnO [less than or equal to] 1.7 weight %. Black late-stage aegirine contains 3 weight % Ti[O.sub.2].

Analcime NaAl[Si.sub.2][O.sub.6] * [H.sub.2]O

Analcime is widespread in the polymineralic core of the Palitra pegmatite. Massive, coarse-grained analcime aggregates up to 7 cm and sodalite-ussingite-analcime intergrowths have been observed. Sharp, gray to white, trapezohedral analcime crystals up to 4 cm are included in dark red villiaumite, associated with serandite and vuonnemite. The walls of cavities filled by villiaumite are lined by analcime crystals which may be partially or completely replaced by ussingite.

Arfvedsonite [Na.sub.3]([Fe.sup.2+], Mg)[.sub.4][Fe.sup.3+][Si.sub.8][O.sub.22](OH)[.sub.2]

Arfvedsonite is a typical mineral of the eudialyte-aegirine-microcline zone. It occurs as black, poorly terminated, elongated prismatic crystals up to 5 mm X 15 cm, bounded by the faces {110} and {010}. Arfvedsonite "suns" up to 20 cm in diameter are not uncommon. The average chemical composition of arfvedsonite corresponds to the following formula: ([Na.sub.0.62][K.sub.0.32])[.sub.[SIGMA]0.94]([Na.sub.1.92][Ca.sub.0.08])[.sub.[SIGMA]2]([Fe.sub.2.13.sup.2+][Mg.sub.1.55][Fe.sub.0.80.sup.3+][Mn.sub.0.26][Ti.sub.0.26])[.sub.[SIGMA]5]([Si.sub.7.66][Al.sub.0.29][Fe.sub.0.05.sup.3+])[.sub.[SIGMA]8][O.sub.22](OH)[.sub.1.97][Cl.sub.0.03].

Bario-olgite Ba(Na,Sr,REE)[.sub.2]Na[P[O.sub.4]][.sub.2]

Bario-olgite, the barium analog of olgite, is a new mineral recently described from the Palitra pegmatite (Pekov et al., 2004a). It occurs as equant, flattened grains to 1.5 cm, some showing a hexagonal cross section. Several well-formed prismatic crystals of bario-olgite up to 3 mm long were found by V. G. Grishin in a villiaumite cavity; the crystals show faces {100}, {100}, {101}, {101}, {101} and {101}, as well as other faces visually similar to those found on quartz crystals. Unequally developed faces of four different pyramids illustrate the primitive symmetry. Bario-olgite is transparent and pale green, with vitreous luster and imperfect cleavage. It fluoresces strongly pinkish orange in shortwave ultraviolet light and very weakly pinkish red in longwave ultraviolet light. Bario-olgite occurs in a manaksite-villiaumite-natrosilite assemblage; it commonly forms inclusions in manaksite and is found between manaksite and natrosilite, villiaumite, aegirine, vuonnemite, or chkalovite (Pekov et al., 2004a).

[FIGURE 8 OMITTED]

Bartonite [K.sub.6][Fe.sub.24][S.sub.27]

Bartonite has been found in the Palitra pegmatite, and (for the second time in Lovozero) in an ussingite-natrolite vein in the same Mt. Kedykverpakhk deposit (Pekov et al., 2003a). Together with the visually indistinguishable chlorbartonite, it forms dark bronze-brown, granular masses (to 1 cm) with metallic luster. Both species were found in the upper part of the Palitra pegmatite body, associated with nepheline, eudialyte, lorenzenite, arfvedsonite, aegirine and villiaumite.

Barytolamprophyllite [Na.sub.2](Ba,Sr)[.sub.2](Ti,Mn,Fe)[.sub.3](Si[O.sub.4])[.sub.4](OH,F)[.sub.2]

An Mn-enriched barytolamprophyllite is a rare late-stage mineral in the pegmatite. It forms golden yellow rosettes and spheroids up to 7 mm in diameter, consisting of radiating acicular crystals. It also occurs as golden brown, transparent, elongated lamellae to 4 mm overgrown epitactically on lorenzenite.

Belovite-(Ce) [Sr.sub.3]NaCe(P[O.sub.4])[.sub.3](F,OH)

Belovite-(Ce) occurs as colorless acicular to hairlike crystals up to 3 mm long with hexagonal cross-sections. The crystals form cotton-like aggregates intergrown in villiaumite and perched on microcline and aegirine.

Bornemanite [Na.sub.4]Ba[Ti.sub.2]Nb[Si.sub.4][O.sub.17](F,OH) * [Na.sub.3]P[O.sub.4]

Bornemanite was found in a late-stage assemblage. It forms pale yellow to lemon-yellow spheroids to 2 mm in diameter, consisting of transparent, elongated lamellar crystals with pearly luster. It commonly forms overgrowths on lomonosovite and in some cases replaces it. Occasionally, bornemanite spheroids and rounded aggregates (to 1 cm) of curved scales are found intergrown in villiaumite and natrosilite.

[FIGURE 9 OMITTED]

[FIGURE 10 OMITTED]

Chkalovite [Na.sub.2]Be[Si.sub.2][O.sub.6]

Chkalovite occurs in the core of the pegmatite, closely associated with manaksite, natrosilite, bario-olgite, sphalerite and late-stage, bladed microcline crystals. Sharp, transparent, colorless, equant chkalovite crystals reach 3 X 5 cm. They are face-rich and complex, and in some cases they combine into clusters up to 8 cm across. Chkalovite crystals also occur commonly within manaksite aggregates.

Chlorbartonite [K.sub.6][Fe.sub.24][S.sub.26](Cl,S)

Chlorbartonite is a recently described new mineral from the Khibiny alkaline massif (Yakovenchuk et al., 2003); it has also been referred to as "Cl-bartonite" in specimens from its occurrence at Coyote Peak, California (Czamanske et al., 1981). The Palitra pegmatite is the first occurrence of the species in the Lovozero massif. Together with bartonite, it forms dark bronze-brown, granular masses to 5 mm X 1 cm. Numerous small (to 0.3 mm) flattened monomineralic chlorbartonite grains in ussingite and serandite were also found. Chlorbartonite was confirmed by its chemical composition and X-ray powder diffraction pattern.

Eudialyte [Na.sub.15][Ca.sub.6](Fe,Mn)[.sub.3][Zr.sub.3][Si.sub.25][O.sub.72](OH,Cl,F)

Eudialyte is widespread in peripheral parts of the Palitra pegmatite. It occurs as brownish red and orange-red irregular grains up to 6 X 20 cm and aggregates up to 30 cm. It is closely associated with aegirine, arfvedsonite, lorenzenite, microcline, nepheline, villiaumite, etc.

[FIGURE 11 OMITTED]

Ferronordite-(Ce) [Na.sub.3]SrCeFe[Si.sub.6][O.sub.17] and Nordite-(Ce) [Na.sub.3]SrCeZn[Si.sub.6][O.sub.17]

Ferronordite-(Ce) and nordite-(Ce) form a continuous isomorphous series and are visually indistinguishable. Both minerals are typical of the late-stage assemblages. They form transparent, coffee-colored, well-formed tabular (flattened on {100}) crystals up to 5 mm, in most cases split and combining into groups, rosettes and spherules up to 1 cm. They overgrow ussingite, analcime and aegirine linings on the cavity walls. Commonly nordite-(Ce) and ferronordite-(Ce) are included in natrosilite and villiaumite. Samples from the Palitra pegmatite mostly correspond to intermediate members of the nordite-(Ce)/ferronordite-(Ce) series.

