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Thalhammerite, Pd9ag2bi2s4, a New Mineral from the Talnakh and Oktyabrsk Deposits, Noril’Sk Region, Russia

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Thalhammerite, Pd9ag2bi2s4, a New Mineral from the Talnakh and Oktyabrsk Deposits, Noril’Sk Region, Russia minerals Article Thalhammerite, Pd9Ag2Bi2S4, a New Mineral from the Talnakh and Oktyabrsk Deposits, Noril’sk Region, Russia Anna Vymazalová 1,*, František Laufek 1, Sergey F. Sluzhenikin 2, Vladimir V. Kozlov 3, Chris J. Stanley 4, Jakub Plášil 5, Federica Zaccarini 6, Giorgio Garuti 6 and Ronald Bakker 6 1 Czech Geological Survey, Geologická 6, 152 00 Prague 5, Czech Republic; [email protected] 2 Institute of Geology of Ore Deposits, Mineralogy, Petrography and Geochemistry RAS, Staromonetnyi per. 12, Moscow 119017, Russia; [email protected] 3 Oxford Instruments (Moscow Office), 26 Denisovskii Pereulok, Moscow 105005, Russia; [email protected] 4 Department of Earth Sciences, Natural History Museum, London SW7 5BD, UK; [email protected] 5 Institute of Physics, AS CR v.v.i. Na Slovance 2, 182 21 Prague 8, Czech Republic; [email protected] 6 Department of Applied Geosciences and Geophysics, University of Leoben, Peter Tunner Str. 5, A 8700 Leoben, Austria; [email protected] (F.Z.); [email protected] (G.G.); [email protected] (R.B.) * Correspondence: [email protected]; Tel.: +420-251-085-228 Received: 19 July 2018; Accepted: 3 August 2018; Published: 8 August 2018 Abstract: Thalhammerite, Pd9Ag2Bi2S4, is a new sulphide discovered in galena-pyrite-chalcopyrite and millerite-bornite-chalcopyrite vein-disseminated ores from the Komsomolsky mine of the Talnakh and Oktyabrsk deposits, Noril’sk region, Russia. It forms tiny inclusions (from a few µm up to about 40–50 µm) intergrown in galena, chalcopyrite, and also in bornite. Thalhammerite is brittle and has a metallic lustre. In plane-polarized light, thalhammerite is light yellow with weak bireflectance, weak pleochroism, in shades of slightly yellowish brown and weak anisotropy; it exhibits no internal reflections. Reflectance values of thalhammerite in air (R1,R2 in %) are: 41.9/43.0 at 470 nm, 43.9/45.1 at 546 nm, 44.9/46.1 at 589 nm, and 46.3/47.5 at 650 nm. Three spot analyses of thalhammerite give an average composition: Pd 52.61, Bi 22.21, Pb 3.92, Ag 14.37, S 7.69, and Se 0.10, total 100.90 wt %, corresponding to the empirical formula Pd8.46Ag2.28(Bi1.82Pb0.32)S2.14(S4.10Se0.02)S4.12 based on 17 atoms; the average of five analyses on synthetic thalhammerite is: Pd 55.10, Bi 24.99, Ag 12.75, and S 7.46, total 100.30 wt %, corresponding to Pd8.91Ag2.03Bi2.06S4.00. The density, calculated on the basis of the empirical formula, is 9.72 g/cm3. The mineral is tetragonal, space group I4/mmm, with a 8.0266(2), c 9.1531(2) Å, V 589.70(2) Å3 and Z = 2. The crystal structure was solved and refined from the single-crystal X-ray-diffraction data of synthetic Pd9Ag2Bi2S4. Thalhammerite has no exact structural analogues known in the mineral system; chemically, it is close to coldwellite (Pd3Ag2S) and kravtsovite (PdAg2S). The strongest lines in the X-ray powder diffraction pattern of synthetic thalhammerite [d in Å (I)(hkl)] are: 3.3428(24)(211), 2.8393(46)(220), 2.5685(21)(301), 2.4122(100)(222), 2.3245(61)(123), 2.2873(48)(004), 2.2201(29)(132), 2.0072(40)(400), 1.7481(23)(332), and 1.5085(30)(404). The mineral honours Associate Professor Oskar Thalhammer of the University of Leoben, Austria. Keywords: thalhammerite; platinum-group mineral; Pd9Ag2Bi2S4 phase; reflectance data; X-ray-diffraction data; crystal structure; Komsomolsky mine; Talnakh deposit; Noril’sk region; Russia 1. Introduction Thalhammerite, ideally Pd9Ag2Bi2S4, was observed in the same holotype specimen as kravtsovite, PdAg2S[1], and vymazalováite, Pd3Bi2S2 [2]. The type sample (polished section) comes from Minerals 2018, 8, 339; doi:10.3390/min8080339 www.mdpi.com/journal/minerals Minerals 2018, 8, 339 2 of 13 vein-disseminated pyrite-chalcopyrite-galena ore from the Komsomolsky mine in the Talnakh deposit of the Noril’sk district, Russia. The sample was found at coordinates: 69◦3002000 N and 88◦27Minerals01700 E. 2018 The, 8, x mineralization is characterized by lack of Ni minerals and high galena2 of content 14 and Pt-Pd-Ag bearing minerals in an association of pyrite and chalcopyrite. The host rocks of disseminated pyrite-chalcopyrite-galena ore from the Komsomolsky mine in the Talnakh deposit of pyrite-chalcopyrite-galena ore are diopside-hydrogrosssular-serpentine metasomatites developed the Noril’sk district, Russia. The sample was found at coordinates: 69°30′20″ N and 88°27′17″ E. The in diopside-monticellitemineralization is characterized skarns belowby lack theof Ni lower minerals exocontact and high galena of the content Talnakh and intrusion Pt-Pd-Ag (thebearing eastern partminerals of the Komsomolsky in an association mine).of pyrite and