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Journal/NDM46 2011 eng
New Data on Minerals. 2011. Volume 46. 168 pages, 138 photos, drawings and schemes.
Publication of Institution of Russian Academy of Sciences, FersmanMineralogicalMuseum RAS.
- 1 Summary
- 2 Editorial Board
- 3 Publishing group
- 4 Сontent
This issue includes the articles about new mineral species found from rocks of the Dara-i-Pioz alkaline massif, Tajikistan:
byzantievite, Ba, Ca, REE, Ti, and Nb silico-phospho-borate with complex structure and orlovite, titanium analogue of
polylithionite, which is a new member of mica group. Rare minerals, rooseveltite and preisingerite from the Oranzhevoye ore
f ield, Verkhne-Kalganinsky massif, Magadan region, Russia, mannardite from carbonaceous-siliceous schists, South
Kirgizstan and Kazakhstan, and palladoarsenide and mayakite from sulfide of ores of Norilsk field are described. The new data
of fahlores and secondary minerals at the Labedinoe deposit, Central Aldan, Li mineralization from the Glubostrovskoye
granitic pegmatite, South Urals, and mineralogy of wood tin at the Dzhalinda deposit, Khingan-Oloi tin district are given. The
published and novel data of uranium oxides and hydroxides are reviewed. The experimental study of crystallization products
of chalcopyrite solid solution was carried out.
In section “Mineralogical museums and collections”, stone-cutting articles of the Peterhof lapidary factory in the collection of the Fersman Mineralogical Museum, Russian Academy of Sciences are described. The other two articles are devoted to the history of first catalogues of the museum collections and the attribution of marble specimens of Florentine marble mosaic and ruin marble involved in the first Mineral catalogue by M.V. Lomonosov. The exhibition “Amazing stone” held in 2011 in the Fersman Mineralogical Museum and the new acquisitions to the museum 2009–2010 are also reported in this section. An article about Yu.L. Orlov, talented mineralogist, the head of the Fersman Mineralogical Museum from 1976 to 1980, is placed in section “Persons”.
A section “Mineralogical notes” briefly informs about the new data of the process of formation of skeletal crystals of calcite from carst cavities, reports bilibinskite from the cementation zone of gold-telluride deposits (Aginskoe, Kamchatka and Pionerskoe, Syan Mountains), and the minerals from metakimberlites of the Udachnaya-Vostochnaya Pipe, Northern Yakutia.
This journal is interest for mineralogists, geochemists, geologists, workers of natural history museums, collectors, and amateurs of stone.
- Editor in Chief Victor K. Garanin, Doctor in Science, Professor
- Executive Editor Elena A. Borisova, Ph.D.
- Editorial Board Margarita I. Novgorodova, Doctor in Science, Professor,
- Eugeny I. Semenov, Doctor in Science,
- Svetlana N. Nenasheva, Ph.D.,
- Elena N. Matvienko, Ph.D.,
- Marianna B. Chistyakova, Ph.D.,
- Mikhail E. Generalov, Ph.D.