Galena PbS

Galena forms isometric grains and sharp cuboctahedral crystals (sometimes skeletal) up to 1 cm associated with sphalerite and lollingite.

Kapustinite [Na.sub.5.5][Mn.sub.0.25]Zr[Si.sub.6][O.sub.16](OH)[.sub.2]

Kapustinite, a new mineral of the lovozerite group discovered in the Palitra pegmatite (Pekov et al., 2003b), was named for Yury L. Kapustin (1933-2002), an outstanding researcher who made great contributions to our understanding of alkaine complexes and who studied the lovozerite group in detail. Kapustinite forms equant grains from 5 mm to 4 cm and aggregates to 8 cm; some of the grains have rounded rhombohedral and hexagonal cross-sections. The mineral is transparent, with a dark cherry-red color, sometimes with a brownish tint, and a vitreous luster. No cleavage has been observed. The fracture is conchoidal. Kapustinite is an early-stage mineral which crystallized simultaneously with blocky microcline and eudialyte. Kapustinite grains in sodalite, ussingite, analcime and natrosilite are often surrounded by kazakovite rims. In some cases the rims are more complex, their inner parts consisting of kazakovite and their outer parts of a mixture of ussingite and mangan-neptunite.

[FIGURE 12 OMITTED]

[FIGURE 13 OMITTED]

[FIGURE 14 OMITTED]

Kazakovite [Na.sub.6]MnTi[Si.sub.6][O.sub.18]

Kazakovite is a relatively common mineral in the core of the Palitra pegmatite. Its sharp, yellow-brown crystals to 7 mm show the faces of two rhombohedrons. The crystals are typically included in natrosilite. Equant grains of kazakovite to 1.5 cm occur in ussingite and sodalite. The grains are concentrically zoned: the dark brown cores are enriched by Zr (Ti : Zr = 2.5-3) whereas the honey-yellow peripheral zones are Zr-poor (Ti : Zr = 7-10). Transparent brownish yellow kazakovite rims to 3 mm thick sometimes surround kapustinite grains. Kazakovite in the Palitra pegmatite is very fresh and water-free. The occurrence of this mineral, typically very unstable in the presence of water, is one of the most convincing pieces of evidence that hydrothermal activity in the Palitra pegmatite has been absent, or at least insignificant.

[FIGURE 15 OMITTED]

[FIGURE 16 OMITTED]

[FIGURE 17 OMITTED]

Lamprophyllite [Na.sub.2](Sr,Ba)[.sub.2](Ti,Fe,Mn)[.sub.3](Si[O.sub.4])[.sub.4](OH,F)[.sub.2]

Lamprophyllite is a subordinate mineral of the eudialyte-aegirine-microcline zone. It forms radiating "stars" up to 3 cm in diameter consisting of long-prismatic golden brown crystals, the "stars" most commonly situated among green fibrous aegirine.

Lollingite Fe[As.sub.2]

Lollingite occurs as individual tabular and prismatic crystals up to 7 mm with silvery white color and bright metallic luster. It is commonly associated with galena in aggregates of ussingite, sodalite and aegirine.

Lomonosovite [Na.sub.2][Ti.sub.2][Si.sub.2][O.sub.9] * [Na.sub.3]P[O.sub.4]

Lomonosovite is abundant in the core of the pegmatite. It forms dark brown to almost black lamellar and tabular crystals to 12 cm long and 1.5 cm thick, with bright vitreous luster. Some of the crystals are sharp, with numerous small steps on the {001} face. Complex twins are common. Some crystals are split and combine to form fanlike clusters. Monomineralic lomonosovite aggregates up to 20 cm are not uncommon at the locality. Some lomonosovite occurs in association with structurally related vuonnemite, but oriented parallel intergrowths of these minerals have not been found in the Palitra pegmatite. In the peripheral zones of the pegmatite, lomonosovite occurs as lamellae to 5 cm in the centers of large aegirine spheroids and in aegirine-eudialyte-lorenzenite aggregates. Unlike the majority of other Lovozero pegmatites, the Palitra contains absolutely fresh lomonosovite without replacement by murmanite. Rarely, small bornemanite spherules replace lomonosovite on its contact with natrosilite.

[FIGURE 18 OMITTED]

[FIGURE 19 OMITTED]

[FIGURE 20 OMITTED]

Lorenzenite [Na.sub.2][Ti.sub.2][Si.sub.2][O.sub.9]

Lorenzenite is a common mineral of the eudialyte-aegirine-microcline zone. It forms dark brown coarse prismatic crystals and irregular grains to 3 X 5 cm.

Manaksite NaKMn[Si.sub.4][O.sub.10]

Manaksite is one of the most remarkable minerals of the Palitra pegmatite. Before the discovery of this pegmatite, two localities for manaksite were known; in both it occurs as small grains. It was first described in pegmatitic rock at Mt. Alluaiv in the Lovozero massif as grains to 3 mm and aggregates to 5 mm (Khomyakov et al., 1992). Later, it was found as a rare accessory mineral in the rischorrites of the neighboring Khibiny alkaline massif (Ageeva, 2000). In the core of the Palitra pegmatite, manaksite forms beautiful prismatic crystals to 8 X 20 cm and crystal clusters to several kilograms (!). Individual crystals of this astounding size were previously unknown, even for fenaksite, NaKFe[Si.sub.4][O.sub.10], the isostructrural Fe-dominant analog of manaksite which constitutes a rock-forming mineral in several rischorritic pegmatites in the Khibiny massif. The sharp crystals of manaksite from the Palitra pegmatite are bounded by faces {001}, {011}, {010}, {032}, {401}, {201} and {233}. Manaksite is pinkish yellow to grayish pink. Small fragments are almost colorless, and transparent. The mineral is easily identified visually because of its bright pearly luster on a broken surface, two directions of perfect cleavage parallel to the crystal elongation, and very typical splintery fracture. Manaksite can be easy split into thin needles and fluffed up like asbestos. The empirical formula of manaksite from Palitra is: [Na.sub.1.03][K.sub.0.99]([Mn.sub.0.84][Fe.sub.0.17][Mg.sub.0.03])[.sub.[SIGMA]1.04][Si.sub.3.975][O.sub.10]. This mineral is closely associated with natrosilite, villiaumite, ussingite, analcime, vuonnemite, chkalovite, bario-olgite, steenstrupine-(Ce), and sphalerite. Manaksite is unstable; several minerals commonly replace it in the Palitra pegmatite. Some manaksite crystals are partially or completely replaced by aggregates of pale pink Ca-free serandite and polychromatic aegirine. Prismatic to acicular crystals of these secondary minerals are in most cases oriented parallel to the elongation of the manaksite crystal. Films and crusts of bright yellow zakharovite commonly replace manaksite in cracks in the crystal surfaces.

