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An investigation of sample 41647 from the Platinum Placer of Ugol'nyi Ruchei, Norilsk Cu–Ni deposit, Russia, stored in the systematic collection of the Fersman Mineralogical Museum, revealed that it contained a mineral that can be identified as the original stannopalladinite described in 1947. As the literature information on the latter is controversial, the mineral was re-investigated using modern analytical techniques. Stannopalladinite occurs as spherical and ovoid-shaped grains up to 0.08 mm, closely intergrown with tetraferroplatinum as part of flattened, prismatic crystals up to 6 mm long. The micro-indentation hardness of stannopalladinite (VHN, 30 g load) is 244 kg/mm2 (range 233–266, n = 4), corresponding to a Mohs hardness of 4. The calculated density is 9.781 g/cm3. In reflected light, stannopalladinite is pale pink. The bireflectance is noticeable only in oil immersion. In crossed nicols the mineral exhibits strong anisotropy with colour effects changing from reddish purple to greyish blue and polysynthetic twinning of grains. The reflectance curves show distinct anomalous dispersion. The chemical composition (wt.%, electron microprobe data, mean of 11 analyses) is: Cu 8.48, Pd 61.21, Pt 0.89, Sn 25.87, Pb 3.70, total 100.15. The empirical formula calculated on the basis of 4 atoms per formula unit is (Pd2.42Cu0.56Pt0.02)Σ3.00(Sn0.92Pb0.08)Σ1.00. The ideal chemical formula of stannopalladinite is therefore proposed as (Pd,Cu)3Sn instead of Pd3Sn2 used in the official IMA List of Minerals. The strongest powder X-ray diffraction lines are [ d obs, Å (I , %) (hkl) ]: 2.292 (42) (231), 2.166 (100) (331), 2.034 (10) (710), 1.916 (15) (141) and 1.851 (15) (630). The powder X-ray data are indexed in the orthorhombic unit cell with a = 14.634(2), b = 8.5253(6), c = 4.5946(3) Å and V = 573.24(7) Å3 (Z = 8). Stannopalladinite can be reliably identified among all other minerals belonging to the binary Pd–Sn and ternary Pd–Cu–Sn systems by a combination of chemical, optical and X-ray data. [ABSTRACT FROM AUTHOR]

Fluorpyromorphite, ideally Pb5(PO4)3F, a new apatite-group member, an F-dominant analog of pyromorphite and hydroxylpyromorphite. It is a supergene mineral found at two localities: Sukhovyaz Mountain, Ufaley District, Southern Urals (holotype) and Mountain 1004, Tolbachik volcano, Kamchatka (co-type), both in Russia. At Sukhovyaz, fluorpyromorphite forms anhedral grains up to 0.2 mm across (usually much smaller), filling cavities in quartz and sometimes partially replacing fluorapatite. Associated supergene minerals include pyromorphite, hydroxylpyromorphite, fluorphosphohedyphane, mimetite, and nickeltsumcorite. At Tolbachik, fluorpyromorphite occurs in the oxidation zone of paleo-fumarolic deposits in close association with pyromorphite, fluorphosphohedyphane, wulfenite, cerussite, munakataite, vanadinite, chrysocolla, and opal. It forms crude long-prismatic to acicular crystals up to 0.1 mm long and up to 5 μm thick combined in bunches and spherulites up to 0.2 mm. Fluorpyromorphite is colorless (Sukhovyaz) or yellow (Tolbachik), translucent to transparent and has a vitreous luster. It is brittle, with an uneven fracture and poor cleavage on (001). The calculated density values are 7.382 (holotype) and 6.831 (cotype) g/cm³. Fluorpyromorphite is optically uniaxial (-). In reflected light, it is light-grey, weakly anisotropic. The