- Photo Michael B. Leybov
- Leader of Publishing group Michael B. Leybov
- Managing Editor Ludmila A. Cheshko
- Art Director Nikolay O. Parlashkevich
- Editor Andrey L. Cheshko
- Design and Layout Ivan A. Glazov
- Translators Maria S. Alferova, Il'ya A. Anisimov, Ivan A. Baksheev, Mark Fed’kun
- Valerii V. Gerasimovskii, Mikhail Povarennykh
- Editors (English Style) Patricia Gray, Frank C. Hawthorne, Peter Modreski
Authorized for printing by Institution of Russian Academy of Sciences, Fersman Mineralogical Museum RAS
Text,photo,drawings andschemes, InstitutionofRussianAcademyof Sciences, Fersman Mineralogical MuseumRAS,2013
Design BRITAN Ltd, 2011
Published by Fersman Mineralogical Museum, BRITAN Ltd Russian Academy of Sciences Box 71 Moscow 117556 Bld. 18/2 Leninsky ProspektMoscow 119071 Russia Phone/fax +7(495) 629G48G12 Phone: +7(495) 952-00-67; fax +7(495) 952-48-50 e-mail: email@example.com e-mail: firstname.lastname@example.org www.minbook.com www.fmm.ru
New Minerals and Their Varieties, New Finds of Rare Minerals, Mineral Paragenesis
A new silico-phosphate of Ba, Ca, REE, Ti, and Nb found in the Darai-Pioz alkaline massif, Tajikistan, has been named byzantievite because of its complex chemical composition and structure, reminiscent of the complex, but well-organized structure of the Byzantine Empire. The new mineral was discovered on a rock composed of microcline, quartz, aegirine and ferrileakeite; accessory minerals are: calcybeborosilite-(Y), pyrophanite, stillwellite(Ce), danburite, thorite and pyrochlore. The new mineral occurs as tabular grains up to 0.5 x 1.8 mm in size and aggregates of these grains up to 2.5 mm in size. Byzantievite is brown with a pale-yellow streak. Luster is vitreous, slightly greasy on fracture surfaces. Cleavage is not observable; fracture is conchoidal. The Mohs’ hardness is 4.5–5. The mean (10 measurements) microhardness VHN is 486 kg/mm2. The measured density is 4.10(3) g/cm3, calculated density is 4.15 g/cm3. Byzantievite is optically negative, uniaxial, ω = 1.940, ε = 1.860 ± 0.005. The new mineral is pleochroic from light brown along ε to very pale brown along ω; absorption is ε >> ω. The symmetry is hexagonal, space group R3, a = 9.128(5); c = 102.1(1) Å; V = 7363 (15) Å3, Z = 3. The crystal structure was solved to R1 = 13.14%. The strong reflections in the X-ray powder – diffraction pattern are (d, Å; I; hkl): 4.02(2)(-1 2 12); 3.95(2)(-222); 3.112(10)(1 1 24; -1 2 24); 2.982(4)(-321; -231); 2.908(2)(1 1 27; -138; 128); 2.885(2)(-3 2 10; -2 3 10); 2.632(2)(030); 2.127(2)(0 0 48). The chemical composition is as follows (electron microprobe, average value and range of content of 60 point analyses; B2O3 was determined by SIMS; H2O on the basis of structural data; wt.%): SiO2 4.73(3.15–5.84), Nb2O5 10.97 (10.35–12.82), P2O5 3.83(2.64–4.88), TiO2 15.21(13.84–16.56), ThO2 1.48(1.48–1.88), UO2 0.55(0.29–0.35), La2O3 4.01(3.27–4.41), Ce2O3 9.19(6.76–9.73), Nd2O3 3.35(3.42–4.42), Pr2O3 1.02(0.17–1.77), Sm2O3 0.71 (0.58–1.23), Dy2O3 1.25(1.05–1.30), Gd2O3 0.95(0.68–1.49), Y2O3 7.39(5.21–9.00), B2O3 5.09(4.38–6.12), FeO 0.49(0.48–0.73), BaO 13.30(12.76–14.91), CaO 8.01(5.41–10.31), SrO 1.95(1.08–2.17), Na2O 0.16 (0.00–0.22), H2O 6.00, F 1.80(1.30–2.08), O=F (-0.76), total is 100.68. The empirical formula, calculated on the basis of 124.5 anions for the grain used for the structure analysis is: Ba5.05[(Ca8.99Sr0.96Fe2+0.42Na0.10)∑10.47(Ce3.46La1.54Nd1.20Pr0.30Sm0.26Dy0.41Gd0.32Th0.39U4+0.17)∑8.03Y3.53](Ti12.31Nb5.30)∑17.61(SiO4)4.65(PO4)3.12 (BO3)8.89O22.16(OH)38.21F4.89(H2O)1.5. The simplified formula is Ba5(Ca,REE,Y)22(Ti,Nb)18 (SiO4)4[(PO4),(SiO4)]4 (BO3)9O21[(OH),F]43(H2O)1.5. The compatibility index 0.003 (from calculated density) and -0.009 (from measured density). The type material was deposited in the Fersman Mineralogical Museum, Russian Academy of Sciences, Moscow, Russia. читать далее...