[FIGURE 21 OMITTED]

Mangan-neptunite K[Na.sub.2]Li(Mn,Fe)[.sub.2][Ti.sub.2][Si.sub.8][O.sub.24]

Mangan-neptunite occurs as a minor mineral in ussingite areas in the core. It forms dark red prismatic crystals up to 5 mm, in some cases closely associated with kazakovite. Mangan-neptunite from the Palitra pegmatite is Fe-rich: Mn : Fe = 1.15-1.20.

Microcline KAl[Si.sub.3][O.sub.8]

Microcline is one of the major rock-forming minerals of the pegmatite. Its white and pale greenish crystalline blocks reach 15 X 60 cm and are the largest mineral masses in the pegmatite. Ussingite and sodalite commonly replace microcline in cracks in its crystals. A later-stage variety of microcline occurs inside pods of villiaumite, natrosilite and manaksite, where it forms clusters of colorless and pale pink, transparent, blade-like crystals to 3 mm long.

Molybdenite Mo[S.sub.2]

Molybdenite occurs rarely as hexagonal platelets and rosettes to 3 mm in diameter on analcime and ussingite. It is typically found inside natrosilite-filled vugs.

[FIGURE 22 OMITTED]

[FIGURE 23 OMITTED]

Nalipoite Na[Li.sub.2]P[O.sub.4]

Nalipoite is a very rare mineral, previously described only from the hyperagpaitic derivatives of the Mont Saint-Hilaire alkaline complex, Quebec (Chao and Ercit, 1991). In the Palitra pegmatite, nalipoite occurs as sharp prismatic crystals to 1 X 1 X 7 mm bounded by faces {100}, {010} and {001}. These crystals are commonly split and combine to form sheaf-like clusters which are situated on the walls of cavities later filled by natrosilite and villiaumite. Nalipoite, together with nordite-(Ce), ferronordite-(Ce) and bornemanite, also forms overgrowths on analcime, ussingite and lomonosovite. The mineral is transparent and colorless, and has a vitreous luster. After dissolution of the surrounding natrosilite or villiaumite, nalipoite crystal surfaces become white and slightly corroded. Nalipoite from the Palitra pegmatite contains (by weight) 25.11% [Na.sub.2]O and 52.72% [P.sub.2][O.sub.5]; Li was not detected. Its X-ray powder diffraction pattern is identical to that for one of the samples from Mont Saint-Hilaire published by G. Y. Chao and T. S. Ercit (1991).

Natrolite [Na.sub.2][Al.sub.2][Si.sub.3][O.sub.10] * 2[H.sub.2]O

Natrolite forms massive granular pods to 5 X 10 cm in the core of the pegmatite. It is colorless and transparent, occurring commonly in ice-like or saccharoidal drusy aggregates.

Natron [Na.sub.2]C[O.sub.3] * 10[H.sub.2]O

Natron is a post-mining mineral formed after the Palitra pegmatite was uncovered; it is probably a product of the reactions of unstable hypersodic minerals with C[O.sub.2] in the air. It forms white efflorescences on the walls and on loose pieces of pegmatite.

[FIGURE 24 OMITTED]

Natrosilite [Na.sub.2][Si.sub.2][O.sub.5]

Natrosilite forms very large individual crystals and aggregates in the core of the Palitra pegmatite. Grains up to 6 cm had been known from numerous other pegmatites in the Lovozero massif (Timoshenkov et al., 1975; Pekov, 2000); here, however, natrosilite single-crystal blocks to 20 X 30 X 30 cm and aggregates weighing to several dozen kilograms have been found! It is a rock-forming mineral in the core of the pegmatite, and it encloses sharp crystals of many other minerals; these include manaksite, nordite-(Ce), ferronordite-(Ce), kazakovite, chkalovite, nalipoite, vitusite-(Ce), vuonnemite, lomonosovite and serandite. Natrosilite is a mica-like mineral: it is elastic, with perfect one-directional cleavage and very pronounced pearly to vitreous luster on fresh cleavage surfaces. In most cases its blocks have no crystal faces, but coarse faces have been observed in rare instances. Natrosilite is colorless to pale pinkish yellow; if the natrosilite block is thick, it appears pearly white. Waterclear, gem-quality tablets to 5 mm thick are occasionally observed, but in general natrosilite is semi-transparent because of an abundance of microfractures and gas-liquid inclusions, the gas portion of most of these being carbon monoxide. An interesting property of natrosilite from the Palitra pegmatite is its pronounced triboluminescence: when its lamellae are broken, a bright lilac to violet flash is observed. This phenomenon is probably caused by combustion of CO released from the inclusions.

[FIGURE 25 OMITTED]

Natrosilite and dark red villiaumite were the last pegmatitic minerals to form; they precipitated simultaneously into cavities from the last portion of the water-poor melt, by this stage maximally enriched in Na and F. Natrosilite is very unstable in the presence of water. It is replaced by revdite in cavities and cracks. In the moist air of the underground mine, hydrolysis of natrosilite is very rapid; the mineral becomes covered by a gelatinous sodium hydrate silicate. In dry air, this "glue" alters to a mixture of opal and semi-amorphous hydrous Na silicates. Blocks of natrosilite up to several centimeters in size can be completely dissolved by flowing water in three to five days, even at room temperature.

[FIGURE 26 OMITTED]

Nepheline (Na,K)AlSi[O.sub.4]

Nepheline is concentrated, for the most part, in the thin top zone of the Palitra pegmatite, where it is very common. Its coarse, elongated crystals, to 4 X 12 cm, form brush-like crusts. The crystals are zoned: their peripheral parts are semitransparent green and their cores are yellowish to colorless and water-clear. Gemquality areas up to 1 cm are not uncommon. Nepheline also occurs as a subordinate mineral in the eudialyte-aegirine-microcline zone.

Nordite-(Ce): see Ferronordite-(Ce)

Opal Si[O.sub.2] * n[H.sub.2]O

Opal is a post-mining mineral, a final product of natrosilite alteration after its contact with mine water. Crusts of colorless, white, bluish and brownish opal are observed on the walls of the underground workings.

Pautovite Cs[Fe.sub.2][S.sub.3]

Pautovite, a new mineral from the Palitra pegmatite and the cesium analog of rasvumite, was recently approved by the IMA Commission on New Minerals and Mineral Names (No. 2004-005). It is named in honor of Leonid A. Pautov (born 1958), outstanding Russian mineralogist and specialist in physical methods for the study of minerals, for his significant contributions to the mineralogy of alkaline pegmatites and the mineralogy of cesium (Pekov et al., 2005). Pautovite occurs as isolated coarse prismatic to acicular crystals up to 0.12 mm long and up to 0.005 mm (very rarely up to 0.015 mm) thick. Some crystals are slightly curved and split. Pautovite typically forms intergrowths, and in many cases it occurs in parallel growth with earlier-formed needle-shaped to filiform crystals of belovite-(Ce) in cavities. Dark pautovite individuals are visible, in spite of their small size, on the surface of white belovite-(Ce) "cotton." Some pautovite crystals were observed on ussingite and microcline and as inclusions in massive red villiaumite in cavities. The mineral is dark steel-grey with metallic luster, but in moist air it becomes dull black. Pautovite is (after galkhaite) the second known natural sulfide with essential cesium to be described, and it is one of the richest cesium minerals known. Its chemical composition is: K 0.21, Rb 1.31, Cs 36.12, Tl 0.50, Fe 33.80, S 28.85, total 100.79 weight %. It corresponds to the empirical formula: ([Cs.sub.0.91][Rb.sub.0.05][K.sub.0.02][Tl.sub.0.01])[.sub.[SIGMA]0.99][Fe.sub.2.02][S.sub.3.00].