reflectance values (Rmin/Rmax, %) are: 15.8/16.6 (470 nm), 16.2/17.2 (546 nm), 15.9/16.9 (589 nm), 15.4/16.2 (650 nm). The chemical composition is (electron microprobe, wt. %; holotype/co-type): CaO 0.10/3.16, SrO 0.17/0.00, PbO 83.51/77.39, P2O5 16.13/16.35, CrO3 0.00/0.49, SeO3 0.00/0.98, F 1.00/1.35, Cl 0.29/0.40, H2Ocalc 0.13/0.00, -O=(F,Cl) -0.49/-0.66, total 100.84/99.46. The empirical formulae based on 13 anions (O + F + Cl + OH) pfu are Pb4.95Ca0.02Sr0.02P3.00O12F0.70(OH)0.19Cl0.11 (holotype) and Pb4.26Ca0.69P2.83Se6+ 0.09Cr6+0.06 O11.99F0.87Cl0.14 (co-type). Fluorpyromorphite is hexagonal, space group P63m, unit-cell parameters (from powder X-ray diffraction data; holotype / co-type) are: a = 9.779(5) / 9.732(1), c = 7.241(9) / 7.242(1) Å, V = 599.6(7) / 594.0(2) Å3, and Z = 2. The crystal structure was refined using the Rietveld method to Rp= 0.1764 (holotype). Fluorpyromorphite is isostructural with other members of the apatite group, a subdivision of the apatite supergroup. [ABSTRACT FROM AUTHOR]

Kaznakhtite, ideally Ni6Co3+2(CO3)(OH)16⋅4H2O, is a new member of the hydrotalcite group within the hydrotalcite supergroup. The mineral was discovered at the Kaznakhtinskiy ultrabasic massif, Altai Republic, SW Siberia, Russia. It occurs as powdery aggregates forming flattened lenses up to 1.5 × 0.5 cm and veinlets up to 1 cm long and up to 1 mm thick in aggregates of chrysotile, lizardite, stichtite and dolomite. Other associated minerals include brucite, chromite, heazlewoodite, manganochromite, magnetite and magnesioferrite. Kaznakhtite aggregates are composed of tiny platy grains up to 0.01 mm across. Kaznakhtite is light green and translucent in aggregates. It has an earthy lustre and white streak. Cleavage is micaceous on {001}. Dcalc = 2.864 g cm–3. The mineral is optically uniaxial (–) with ɛ = 1.657(3) and ω = 1.676(3), and weakly pleochroic in greenish hues, ω > ɛ. Chemical composition (wt.%, electron microprobe, Co valence state determined by XANES spectroscopy, CO2 and H2O calculated by stoichiometry) is: MgO 2.15, NiO 47.40, ZnO 0.22, Al2O3 0.16, Cr2O3 0.98, Co2O3 17.42, Cl 0.63, CO2 5.05, H2O 24.60, –O=Cl –0.14, total 98.47. The empirical formula calculated based on the sum of all metal cations = 8 apfu is (Ni5.54Mg0.47Zn0.02)Σ6.03(Co3+1.83Cr0.11Al0.03)Σ1.97C1.00O2.99(OH)15.84Cl0.16⋅4H2O. Infrared spectroscopy confirmed the presence of CO32– anions, OH– groups and H2O molecules. The crystal structure was refined by the Rietveld method with RB = 0.19%. Kaznakhtite is trigonal, space group R͞3m, a = 3.0515 (3), c = 23.180 (3) Å, V = 186.93 (4) Å3 and Z = 3/8. The strongest lines of the powder X-ray diffraction pattern [d, Å (I, %) (hkl)] are: 7.72 (100) (003); 3.863 (24) (006); 2.630 (4) (101); 2.576 (10) (012); 2.294 (6) (015); 1.950 (4) (018); 1.526 (4) (110); and 1.497 (4) (113). Kaznakhtite is a Co3+ analogue of reevesite, Ni6Fe3+2(CO3)(OH)16⋅4H2O. The mineral is named after its type locality. [ABSTRACT FROM AUTHOR]