Orlovite is a new mineral of the mica group, the titanium analogue of polylithionite. It was discovered in highly quartz rocks in association with pectolite, baratovite, faizievite, aegirine, polylithionite, leucosphenite, fluorite and other minerals in a moraine of the Darai-Pioz glacier (Tajikistan). The mineral is colourless with a glassy to pearly luster. It occurs in flaky aggregates up to 2 cm in size. Cleavage is perfect along (001). Mohs hardness is 2–3. Density (measured) Dm = 2.91(2) g/cm3, density (calculated) Dc = 2.914 g/cm3. The mineral is optically negative, biaxial, np = 1.600, nm = 1.620, ng = 1.625, all ± 0.002, 2Vm = -52(2)°, 2Vc = -52.6°. Orlovite is monoclinic, С2, a = 5.199(3)Å; b = 9.068(7)Å; c = 10.070(4)Å; a = 90°, b = 99.35 (2)°, g = 90°, V = 468.4(4)Å3 , Z = 2. The strongest X-ray lines [(d, Å), (I, %), (hkl)]: 9.96 (40) (001), 4.48 (67) (002), 3.87 (40) (111), 3.33 (100) (-121), 2.860 (35) (-113), 2.600 (28) (130), 2.570 (30) (-131), 2.400 (31) (014), 1.507 (20) (-206). IR – spectra (the strongest absorption bands) are as follows: 3600, 1130, 1087, 985, 961, 878, 776, 721, 669, 613, 567, 530, 512, 458, 405 cm-1. Chemical composition (microprobe, Li2O, Rb2O – ICP OES, H2O – SIMS, wt.%): SiO2 – 58.31, TiO2 – 18.05, Nb2O5 – 0.50, Al2O3 – 0.22, FeO – 0.40, MnO – 0.03, K2O – 11.13, Cs2O – 0.24, Li2O – 7.25, Rb2O – 0.69, H2O – 0.21, F – 4.35, -O=F2 – -1.83, total – 99.55. The empirical formula of orlovite is (K0.97Rb0.03Cs0.01)1.01Li2.00(Ti0.93Nb0.02Fe0.02Al0.02)0.99Si4O11.04(F0.94OH0.10)1.04. Simplified formula KLi2TiSi4O10(ОF). The mineral is named to honor the well-known Russian mineralogist, doctor of mineralogy Yury Leonidivich Orlov (1926–1980), Director (1976–1980) of the A.E. Fersman Mineralogical museum, RAS, specialist in the mineralogy of diamonds and gem stones, and author of more than 50 works including the classical monographs “Mineralogy of Diamond” and “Morphology of Diamond”. читать далее...
Krinov D.I., Azarova Y.V., Struzhkov S.F., Natalenko M.V., Radchenko Y.I. On the Discovery of Rooseveltite, Preisingerite, Troegerite, and Zeunerite In Bi-As-Cu-U-mineralization from the Oranzhevoye Ore Field, Verkhne-Kalganinsky Massif, Magadan Region, Russia, p. 20 - 24
New data on bismuth, arsenic, uranium and copper minerals (rooseveltite, preisingerite, zeunerite, and tröegerite) obtained with the help of an optical microscope and scanning electron microscope equipped with a Link detector are represented in the article. The minerals were established within Bi-As-Cu-U-mineralization at the Oranzhevoye ore field of the Verkhne-Kalganinsky massif in sulfide-quartz, arsenopyrite-quartz and sulfide-quartz-chlorite veinlets that intersect andesites. The following secondary minerals: scorodite, rooseveltite and preisingerite replace arsenopyrite, bismuthinite, tetradymite, and native bismuth. Uranium minerals – zeunerite and tröegerite – also associate with these minerals. Rooseveltite and preisingerite are established in Russia for the first time. Character of occurrence of rooseveltite and preisingerite indicates that they formed during low-temperature metasomatic (hydrothermal) processes. The established association – arsenopyrite, pyrrhotite, chalkopyrite, and minerals of bismuth (bismuthinite and native bismuth, rooseveltite and preisingerite), tellurium (tetradymite), tin (stannite), gold and silver (tellurides, akanthite, native silver) – allowed to attribute this mineralization to the goldpolysulfide-quartz formation. читать далее...