[FIGURE 27 OMITTED]

Phosinaite-(Ce) [Na.sub.13][Ca.sub.2]Ce[[Si.sub.4][O.sub.12]](P[O.sub.4])[.sub.4]

Phosinaite-(Ce) is a minor mineral of the core of the Palitra pegmatite. Sprays of its coarse columnar, chocolate-brown crystals (to 1 X 15 mm) with resinous luster were found in ussingite. Grayish brown phosinaite-(Ce) "stars" up to 2 cm in diameter are found included in natrosilite. They consist of long prismatic crystals with an almost quadrangular cross-section, commonly forming parallel intergrowths with morphologically similar pale pink serandite crystals. Chemically, phosinaite-(Ce) from the Palitra pegmatite is most common, with the ratios of Nd to La (Ce:La:Nd = 3.6:1:1.7) which are typical for this mineral. Vitusite-(Ce) may replace phosinaite-(Ce) in the Palitra pegmatite, as in other Lovozero pegmatites.

Potassicarfvedsonite K[Na.sub.2][Fe.sub.4.sup.2+][Fe.sup.3+][Si.sub.8][O.sub.22](OH)[.sub.2]

Potassicarfvedsonite is a new amphibole recently approved by the IMA Commission on New Minerals and Mineral Names (No. 2003-043). It was described simultaneosly from three alkaline massifs: Ilimaussaq in South Greenland (Kangerluarssuk area), Lovozero (the Palitra pegmatite) and Khibiny (Kukisvumchorr Mountain), the latter two on the Kola Peninsula (Pekov et al., 2004b). In the Palitra pegmatite, potassicarfvedsonite forms greenish blue to dark grayish blue acicular crystals to 0.1 X 2 mm, commonly combined in bunches and hedgehog-like clusters to 4 mm. It also occurs as massive nodules to 1.5 cm across, consisting of thin acicular to fibrous individuals. Potassicarfvedsonite aggregates are found in ussingite cavities, and, together with late-stage Ca-free serandite, inside partially altered manaksite crystals. For comparison, large earlier-stage arfvedsonite crystals are widespread in the peripheral zone of the pegmatite.

[FIGURE 28 OMITTED]

[FIGURE 29 OMITTED]

Revdite [Na.sub.2][Si.sub.2][O.sub.5] * 5[H.sub.2]O

Revdite, a product of low-temperature hydrothermal activity, is the last endogenetic mineral of the Palitra pegmatite. Revdite was found only in a few small cavities--no larger than 2 mm X 1 cm. Different morphological varieties of revdite have been observed in the Palitra pegmatite. Small (0.1 mm), colorless and transparent, short prismatic crystals with bright vitreous luster form sprays in vugs within ussingite and villiaumite aggregates. Similar but coarser, translucent white to greenish crystals overgrow natrosilite surfaces. Snow-white fibrous revdite replacing natrosilite forms crusts up to 0.1 mm thick. Pale brown and white brushes and spherules consisting of coarse lath-like revdite crystals up to 0.2 mm long have been found in cavities of microcline blocks. Loose aggregates (up to 1 cm) of pale brown, fine-grained revdite fill some cavities in the core of the pegmatite.

[FIGURE 30 OMITTED]

[FIGURE 31 OMITTED]

Serandite [Na.sub.2]H[Mn.sub.2][Si.sub.3][O.sub.9]

Serandite is a common mineral in the core of the Palitra pegmatite. Its salmon-pink and pinkish yellow, coarse, lath-like crystals, up to 8 cm long but in most cases curved and split, are associated with ussingite and villiaumite. Well-terminated pinkish yellow and orange serandite crystals up to 4 cm are included in natrosilite. Another morpological variety of serandite is pale pink, transparent crystals to 1 X 1 X 10 mm with quadrangular or octagonal cross sections. Usually these crystals replace manaksite, and they are rarely observed in natrosilite or villiaumite, closely associated with phosinaite-(Ce). Curved, bright pink serandite platelets up to 5 mm were found in pseudomorphs after manaksite, together with polychromatic aegirine. Serandite replacing manaksite is almost Ca-free, probably because Ca is absent in manaksite. Serandite included in ussingite is Ca-enriched and close to manganoan pectolite in its chemical composition: studied samples are characterized by Mn:Ca = 1.02.

[FIGURE 32 OMITTED]

[FIGURE 33 OMITTED]

Sodalite [Na.sub.4](AlSi[O.sub.4])[.sub.3]Cl

Sodalite is one of the major minerals in the core of the Palitra pegmatite. Massive aggregates of sodalite to 25 cm across are colorless or white; some show pale purple areas. Grains of villiaumite and analcime included in white sodalite are in some cases surrounded by rims of deep red sodalite. Grayish green sodalite occurs as aggregates associated with analcime and ussingite. Under longwave ultraviolet light, colorless sodalite strongly fluoresces orange, while green sodalite shows a weak orange response. Pale purple sodalite shows practically no fluorescence. Sodalite and eudialyte form reaction borders on the contacts of the pegmatite with the bedrock.

Sphalerite ZnS

Sphalerite is the most abundant sulfide mineral in the Palitra pegmatite. It forms aggregates of yellow-brown transparent lamellae to 5 mm, twinned on (111), which are included in natrosilite and villiaumite, and it is closely associated with ussingite and sodalite. Sharp tetrahedral crystals and arborescent skeletal crystals of sphalerite occur inside natrosilite.

Steenstrupine-(Ce) [Na.sub.14](REE, Th)[.sub.6](Mn, Fe, Ti)[.sub.4](OH)[.sub.2](P[O.sub.4])[.sub.7]([Si.sub.6][O.sub.18])[.sub.2] * n[H.sub.2]O

Steenstrupine-(Ce) is common in the core of the Palitra pegmatite. It occurs as translucent, red-brown, rhombohedral crystals and equant grains up to 5 cm associated with microcline, ussingite, sodalite, analcime, and rarely natrosilite. It contains 10-11 weight % Th[O.sub.2] and 0.6% U[O.sub.2], and is therefore radioactive.

[FIGURE 34 OMITTED]

Thorosteenstrupine [Na.sub.0-5][Ca.sub.1-3](Th,REE)[.sub.6](Mn,Fe,Al,Ti)[.sub.4-5][[Si.sub.6](O,OH)[.sub.18]][.sub.2][(Si,P)[O.sub.4]][.sub.6](OH,F,O)[.sub.x] * n[H.sub.2]O

Thorosteenstrupine, the thorian analog of steenstrupine-(Ce) (Pekov et al., 1997), occurs as crystals to 1.5 mm on microcline, ussingite, analcime and sodalite. It was found after enclosing villiaumite was dissolved away by water. Palitra is the first known locality for sharp thorosteenstrupine crystals; many are tabular and rhombohedral-pinacoidal, bounded by faces {001}, {101} and {401}, while equant crystals also show the {021} face (hkl indices are assigned by analogy with steenstrupine-(Ce) morphology). Thorosteenstrupine is dark red-brown and translucent. Unlike the abundant, relatively early-stage steenstrupine-(Ce), thorosteenstrupine is a rare late-stage mineral.