Gurzhiite, ideally Al(UO2)(SO4)2F⋅10H2O, is a new uranyl sulfate mineral from the Bykogorskoe U deposit, Northern Caucasus, Russia. It occurs as fine-grained aggregates forming veinlets up to 50 cm long in cracks of the brecciated rock. Gurzhiite aggregates are composed of small bladed crystals up to 0.1 mm across. Associated minerals include khademite and quartz. Gurzhiite is pale yellow in crystals, lemon yellow in aggregates, transparent with a vitreous lustre and a white streak. It is brittle and has an irregular fracture. Cleavage is good on {001}. The new mineral exhibits a bright yellow–green fluorescence under both longwave and shortwave UV radiation. Mohs hardness is ~2. Dmeas = 2.52(3) g/cm3 and Dcalc = 2.605 g/cm3. The mineral is biaxial (–) with α = 1.528(3), β = 1.538(2), γ = 1.544(3) (589 nm); 2Vmeas= 80(10)° and 2Vcalc = 75.1°. The empirical formula calculated on the basis of 21(O + F) atoms per formula unit (apfu) is Al0.92Zn0.05Fe3+0.03Na0.03U0.95S2.00O9.85F0.99⋅10.16H2O. Gurzhiite is triclinic, with space group P $\bar{1}$ , a = 7.193(2), b = 11.760(2), c = 11.792(2) Å, α = 67.20(3), β = 107.76(3), γ = 89.99(3)°, V = 867.7(4) Å3 and Z = 2. The five strongest lines of the powder X-ray diffraction pattern [d, Å (I, %)(hkl)] are: 10.24(100)(001); 5.40(14)($\bar{ 1}\bar{1}$ 1); 5.11(54)(002); 3.405(11)($\bar{2}$ 11); and 3.065(11)($\bar{1}\bar{1}$ 3). The crystal structure of gurzhiite is based upon uranyl sulfate chains of the same type as in bobcookite and svornostite. Between the chains are two types of Al-octahedra – Al1(H2O)6 and Al2F2(H2O)4. The entire structure stability is maintained by a complex network of H bonds. The new mineral honours Russian mineralogist and crystallographer Dr. Vladislav V. Gurzhiy in recognition for his contributions to uranium mineralogy and crystallography. [ABSTRACT FROM AUTHOR]

Pokhodyashinite CuTlSb2(Sb1-xTlx)AsS7-x, is a new sulfosalt from the Vorontsovskoe gold deposit, Sverdlovsk Oblast', Northern Urals, Russia. It forms anhedral grains up to 0.1 × 0.05 mm in size in calcite and is associated with major orpiment, pyrite, realgar and minor baryte, clinochlore, As-bearing fluorapatite, harmotome, prehnite, native gold and a rich spectrum of sulfosalts. Pokhodyashinite is black, opaque, and has a metallic luster and a black streak. It is brittle, with an uneven fracture and poor cleavage on {100}. The Vickers hardness (VHN, 20 g load) is 55 kg/mm2, corresponding to a Mohs hardness of 2. The calculated density is 5.169 g/cm3. In reflected light, pokhodyashinite is grayish-white, bireflectance is distinct. In crossed polars, it is strongly anisotropic; rotation tints vary from dark brownish gray to light bluish-gray. No internal reflections are observed. The reflectance values for wavelengths recommended by the Commission on Ore Mineralogy of the IMA are (Rmin/Rmax, %): 28.9/34.6 (470 nm), 27.6/33.4 (546 nm), 26.7/32.4 (589 nm), 26.1/31.1 (650 nm). The empirical formula of pokhodyashinite based on ΣMe = 6 apfu is Cu0.700Ag0.340Tl1.320Pb0.020Sb2.630As0.990S6.625. Pokhodyashinite is monoclinic, space group C2/m, a = 23.431(5), b = 3.996(2), c = 14.070(3) Å, β = 110.23(3)°, V = 1236.1(8) ų and Z = 4. Its structure can be described as wavy slabs of a complex structure based on double-rods of Sb-coordination pyramids and lone-electron-pair interspaces/micelles, separated by wavy interlayers consisting of paired columns of Tl and rods of paired Cu-coordination polyhedra. A small amount of Tl-for-Sb substitution results in partial anion vacancies in one sulfur site. The new mineral is named in honor of Maxim Mikhailovitch Pokhodyashin, a pioneer of mining engineering and smelting works in the Northern Urals of the 18th century. [ABSTRACT FROM AUTHOR]