Mannardite Ba(H2O)(Ti6V2)O16 is found in carbonaceous-siliceous schists of the Karatau Ridge (areas Balacauskandyk and Kurumsak), Kazakhstan, and in the Kara-Chagyr and Kara-Tangi, Southern Kyrgyzstan. At Kara-Tangi, it is present as rare grains 10 micron or less in size in assemblages with quarts, pyrite, chalcopyrite, sphalerite, fluorapatite, nickelalumite, and kyrgyzstanite. At Kara-Chagyr, mannardite occurs as small grains under 10 micron in size in quartz veinlets with pyrite, Ce-phosphate, Ba-V-bearing muscovite, nickelalumite, and ankinovichite. In the Balacauskandyk and Kurumsak areas, it forms grains up to 50 micron and aggregates up to 100 micron and larger in size being present in quartz veinlets with Ba-V-bearing muscovite, chernykhite (Kurumsak), V-bearing rutile, Nd, La, and Y phosphates, barite, and hematite. Mannardite from Balasauskandyk is studied in most detail. The mineral has black colour, deep brown in thin scales, and metallic luster. Micro-hardness measurements (from 5 repeated tests) are averaged at 628 kg/mm2 . Density is determined at 4.34(3) g/cm3, by measurement and 4.40 g/cm3 by calculation. Mannardite is anisotropic in reflected light, showing dark-gray color. Unit cell parameters are: а = 14.37(1), c = 5.922(6)Å, V = 1223(2)Å3. Intensive X-ray powder diffraction peaks are as follows: (d, Å; I; hkl): 3.590(4)(400); 3.211(10)(420); 2.844(3)(112); 2.476(7)(312); 2.276(4)(620); 2.227(5)(332); 1.892(5)(352); 1.690(4)(660); 1.592(5)(732). Chemical composition (average by 19 microprobe analyses, wt.%): BaO 20.58; TiO2 58.10; V2O3 18.07; Cr2O3 0.40; H2O(calc.) 1.98; Total 99.13. Empirical formula: Ba1.10(Ti5.94V+31.97 Cr0.04)O16·0.90H2O. Mannardite from Kara-Tangi contains up to 2.4 wt.% of Cr2O3. Along with micas and sulvanite, mannardite is one of early concentrators of vanadium in these rocks. The majority of mannardite is associated with netted quartz veins, which belong to the type of alpine veins. This article discusses the mechanism of formation of these veins during the regional metamorphism of sediments. читать далее...
The new results of the mineralogical study of the Lebedinoe deposit are discussed. In addition to Zn-bearing tetrahedrite (sandbergerite), tetrahedrite-tennantite, and tennantite (Nenasheva et al., 2010), Te-bearing fahlores (goldfieldite-tennantite-tetrahedrite, goldfieldite-tennantite, and Te-bearing tennantite-tetrahedrite), tetrahedrite with significant Ag, and anisotropic tetrahedrite-tennantitewere identified. These minerals were found in varied assemblages, whose mineral composition indicate the conditions of ore formation: the composition of mineral-forming fluid, temperature, and pH value. The chalcocite polysomatic series minerals, digenite, anilite, spionkopite, and yarrowite, used as geothermometer were discovered in the ores. читать далее...