Troilite FeS

Troilite occurs as bronze-colored grains to 1 mm included in aggregates of bartonite and chlorbartonite.

[FIGURE 35 OMITTED]

Ussingite [Na.sub.2]Al[Si.sub.3][O.sub.8](OH)

Ussingite is a common mineral of the core of the Palitra pegmatite, although not a major constituent as it is in numerous other Lovozero pegmatites. The ussingite content of the polymineralic aggregates of the Palitra core is not more than 20% by volume. It forms massive, pale purple masses to 10 cm and is closely associated with sodalite, steenstrupine-(Ce), lomonosovite, vuonnemite and serandite. Ussingite replaces analcime; partial and complete pseudomorphs of pale purple ussingite after sharp analcime crystals are common. The surface of some of these pseudomorphs is formed by colorless, oblique-angled tabular or prismatic ussingite crystals to 3 mm.

Villiaumite NaF

Villiaumite, of at least three different generations, is widespread in all assemblages in the Palitra pegmatite. Bright red, first-generation villiaumite (designated villiaumite-I) forms abundant arborescent and cuboctahedral inclusions in large crystals of other early minerals including eudialyte, lorenzenite, lomonosovite and especially microcline. Beautiful graphic intergrowths of red villiaumite-I and greenish white microcline are not uncommon. The length of such villiaumite "trees," which are actually skeletal crystals, can reach 10 cm. Ruby-colored and dark red second-stage villiaumite-II forms equant, commonly rounded inclusions up to 3 cm in analcime and sodalite. The third-generation, dark red villiaumite-III, occurs as aggregates to 30 cm in the core of the Palitra pegmatite, filling cavities together with simultaneously crystallized natrosilite. It also occurs as graphic intergrowths within natrosilite and villiaumite. In small cavities, well-formed cuboctahedral villiaumite crystals to 1.5 mm have been observed. Villiaumite-III is one of the main constituents of the pegmatite core. Perfect crystals of earlier-formed analcime, serandite, nordite-(Ce), ferronordite-(Ce), vuonnemite, bario-olgite and other minerals are commonly present inside villiaumite-III aggregates.

[FIGURE 36 OMITTED]

[FIGURE 37 OMITTED]

Vitusite-(Ce) [Na.sub.3]Ce(P[O.sub.4])[.sub.2]

Vitusite-(Ce) is a common mineral of the late-stage assemblages. It forms transparent, pale brown, tabular crystals to 8 mm with bright vitreous luster on crystal faces and resinous luster on broken surfaces. Radial clusters of such crystals overgrow analcime, sodalite, ussingite and aegirine, and in most cases they are situated inside natrosilite, only rarely in manaksite or villiaumite. Another morphological variety of vitusite-(Ce) occurs as brown spherules up to 1 mm in diameter forming crusts on serandite crystals in cracks and in the peripheral parts of corroded manaksite crystals. That this morphological variety of vitusite-(Ce) replaced phosinaite-(Ce) is supported by rare-earth-element ratios (Ce:La:Nd = 3.3:1:1.5) which are typical for phosinaite-(Ce), whereas the above-mentioned large crystals of vitusite-(Ce) show a REE ratio common for the species in other localities (Ce:La:Nd = 1.4:1:0.2). Partial pseudomorphs of fine-grained vitusite-(Ce) after phosinaite-(Ce) crystals have been observed in ussingite aggregates. Vitusite-(Ce) fluoresces pale violet in shortwave ultraviolet light.

Vuonnemite [Na.sub.5][Nb.sub.3]Ti([Si.sub.2][O.sub.7])[.sub.3][O.sub.2][F.sub.2] * 2[Na.sub.3]P[O.sub.4]

Vuonnemite is abundant in the core of the pegmatite. Its transparent, bright lemon-yellow lamellae (to 7 cm wide and 5 mm thick) with bright vitreous luster occur included in villiaumite, natrosilite and ussingite together with serandite and sphalerite. Some of these lamellae are curved. When villiaumite-III is carefully dissolved in water, perfect, tabular vuonnemite crystals to 5 mm are sometimes revealed on aegirine.

[FIGURE 38 OMITTED]

[FIGURE 39 OMITTED]

[FIGURE 40 OMITTED]

Wurtzite ZnS

Wurtzite from the Palitra pegmatite represents the first occurrence of the mineral anywhere in the Lovozero massif. It forms red-brown, translucent crystals to 0.5 mm bounded by faces of hexagonal pyramids and terminated by the pedion {001}. The crystals, forming clusters to 1 mm on ussingite and sodalite, were found after dissolving away enclosing villiaumite. Wurtzite was confirmed by the presence of the d = 3.29 [Angstrom] reflection in its X-ray powder diffraction pattern.

Zakharovite [Na.sub.4][Mn.sub.5][Si.sub.10][O.sub.24](OH)[.sub.6] * 6[H.sub.2]O

Zakharovite is an alteration product of manaksite in the Palitra pegmatite. It occurs as bright yellow films and crusts to 0.5 mm thick on manaksite surfaces and in cracks in manaksite crystals. Zakharovite crusts up to several square centimeters have been found. They consist of subparallel, spherulitic or scaly aggregates. Larger zakharovite spherules (to 1.5 mm in diameter) consisting of yellow lamellae are rarely observed in natrosilite near its contact with manaksite.

GEOCHEMICAL AND GENETIC FEATURES

Taking into account the Palitra pegmatite's geological setting, morphology, structure and mineral relations, it is possible to propose that the pegmatite was formed within a closed system from a relatively high-temperature, residual water-poor ("dry") melt oversaturated in alkali (especially Na) volatiles and rare elements. Inside this "bubble" situated under the malignite "shield," a strong differentiation of elements gave rise to the diverse mineral assemblage and the zoning observed. The pegmatite's influence on surrounding rocks was insignificant, causing only thin contactzone reaction rims consisting of sodalite, eudialyte and villiaumite.

The temperatures of mineral formation (except for revdite in cavities) can be determined as approximately 200-450[degrees]C.

An unusual feature of the Palitra pegmatite is that, unlike the majority of hyperagpaitic rocks and pegmatites, it contains no endogenetic carbonates or other minerals containing carbonate ions. These minerals (natrite, thermonatrite, trona, shortite, sidorenkite, cancrinite group members, etc.) occur in alkaline pegmatites where C[O.sub.2] is a common constituent of gas-liquid inclusions. Abundant gas inclusions were found in natrosilite from the Palitra pegmatite, but N. V. Chukanov, using infrared spectroscopy, determined that the major phase of these inclusions is CO, whereas C[O.sub.2] is almost totally absent. This is very rare for alkaline rocks, and it reveals the reducing conditions that must have existed during late stages of the formation of the Palitra pegmatite.