Thalhammerite, chalcopyrite. The in host pyrite-chalcopyrite-galena rocks of pyrite-chalcopyrite-galena ores, occurs ore in associationare diopside-hydrogrosssular-serpentine with cooperite, braggite, vysotskite, metasomatites stibiopalladinite, developed telargpalite, in diopside-monticellite sobolevskite, skarns kotulskite, sopcheite,below insizwaite,the lower exocontact kravtsovite, of the vymazalov Talnakh áintrusioite, Au-Agn (the alloys, eastern and part Ag-bearing of the Komsomolsky sulphides, mine). selenides, sulphoselenides,Thalhammerite, and in tellurosulphoselenides.pyrite-chalcopyrite-galena Theores, mineral occurs in was association also observed with cooperite, in vein-disseminated braggite, millerite-bornite-chalcopyritevysotskite, stibiopalladinite, ore telarg frompalite, the sobolevskite, Talnakh and kotulskite, Oktyabrsk sopcheite, deposits insizwaite, of the Noril’sk kravtsovite, region [3]. The hostvymazalováite, rocks of millerite-bornite-chalcopyrite Au-Ag alloys, and Ag-bearing ore are su pyroxene-hornfelslphides, selenides, at thesulphoselenides, lower exocontact and of the Kharaelakhtellurosulphoselenides. intrusion (the westernThe mineral part ofwas the also Komsomolsky observed in mine).vein-disseminated In millerite-bornite-chalcopyrite millerite-bornite- chalcopyrite ore from the Talnakh and Oktyabrsk deposits of the Noril’sk region [3]. The host rocks ore, thalhammerite occurs in association with kotulskite, telargpalite, laflammeite, and Au-Ag alloys. of millerite-bornite-chalcopyrite ore are pyroxene-hornfels at the lower exocontact of the Kharaelakh Theintrusion mineral (the likelywestern formed part of underthe Komsomolsky the same conditions mine). In millerite-bornite-chalcopyrite as kravtsovite and vymazalov ore, áite, ◦ withthalhammerite decreasing temperature occurs in association [3], most with likely kotulskite, below telargpalite, 400 C. Thalhammerite laflammeite, and was Au-Ag also alloys. observed, in intergrowthsThe withmineral sobolevskite, likely formed in PGEunder ores the fromsame theconditions Fedorov-Pana as kravtsovite Layered and Intrusive vymazalováite, Complex, with Russia (V.V.decreasing Subbotin—per. temperature communication). [3], most likely Furthermore, below 400 °C. theThalhammerite occurrence was of unknownalso observed, phases in intergrowths corresponding to Pb-with and sobolevskite, Tl-analogues in PGE of thalhammerite ores from the Fedoro from thev-Pana Fedorov-Pana Layered Intrusive Layered Complex, Intrusive Russia Complex (V.V. has beenSubbotin—per. reported [4]. communication). Furthermore, the occurrence of unknown phases corresponding to BothPb- and the Tl-analogues mineral and of namethalhammerite were approved from the by Fedorov-Pana the Commission Layered on Intrusive New Minerals, Complex Nomenclature has been and Classificationreported [4]. of the International Mineralogical Association (IMA No 2017-111). The mineral Both the mineral and name were approved by the Commission on New Minerals, Nomenclature name is for Dr. Oskar Thalhammer (b. 1956) Associate Professor at the University of Leoben, Austria and Classification of the International Mineralogical Association (IMA No 2017-111). The mineral for hisname contributions is for Dr. Oskar to the Thalhammer ore mineralogy (b. 1956) and Associat minerale Professor deposits at of the platinum University group of Leoben, elements. Austria The type specimenfor his is contributions deposited at to the the Department ore mineralogy of Earthand mi Sciencesneral deposits of the of Natural platinum History group Museum,elements. The London, UK, cataloguetype specimen no. BMis deposited 2016, 150. at the Department of Earth Sciences of the Natural History Museum, London, UK, catalogue no. BM 2016, 150. 2. Appearance, and Physical and Optical Properties 2. Appearance, and Physical and Optical Properties Thalhammerite forms very small inclusions (from a few µm up to about 40–50 µm) in galena, chalcopyriteThalhammerite (Figure1), andforms also very in small bornite. inclusions (from a few μm up to about 40–50 μm) in galena, chalcopyrite (Figure 1), and also in bornite. (a) Figure 1. Cont. Minerals 2018, 8, 339 3 of 13 Minerals 2018, 8, x 3 of 14 (b) FigureFigure 1. Digital 1. Digital image image in in reflected reflected plane planepolarized polarized light showing showing inclusions inclusions of thalhammerite of thalhammerite in in galenagalena (gn) (gn) in association in association with with (a )(a chalcopyrite) chalcopyrite (ccp) (ccp) andand ( (bb)) vymazalováite vymazalováite (vym). (vym). The mineral occurs in aggregates (100–200 μm in size) formed by intergrowths of telargpalite, Thebraggite, mineral vysotskite, occurs sopcheite, in aggregates stibiopalladinite, (100–200 µ msobolevskite, in size) formed moncheite, by intergrowths kotulskite, malyshevite, of telargpalite, braggite,insizwaite, vysotskite,
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