The paper describes mineral assemblages and genesis of mayakite and palladoarsenide in magmatic magnetitepentlandite-chalcopyrite ores of the lower horizons of the Mayak Mine (Talnakh Deposit, Norilsk Ore Field). The mayakite studied here contained up to 1.5 wt.% Pt, whereas palladoarsenide contained up to 3 wt.% Cu and up to 2 wt.% Ni that substitute Pd. Microprobe analyses – 9 for mayakite and 4 for palladoarsenide – are presented in the paper. Palladoarsenide forms linear and branching metasomatic veinlets in mayakite and incomplete pseudomorphs after fine mayakite grains. Palladoarsenide is present at the locations where the ores are tectonized and have veinlets and metasomes of chlorite, carbonates, serpentine, anhydrite, makinawite, and magnetite. In these ore formations, ferroaugite is almost completed replaced by chlorite, carbonates, serpentine, and smectites. Possibly, palladoarsenide originated from the epigenetic processes of low-grade metamorphism (zeolite and prehnite-pumpellyite facies), which are widely abundant in the northwest of the East Siberian Plantform, where the Norilsk Ore Field is located. читать далее...
Mineralogy of wood tin from the Dzhalinda deposit located in the Khingan-Olonoy tin district has been studied. The wood tin is reniform aggregates up to 5 cm in size of concentric zoned cassiterite. Significant later quartz filling tiny fractures in cassiterite layers is close intergrown with cassiterite. Microinclusions of dzhalindite were indetifued in wood tin; acanthite, preisingerite (?), native bismuth and thorium-bearing monazitegroup minerals were found at the deposit for the first time. читать далее...
Glubostrovskoye occurrence is a granite pegmatite with large plates of masutomilite and Li-containing muscovite. Topaz, beryl, manganocolumbite, cassiterite, monazite-(Се), microlite and other accessory minerals also occure there. The structure of the pegmatite is characterized and the data on the morphology and chemical composition of minerals are resulted. The following concentrations of elements are determined in violet and pinkish-violet ferroan masutomilite (crystals are up to 5–20 сm in size) (wt.%): MnO 5.85; Li2O 3.98; Rb2O 1.67. Late pinkish beryl is enriched with rare alkalis, monazite-(Ce) – with samarium, zircon – with hafnium. In microlite we have found partial pseudomorphoses of parabariomicrolite on it. These pseudomorphoses contain the following elements (wt.%): BaO 10.10; UO2 4.98; Ta2O5 73.60; Nb2O5 5.49; SnO2 2.74. It is the first finding in the Urals and in Russia. читать далее...
The review of published and new own data of simple uranium oxides revealed that the formation of five simple oxides is probable: nasturan, sooty pitchblende, uraninite, uranothorianite, and cerianite. Among simple oxides, nasturan, sooty pitchblende, and uraninite are the most abundant in ores varied in genesis and mineralogy. Uranothorianite or thorium uraninite (aldanite) is occasional in the ores, while cerianite is believed in U-P deposits of Northern Kazakhstan. Hydrated nasturan is the most abundant among three uranium (IV+VI) hydroxides in uranium ores. Insignificant ianthinite was found in few deposits, whereas cleusonite was indentified only in one deposit. Simple uranyl hydroxides, schoepite, metaschoepite, and paraschoepite, are widespread in the oxidized ores of the near-surface part of the Schinkolobwe deposit. They are less frequent at the deeper levels and other deposits. Studtite and metastudtite are of insignificant industrial importance, but are of great interest to establish genesis of mineral assemblages in which they are observed, because they are typical of strongly oxidized conditions of formation of mineral assemblages and ores. The X-ray amorphous urhite associated with hydrated nasturan and the X-ray amorphous hydrated matter containing ferric iron and U6+ described for the first time at the Lastochka deposit, Khabarovsk krai, Russia are sufficiently abundant uranyl hydroxides in the oxidized uranium ores. Significant complex uranyl hydroxides with interlayer K, Na, Ca, Ba, Cu, Pb, and Bi were found basically at a few deposits: Schinkolobwe, Margnac, Wölsendorf, Sernyi, and Tulukuevo, and are less frequent at the other deposits, where quite large monomineralic segregations of nasturan and crystals of uraninite were identified. In the other cases, uranium is leached from the oxidizing zone down to background, or richer oxidized ores are formed (Sernyi, Rössing, Shakoptar, and Pap deposits). These features of oxidized uranium ores are theoretically and economically important. читать далее...