Another interesting feature of the pegmatite is its enrichment in potassium. Such enrichment is abnormal for late-stage assemblages of Lovozero pegmatites, which are usually hypersodic with relatively low K content. The potassium enrichment is reflected in the crystallization of large amounts of manaksite in the Palitra pegmatite. The amounts of the other major and minor elements (Li, Be, Ca, Sr, Ba, Mn, Fe, Zn, Al, REE, Th, Ti, Zr, Nb, P, S, Cl, etc.) are typical for hyperagpaitic derivatives of the Lovozero massif.

The sequence of formation of the mineral assemblages in the Palitra pegmatite is inferred to have been as follows.

Nepheline, which composes the thin top zone of the pegmatite, was the first mineral to form. This corresponds to the normal order of mineral crystallization from an agpaitic melt (Kogarko, 1977). Green fibrous aegirine-I, microcline, eudialyte, arfvedsonite, lorenzenite, lamprophyllite, lomonosovite, kapustinite and villiaumite-I were formed after nepheline.

Polymineralic aggregates mostly consisting of sodian aluminosilicates (sodalite, analcime and ussingite) are judged to have formed later than the aegirine-eudialyte-microcline paragenesis because of the replacement of microcline by ussingite and sodalite. This assemblage also includes black prismatic aegirine-II, villiaumite-II, serandite-I, vuonnemite, kazakovite, steenstrupine, phosinaite, vitusite-I, chkalovite and mangan-neptunite. Minerals observed on the surface of ussingite and analcime after the dissolving of villiaumite and natrosilite are probably products of the next sub-stage: these are natrolite, manaksite, nordite, ferronordite, thorosteenstrupine, bario-olgite, nalipoite, barytolam-prophyllite, and sphalerite. Pseudomorphs of various minerals were formed still later: pale pink serandite-II, polychromatic aegirine-III and zakharovite after manaksite, bornemanite after lomonosovite, and vitusite-II after phosinaite. Cavities were filled by natrosilite and villiaumite-III.

The only low-temperature (late hydrothermal) mineral is revdite. The role of low-temperature mineralization in the Palitra pegmatite is insignificant; in this the Palitra differs from all other known large Lovozero pegmatites.

Generally, the parent medium of the Palitra pegmatite minerals (except perhaps the earliest ones) seems to have been a highly reduced, extremely Na-Fe-oversaturated silicate melt that was water-poor and C[O.sub.2]-free. When rock-forming and early accessory minerals crystallized, rare elements (Be, Ba, REE, Nb, plus Mn and Zn) accumulated, providing for rich mineralization in the core of the pegmatite. The last primary ("dry") minerals to form were natrosilite with abundant inclusions of CO and villiaumite. After the crystallization of minerals of K, Ca, Mn, Fe, Zn, Ti, P, S, Cl and rare elements, the composition of the residual gas-liquid medium was carbonyl-fluoride-silicate-sodic-rich, without significant admixtures of other constituents.

ACKNOWLEDGMENTS

The author is greatly indebted to Nickolay V. Pavlov, chief geologist of the Lovozero Mining Company, and mine geologist Ludmila I. Ksenofontova for their kind support of our work on the Palitra pegmatite. The author is also most grateful to Viktor G. Grishin for his comprehensive assistance; to Anna G. Turchkova, who helped to prepare and preserve specimens of unstable minerals; to Nikita V. Chukanov, Natalia N. Kononkova, Leonid A. Pautov and Atali A. Agakhanov for their participation in the mineral studies; and to Natalia A. Pekova, who prepared the color photographs. Special thanks go to Tony Nikischer, who actively assisted in the appearance of this paper and kindly improved the English of the original manuscript. The author is grateful to Anthony R. Kampf, Thomas P. Moore and Wendell E. Wilson for their editing work.

REFERENCES

AGEEVA, O. A. (2000) A new isomorphous series fenaksite-manaksite. Doklady RAN, 373(3), 363-365 (in Russian).

BUSSEN, I. V., and SAKHAROV, A. S. (1972) Petrologiya Lovozerskogo Shchelochnogo massiva (Petrology of Lovozero Alkaline Massif). Leningrad, Nauka Publishing, 296 pp. (in Russian)

CHAO, G. Y., and ERCIT, T. S. (1991) Nalipoite, sodium dilithium phosphate, a new mineral species from Mont Saint-Hilaire, Quebec. Canadian Mineralogist, 29, 565-568.

CZAMANSKE, G. K., ERD, R. C., LEONARD, B. F., and CLARK, J. R. (1981) Bartonite, a new potassium iron sulfide mineral. American Mineralogist, 66, 369-375.

KHOMYAKOV, A. P. (1995) Mineralogy of Hyperagpaitic Alkaline Rocks. Oxford, Clarendon Press, 223 pp.

KHOMYAKOV, A. P., SEMENOV, E. I., SHUMYATSKAYA, N. G., TIMOSHENKOV, I. M., LAPUTINA, I. P., and SMOL'YANINOVA, N. N. (1980) Olgite, Na(Sr,Ba)P[O.sub.4], a new mineral. Zapiski VMO, 109(3), 347-351 (in Russian).

KHOMYAKOV, A. P., KUROVA, T. A., and NECHELYUSTOV, G. N. (1992) Manaksite, NaKMn[Si.sub.4][O.sub.10], a new mineral. Zapiski VMO, 121(1), 112-115 (in Russian).

KOGARKO, L. N. (1977) Problemy Genezisa Agpaitovykh Magm (Problems of Genesis of Agpaitic Magmas). Moscow, Nauka Publishing, 294 pp. (in Russian).

PEKOV, I. V. (2000) Lovozero Massif: History, Pegmatites, Minerals. Moscow, Ocean Pictures Ltd., 480 pp.

PEKOV, I. V., EKIMENKOVA, I. A., and KONONKOVA, N. N. (1997) Thorosteenstrupine from Lovozero massif and steenstrupine-(Ce)--thorosteenstrupine, an isomorphous series. Zapiski VMO, 126(6), 35-44 (in Russian).

PEKOV, I. V., SHCHERBACHEV, D. K., and KONONKOVA, N. N. (2003a) Bartonite from Lovozero massif (Kola Peninsula). Zapiski VMO, 132(3), 97-101 (in Russian).

PEKOV, I. V., CHUKANOV, N. V., YAMNOVA, N. A., EGOROVTISMENKO, Yu. K., and ZADOV, A. E. (2003b) New mineral kapustinite, [Na.sub.5.5][Mn.sub.0.25]Zr[Si.sub.6][O.sub.16](OH)[.sub.2], from Lovozero massif (Kola Peninsula) and new data on the genetic crystallochemistry of the lovozerite group. Zapiski VMO, 132(6), 1-14 (in Russian).

PEKOV, I. V., CHUKANOV, N. V., KULIKOVA, I. M., ZUBKOVA, N. V., KROTOVA, O. D., SOROKINA, N. I., and PUSHCHAROVSKY, D. Yu. (2004a) New mineral bario-olgite and its crystal structure. Zapiski VMO, 133(1), 41-49 (in Russian).