Three new isostructural minerals, alexkuznetsovite-(La), ideally La2Mn(CO3)(Si2O7), alexkuznetsovite-(Ce) Ce2Mn(CO3)(Si2O7) and biraite-(La) La2Fe2+(CO3)(Si2O7), were discovered in polymineralic nodules from the Mochalin Log REE deposit, South Urals, Russia. The new minerals form anhedral grains up to 0.3 mm × 0.4 mm [alexkuznetsovite-(La)], 0.5 mm × 0.9 mm [alexkuznetsovite-(Ce)] and 0.2 mm × 1.2 mm [biraite-(La)] embedded in granular aggregates consisting of different REE minerals [allanite-(Ce)/-(La), bastnäsite-(Ce)/-(La), fluorbritholite-(Ce), perbøeite-(Ce)/-(La), percleveite-(Ce)/-(La) and törnebohmite-(Ce)/-(La)]. All three new species are brown to dark brown, translucent in thin fragments, with white streak, vitreous lustre and Mohs' hardness of ~5. Dcalc = 4.713 [alexkuznetsovite-(La)], 4.687 [alexkuznetsovite-(Ce)] and 4.682 [biraite-La)] g⋅cm–3. Their empirical formulae, calculated on the basis of 2 Si and 10 O apfu, are: alexkuznetsovite-(La): (La0.98Ce0.89Nd0.10Pr0.05)Σ2.02Mn2+0.50Fe2+0.29Ca0.12Mg0.03(CO3)0.94(HCO3)0.06 (Si2O7); alexkuznetsovite-(Ce): (Ce0.96La0.78Nd0.16Pr0.07)Σ1.97Th0.01Mn2+0.50Fe2+0.33Ca0.14Mg0.02(CO3)0.93(HCO3)0.07(Si2O7); and biraite-(La): (La0.95Ce0.87Nd0.08Pr0.04)Σ1.94Th0.01Ca0.12Fe2+0.44Mn2+0.38Mg0.07(CO3)0.88(HCO3)0.12(Si2O7). The new minerals are monoclinic, P21/c and Z = 4. The unit-cell parameters of alexkuznetsovite-(La)/alexkuznetsovite-(Ce)/biraite-(La) are: a = 6.5642(3)/6.5764(4)/6.5660(10), b = 6.7689(3)/6.7685(4)/6.7666(11), c = 18.7213(10)/18.7493(15)/18.698(3) Å, β = 108.684(6)/108.672(8)/108.952(16)° and V = 788.00(7)/790.66(10)/785.7(2) Å3. The crystal structures are solved from single-crystal X-ray diffraction data; R = 0.0628 [alexkuznetsovite-(La)], 0.0589 [alexkuznetsovite-(Ce)] and 0.1193 [biraite-(La)]. A new biraite group is defined; it includes isostructural biraite-(Ce) and the three new minerals described herein. The rootname alexkuznetsovite is given in honour of the Russian mineral collector Alexey M. Kuznetsov (born 1962) who provided samples in which all three new minerals were found. The Levinson's suffix-modifier -(La) or -(Ce) indicates the predominance of La or Ce among REE in the mineral. Biraite-(La) is named as an analogue of biraite-(Ce) with La prevailing among REE. [ABSTRACT FROM AUTHOR]

Auerbakhite (IMA 2020-047), MnTl2As2S5, is a new sulfosalt from the Vorontsovskoe gold deposit, Sverdlovsk Oblast', Northern Urals, Russia. The new mineral occurs in limestone breccias composed of calcite, dolomite, baryte, clinochlore, fluorapatite and quartz, and cemented by major realgar, orpiment and pyrite. Other minerals directly associating with auerbakhite include alabandite, bernardite, christite, cinnabar, coloradoite, dalnegroite, gillulyite, gold, hutchinsonite, imhofite, lorándite, metacinnabar, philrothite, rebulite, routhierite, sphalerite, and vrbaite. Auerbakhite forms rare and very small short-prismatic crystals and irregular grains which do not exceed 15 × 5 µm. It is transparent, has a bright red color and adamantine luster. Auerbakhite is brittle, with an uneven fracture. Cleavage is not observed. The calculated density is 5.245 g/cm³. In reflected light, auerbakhite is light gray, weakly bireflectant. In crossed polars, it is distinctly anisotropic, in light gray and brown tones, with abundant bright red internal reflections. The empirical formula of auerbakhite is Mn1.04Tl1.97Pb0.02As1.95S5.02 (based on 10 atoms pfu). Prominent features in the Raman spectrum include bands of Mn-S and As-S stretching vibrations and numerous low-frequency bands