Crystal Chemistry, Minerals as Prototypes of New Materials, Physical and Chemical Properties of Minerals
In order to understand the conditions of formation of cubanite СuFe2S3, talnakhite Cu9Fe8S16, mooihoekite Cu9Fe9S16 and haycockite Cu4Fe5S8 in magmatic Cu-Fe ores of the Norilsk type the method of melt cooling from 1150–1100°C up to room temperature and subsequent annealing at 600 and 800°C phase associations of the central part of Cu-Fe-S system have been synthesized: 50 at.% of S, Cu/Fe = 1.22–0.25, 47 at.% S, Cu/Fe = 1.12–0.63 and 45 at.% S, Cu/Fe = 1.44–0.69. According to the received results, cubic cubanite enriched in copper (Cu/Fe і 0.5) crystallizes in associations with tetragonal chalcopyrite Cu1-xFe1+xS2 and cubic talnakhite. The new data concerning steady phase equillibriums of mooihoekite with bornite Cu5FeS4 and cubic pc phase of the haycockite composition with cubic cubanite enriched in iron (Cu/Fe Ј 0.5) bornite and pyrrhotite Fe1-xS are received. читать далее...
Mineralogical Museums and Collections
A brief history of the Peterhof Cutting Factory is documented, the art pieces mastered at the factory and kept in the Fersman Mineralogical Museum are described. читать далее...
The first master catalogues of the Mineral Cabinet of the Kunstkamera which became the fundamentals of the collection of the Mineralogical museum of Academy of Science are reviewed in this article. These are: the first printed Mineral Catalogue from 1745 (compiled by I.G. Gmelin, I. Amman and M.V. Lomonosov) and handwritten catalogues from the Mineralogical museum archive – by J.G. Lehmann (1766) and J.G. Georgi (1789). Also the Mineralogical museum archive preserved the Catalogue of the Gottwald’s Museum whose collection was acquired by Peter the Great for the Kunstkamera in 1714. читать далее...
According to the descriptions by M.V. Lomonosov, in the Mineral catalogue of the Kunstkamera 1745, there were identified several specimens, kept in the Fersman Mineralogical museum RAS: five slabs of marble Florentine mosaics with pictures of Tuscany landscapes and, less corresponded, seven slabs of Florentine ruin marble, which are the earliest items in the collection of the Mineralogical museum and the first and the only samples attributed according to the Mineral catalogue of the Kunstkamera 1745. The date of acquisition of Dr. Gottwald’s collection to the Mineral Cabinet of the Kunstkamera – the present Fersman Mineralogical museum RAS – is re-estima ted and refined. читать далее...
Exhibitions «Wonders in the stone» which are already carried out almost 50 years are one of the most appreciable initiatives of the Society of amateurs attached to the Moscow Society of Naturalists (MOIP). In 2011 the 45-th exhibition «Wonders in the stone» having a subtitle «Remarkable minerals of the Russia» has been organized in the Fersman Mineralogical museum belonging to the Russian Academy of Sciences. читать далее...
In 2009–2010 to the main collection of the Fersman Mineralogical museum RAS were acquired 840 specimens of minerals, meteorites, tectites, stone artpieces etc. The systematic collection was replenished with 339 mineral species including 90 new mineral species for the Museum, 42 of which are represented by the type specimens (holotypes, co-types and their fragments). 5 of them were discovered with help of the Museum researchers. Two species were discovered in the specimens from the Museum collection. Geography of acquisitions includes 62 countries and also extraterrestrial objects. More than 77% of all the acquisitions were donated by 105 private persons and 2 organizations. Museum collecting resulted in slightly over 12% of acquisitions; 6,5% arrived from an exchange and 3% was purchased. Less than 2% is represented by another types of acquisitions. In this paper, the new acquisitions are described by mineral species, geography, acquisition type and donors. The list of the new acquisitions is given. читать далее...