PEKOV, I. V., CHUKANOV, N. V., LEBEDEVA, Y. S., PUSHCHAROVSKY, D. Yu., FERRARIS, G., GULA, A., ZADOV, A. E., NOVAKOVA, A. A., and PETERSEN, O. V. (2004b) Potassicarfvedsonite, K[Na.sub.2][Fe.sub.4.sup.2+][Fe.sub.3+][Si.sub.8][O.sub.22](OH)[.sub.2], a K-dominant amphibole of the arfvedsonite series from agpaitic pegmatites--Mineral data, structure refinement and disorder in the A site. Neues Jahrbuch fur Mineralogie. Monatshefte. 555-574.

PEKOV, I. V., AGAKHANOV, A. A., BOLDYREVA, M. M., and GRISHIN, V. G. (2005) Pautovite, Cs[Fe.sub.2][S.sub.3], a new mineral species from the Lovozero alkaline complex, Kola Peninsula, Russia. Canadian Mineralogist, 43 (in press).

TIMOSHENKOV, I. M., MEN'SHIKOV, Yu. P., GANNIBAL, L. F., and BUSSEN, I. V. (1975) A natural sodium silicate--natrosilite. Zapiski VMO, 104(3), 317-321 (in Russian).

YAKOVENCHUK, V. N., PAKHOMOVSKY, Ya. A., MENSHIKOV, Yu. P., IVANYUK, G. Yu., KRIVOVICHEV, S. V., and BURNS, P. C. (2003) Chlorbartonite, [K.sub.6][Fe.sub.24][S.sub.26](Cl,S), a new mineral species from a hydrothermal vein in the Khibina massif, Kola Peninsula, Russia: description and crystal structure. Canadian Mineralogist, 41, 503-511.

Igor V. Pekov

Dept. of Mineralogy, Faculty of Geology

Moscow State University

119899 Vorobievy Gory, Moscow, Russia

SOME PETROLOGICAL TERMS

(from JACKSON, J. A., Ed. (1997) Glossary of Geology, Fourth Edition. Alexandria, VA: American Geological Institute.)

Agpaite: A group of feldspathoid-bearing igneous rocks, first described from Ilimaussaq, Greenland, by Ussing in 1912, that includes sodalite-bearing nepheline syenite, naujaite, lujavrite, kakortokite, etc., and is distinguished by having (Na + K)>Al on a molecular or atomic basis. Agpaitic refers generally to crystallization in the presence of excess alkali elements, especially sodium, so that the amount of aluminum oxide is insufficient for the formation of aluminum silicates. Hyperagpaite is an extreme manifestation of this condition.

Alkaline rock: As defined by Shand in 1922, any igneous rock in which the molecular ratio [([Na.sub.2]O + [K.sub.2]O) : [Al.sub.2][O.sub.3] : Si[O.sub.2]] differs from 1:1:6 by deficiency in either [Al.sub.2][O.sub.3] or Si[O.sub.2].

Foyaite: A nepheline syenite containing a predominance of potassium feldspar. Originally described by Blum as synonymous with nepheline syenite, and later applied by Brogger to nepheline syenite with trachytic texture. Its name is derived from Foya, Portugal.

Ijolite: A series of plutonic rocks containing nepheline and 30-60% mafic minerals, generally clinopyroxene, and including titanite, apatite and andradite; also, any rock of that series ... urtite is a type rich in nepheline. Named by Ramsay in 1891 for Ijola (Iivaara), Finland.

Lujavrite: A coarse-grained trachytic eudialyte-bearing nepheline syenite, containing thin parallel feldspar crystals with interstitial nepheline grains and acicular aegirine crystals. The rock was originally described by Brogger in 1890 from Luijaur (Lujavr), now Lovozero, Kola Peninsula, Russia.

Malignite: A mafic nepheline syenite which has more than 5% nepheline and roughly equal amounts of pyroxene and potassium feldspar. The name, given by Lawson in 1896, is derived from the Maligne River, Ontario, Canada.

Rischorrite: A variety of nepheline syenite in which nepheline is poikilitically enclosed in microcline perthite. ("Poikilitic" refers to a texture in which small crystals of one mineral are irregularly scattered within a larger anhedral crystal of another mineral.) The name, given by Kupletsky in 1932, is for Rischorr in the Khibina complex, Kola Peninsula, Russia.

Urtite: A light-colored member of the ijolite series that is composed chiefly of nepheline and 0-30% mafic minerals, especially aegirine and apatite. The name, given by Ramsay in 1896, is for Lujavr-Urt (now Lovozero), Kola Peninsula, Russia.
Table 1. Chemical composition (wt. %) of bartonite (1), chlorbartonite
(2), troilite (3), sphalerite (4), wurtzite (5) and lollingite (6) from
the Palitra.

             1       2       3       4      5       6

Na          0.04    0.02
K           9.66    9.53
Tl          0.20    0.20
Cu          0.18    0.15
Zn          0.07    0.21          64.56   59.40
Mn                                 0.37    0.55
Fe         53.93   53.69   62.07   2.26    7.64  24.26
Co          0.11    0.08                          2.27
Ni          0.14    0.15
As                                               72.81
S          35.82   35.01   36.72  32.43   32.90   0.56
Cl          0.02    1.13
Total     100.26  100.17   98.79  99.62  100.49  99.90

Table 2. Chemical composition (wt. %) of bario-olgite (1), belovite-(Ce)
(2), vitusite-(Ce) (3-4), steenstrupine-(Ce) (5), thorosteenstrupine
(6-7), phosinaite-(Ce) (8-9), ferronordite-(Ce) (10) and nordite-(Ce)
from the Palitra.

                       1       2        3      4      5        6

[Na.sub.2]O           14.78   4.32    21.91  24.05   6.26    14.16
[K.sub.2]O             0.87   0.11
CaO                    0.32            1.20   1.18   2.05     0.50
SrO                   16.57  41.44     1.67          0.33
BaO                   31.17   1.32     0.29
MgO                                                  0.30     1.20
MnO                    0.39                   0.92   7.87     6.73
FeO                                                  1.55     1.67
ZnO                                                  0.22
[Al.sub.2][O.sub.3]                                           0.68
[La.sub.2][O.sub.3]    2.41   5.49    14.42   5.04   9.03     1.41
[Ce.sub.2][O.sub.3]    1.90  12.41    20.26  16.77  13.38     6.39
[Pr.sub.2][O.sub.3]    0.10   1.19     1.30   2.13   1.12     0.14
[Nd.sub.2][O.sub.3]    0.16   2.43     2.29   8.01   2.86     3.34
[Sm.sub.2][O.sub.3]                    0.71   0.74
Th[O.sub.2]                            0.17   2.99  10.24    20.13
U[O.sub.2]                                           0.64     0.99
Si[O.sub.2]            0.08            0.05   3.23  30.84    35.21
[P.sub.2][O.sub.5]    31.77  28.62    34.74  33.90   6.22     5.43
Total                100.52  98.33*   99.01  98.96  94.46*   98.29*

                       7       8      9      10     11

[Na.sub.2]O          15.33   29.80   25.87  12.47  12.12
[K.sub.2]O                            0.12
CaO                   1.44    6.11    7.33   0.30   0.27
SrO                                         12.86  12.66
BaO                                          0.80   0.87
MgO                                   0.20   0.45   0.46
MnO                   7.30    2.57    2.24   1.93   2.05
FeO                   1.98            0.06   2.50   2.36
ZnO                                   0.19   2.61   2.95
[Al.sub.2][O.sub.3]                          0.06   0.06
[La.sub.2][O.sub.3]   1.50    2.05    2.57   8.35   8.53
[Ce.sub.2][O.sub.3]   6.06    7.35    9.04  11.07  11.23
[Pr.sub.2][O.sub.3]   1.05    1.17    0.73   0.27   0.44
[Nd.sub.2][O.sub.3]   2.13    3.53    3.75   0.68   0.82
[Sm.sub.2][O.sub.3]                   0.26
Th[O.sub.2]          23.39            0.64
U[O.sub.2]            3.83
Si[O.sub.2]          30.13   21.63   21.04  44.82  44.61
[P.sub.2][O.sub.5]    2.54   24.23   23.20
Total                96.68   98.44   97.24  99.17  99.43

NOTE: vitusite-(Ce): 3 -- large crystal, 4 -- spherulite replacing
phosinaite-(Ce); phosinaite-(Ce): 8 -- thick crystal in ussingite,
9 -- thin needle forming rosette in natrosilite.
* Totals also include: #2 -- 1.50 F, -0.63 -O=[F.sub.2]; #5 -- 1.06
Ti[O.sub.2], 0.49 Zr[O.sub.2]; #6 -- 0.31 PbO.

Table 3. Chemical composition (wt. %) of aegirine (1-2), serandite
(3-5), arfvedsonite (6), potassicarfvedsonite (7), manaksite (8),
zakharovite (9) and ussingite (10) from the Palitra.

                       1       2       3      4      5      6

[Na.sub.2]O          13.31    13.11   9.11   9.54  10.95   8.52
[K.sub.2]O                            0.02                 1.64
CaO                   0.81            0.10   0.13  14.04   0.47
MgO                   0.84     0.38   0.03          0.02   6.76
MnO                   0.76     1.60  34.78  35.31  18.28   1.99
FeO                                   1.40   0.88   0.61  16.83**
[Fe.sub.2][O.sub.3]  26.82    33.11                        7.02**
[Al.sub.2][O.sub.3]   0.80     0.97                        1.62
Si[O.sub.2]          51.96    51.24  51.23  51.74  52.71  49.72
Ti[O.sub.2]           3.13     0.03                        2.22
Total                99.04*  100.43  96.67  97.60  96.61  96.88*

                       7         8      9      10

[Na.sub.2]O           7.65      8.14  10.04  20.25
[K.sub.2]O            3.76     11.90          0.04
CaO                   0.09             0.13   0.02
MgO                   4.80      0.27
MnO                   3.26     15.24  23.04
FeO                  13.82**    3.10   5.00
[Fe.sub.2][O.sub.3]   8.50**                  0.05
[Al.sub.2][O.sub.3]   0.51                   16.07
Si[O.sub.2]          52.82     61.20  51.91  59.40
Ti[O.sub.2]           0.77
Total                97.52*    99.85  90.12  95.83

NOTE: aegirine: 1 -- black thick crystal, 2 -- red crystal in
Pseudomorph after manaksite; serandite: 3 -- pale-pink bar-shaped
crystal in pseudomorph after manaksite, 4 -- bright-pink platy crystal
in pseudomorph after manaksite, 5 -- large salmon-pink crystal in
ussingite.
* Totals also include: #1 -- 0.61 Zr[O.sub.2]; #6 -- 0.11 Cl, -0.02
-O=[Cl.sub.2]; #7 -- 0.73 [Li.sub.2]O, 0.11 ZnO, 1.21 F, -0.51
-O=[F.sub.2].
** Calculated from [Fe.sub.tot].

Table 4. Chemical composition (wt. %) of kapustinite (1), kazakovite
(2-4), eudialyte (5), barytolamprophyllite (6-7), bornemanite (8-9) and
mangan-neptunite (10) from the Palitra.

                       1        2      3      4      5       6      7

[Na.sub.2]O           24.42   26.89  26.27  28.47  12.32    9.35  10.13
[K.sub.2]O             0.02                         0.49    1.08   1.12
CaO                    0.18    0.65   0.74   0.46   6.07    0.12   0.16
SrO                                                         6.45   5.43
BaO                                                        15.27  17.75
MgO                    0.02           0.06   0.02           0.16   0.22
MnO                    2.36    5.46   5.43   4.56   2.43    3.77   3.95
ZnO                    0.05                                        0.17
FeO                                                 5.87    0.87   1.38
[Fe.sub.2][O.sub.3]    0.36    1.87   2.30   2.25
[Al.sub.2][O.sub.3]                                         0.20   0.20
Si[O.sub.2]           52.82   54.27  54.37  54.15  52.82   28.74  27.27
Ti[O.sub.2]            0.54    5.95   5.62   6.52   0.59   27.81  29.28
Zr[O.sub.2]           16.38    2.42   3.32   1.40  15.04
[Nb.sub.2][O.sub.5]            0.81   0.66   1.28   1.07    0.72   0.55
[P.sub.2][O.sub.5]
Total                100.84*  98.32  98.77  99.13  97.55*  94.54  98.14

                       8        9      10

[Na.sub.2]O          25.58    27.06    7.16
[K.sub.2]O            0.41     0.83    5.05
CaO                   0.24
SrO
BaO                   8.63     8.35
MgO                                    0.18
MnO                   1.58     1.18    8.52
ZnO
FeO                                    7.29
[Fe.sub.2][O.sub.3]   0.65     0.38
[Al.sub.2][O.sub.3]                    0.15
Si[O.sub.2]          27.38    29.98   52.37
Ti[O.sub.2]          14.92    14.04   16.39
Zr[O.sub.2]
[Nb.sub.2][O.sub.5]  10.06     9.70    0.53
[P.sub.2][O.sub.5]    7.27     7.14
Total                96.72*   98.66   97.64

NOTE: kazakovite: 2 -- rim around kapustinite, 3-4 -- zonal crystal
(3 -- dark-brown core, 4 -- honey-colored rim); barytolamprophyllite:
6 -- spherulite, 7 -- crystal epitactically grown on lorenzenite;
bornemanite: 8 -- spherulite on lomonosovite, 9 -- segregation in
villiaumite.
* Totals also include: #1 -- 0.17 [Y.sub.2][O.sub.3], 0.20
[Ce.sub.2][O.sub.3], 0.24 [Nd.sub.2][O.sub.3], 0.28 U[O.sub.2], 2.80
[H.sub.2]O; #5 -- 1.10 Cl, -0.25 -O=[Cl.sub.2]; #8 -- 0.91 F, -0.38
-O=[F.sub.2].
COPYRIGHT 2005 The Mineralogical, Inc.
No portion of this article can be reproduced without the express written permission from the copyright holder.
Copyright 2005 Gale, Cengage Learning. All rights reserved.

Article Details
Printer friendly Cite/link Email Feedback
Author:Pekov, Igor V.
Publication:The Mineralogical Record
Geographic Code:4EXRU
Date:Sep 1, 2005
Words:9525
Previous Article:Photo caption errata.
Next Article:The minerals of west-central Illinois.
Topics:

Terms of use | Privacy policy | Copyright © 2022 Farlex, Inc. | Feedback | For webmasters |