In 2011 we have celebrated 85th Anniversary of Yuriy Leonidovich Orlov. He was a talented Russian mineralogist and field researcher, expert in mineralogy of diamond. Being an exceptional expert of precious stones, he was a lead expert of the Ministry of Finance of the USSR. Yuriy L. Orlov contributed a lot in the Museum development. читать далее...
Morphologically rare skeletal crystals of calcite from karst cavities in limestones of the Kaluga region are described. The new data of the morphology and the internal structure of skeletal crystals were obtained using a scanning electron microscope and optical methods. Acicular individuals evolves to “tower” and “bastion” aggregates of skeletal crystals; the formation model of these aggregates is proposed. The aggregates studied here are of various shades of yellow, and less frequent pink, blue, and green. Any shade changes to dirty-white if colored specimens are stored in low-humidity environment. The relationship between calcite colour and adsorbed water is suggested. The karst system, where skeletal crystals have been formed is of interest. Daily (5–10°С) and seasonal (30–40°С) temperature variations have been recorded, The observed significant seasonal fluctuations of the system debit are not typical of karst. It is suggested that these features account for by unusual active ventilation of this karst system. читать далее...
The mineral assemblages and conditions of formation of bilibinskite are reported. The color photos, without which this unique Au-rich mineral is difficult to be determined, are shown for the first time. The photos illustrate extremely strong bireflectance and anisotropy of bilibinskite. The chemical composition of bilibinskite from the cementation zone of the Aginskoe and Ozernovskoe, Kamchatka, and Pionerskoe, Sayan Mountains gold-telluride deposits is refined. The chemical composition of the bilibinskite from the Aginskoe and Ozernovskoe deposits is close to Au5Cu3(Te,Pb)5; while that of Pionerskoe is close to Au6Cu2(Te,Pb,Sb)5; generalized formula (Au56Cu32)8(Te,Pb,Sb)5. Bilibinskite in the oxidation zone is the direct prospecting guide to rich endogenic goldtelluride mineralization. читать далее...
Kimberlites of numerous pre-trappean pipes and dikes of East Siberia platform have significant amount of lizardite serpentine, which associates with calcite, dolomite, amakinite or brusite, magnetite, goethite, pyrite, quartz, chalcedony, amethyst, smectites, hydrotalcite group minerals, celestine, stroncianite and some ore minerals. This paragenesis witnesses low grade metamorphism of zeolite facies which altered the rocks at various degree. Processes of regional low grade metamorphism usually occur in conditions of high oxidation potential causing formation of hematite and magnetite in metakimberlites. Patches of fresh rock can be found in Udachnaya-Vostochnaya pipe and in some places there is no goethite or magnetite present in very altered rocks. Pyrrhotite and pentlandite occur in abundance instead. Pyrrhotite and pentlandite of the studied samples are closely associated with Cl-containing lizardite and magnesian hibbingite (Fe2+1.55Mg0.42Mn2+0.03)2.00(OH2.88Cl0.12)3.00Cl1.00. Presence of hibbingite confirms our assumption that kimberlite were altered with fluids rich in chlorine. The source of them was chloride brines derived from evaporates that occur in the carbonate-terrigenous sequence hosting Udachnaya-Vostochnaya pipe. Pyrrhotite composition has high iron content and is very close to FeS, thus the mineral is not magnetic. We need to note that studied metakimberlites do not contain magnetic minerals. Average pentlandite composition corresponds to the formula (Ni4.0Fe4.5Co0.5)9.0S8.0 with Ni/Co ratio close to the one in primary kimberlite and kimberlitic olivine and is in range from 7.7 to 9.9. Apparently, olivine was the source of Fe, Ni and Co, and sulphur derived from an hydrite-bearing carbonate-terrigenous early Paleozoic host rocks, saturated with bitumen, which often contain sulfur compounds. читать далее...