related to mixed soft modes involving bending and Tl-S stretching vibrations. Auerbakhite is orthorhombic, space group Cmce, a = 15.3280(15) Å, b = 7.662(7)Å, c = 16.6330(14)Å, V = 1953.40(18)ų and Z = 8. The crystal structure of auerbakhite was refined from the single-crystal X-ray diffraction data to R = 0.0723 for 307 observed reflections with Iobs > 3σ(I). Auerbakhite is isostructural to the synthetic phase Tl2MnAs2S5. Its crystal structure consists of complex (001) layers based on a set of MnS4 columns parallel to [010] and are composed of edge-sharing slightly irregular MnS6 octahedra. The columns are connected via Tl1 and are framed by paired AsS3 pyramids with lone electron pairs oriented into interlayer space. Highly irregular Tl(2)S6 coordination polyhedra are situated in interlayers and share ligands with the layers. The new mineral honors Russian mining engineer, manufacturer and mineralogist Alexander Andreevitch Auerbakh whose activities were closely related to Northern Urals. [ABSTRACT FROM AUTHOR]

Luboržákite, ideally Mn2AsSbS5, is a new mineral from the Vorontsovskoe gold deposit, Northern Urals, Russia. It forms long-prismatic crystals up to 70 × 20 μm and anhedral grains of the same size embedded in the matrix of Mn-bearing dolomite and Mn-bearing calcite. Associated minerals include pyrite, orpiment, realgar, stibnite, aktashite, alabandite, boscardinite, chabournéite, coloradoite, clerite, écrinsite, gold, routhierite, sphalerite and twinnite. Luboržákite is black, opaque with metallic lustre and has a black streak. It is brittle and has an uneven fracture. No cleavage and parting have been observed. Mohs hardness is 4–4½. Dcalc = 4.181 g cm–3. In reflected light, luboržákite is tin-white, weakly anisotropic with rotation tints varying from dark grey to grey. The chemical composition of luboržákite is (wt.%; electron microprobe, WDS mode): Mn 21.23, Cu 0.29, Ag 0.56, Pb 1.90, As 15.25, Sb 27.03, S 33.23, total 99.49. The empirical formula based on the sum of all atoms = 9 apfu is Mn1.86Pb0.04Ag0.03Cu0.02As0.98Sb1.07S5.00. The new mineral is monoclinic, space group C2/m with a = 12.5077(6), b = 3.8034(2), c = 16.0517(8) Å, β = 94.190(4)°, V = 761.57(6) Å3 and Z = 4. The crystal structure of luboržákite was solved from the single-crystal X-ray diffraction data to R = 0.0383 for 712 observed reflections with I > 3σ(I). Luboržákite is a new member of the heterochemical isostructural series of 'unit-cell twinned' structures, named the pavonite series. The new mineral honours Lubor Žák, a prominent Czech crystallographer and the professor of the Charles University in Prague, Czech Republic. [ABSTRACT FROM AUTHOR]

The paper opens a series devoted to the mineral diversity of the Mochalin Log rare earth element (REE) deposit, South Urals, Russia. There is a brief outline of the history of studies and geology of the deposit as well as the description of two new isostructural gatelite-group minerals, ferriperbøeite-(La) (CaLa3)(Fe3+Al2Fe2+)[Si2O7][SiO4]3O(OH)2 and perbøeite-(La) (CaLa3)(Al3Fe2+)[Si2O7][SiO4]3O(OH)2. Both minerals occur in polymineralic nodules and are associated with one another and allanite-(Ce), allanite-(La), bastnäsite-(Ce), bastnäsite-(La), ferriallanite-(Ce), ferriallanite-(La), ferriperbøeite-(Ce), perbøeite-(Ce), törnebohmite-(Ce) and törnebohmite-(La). The new minerals form isolated anhedral grains up to 0.3 mm [ferriperbøeite-(La)] and 0.5 mm [perbøeite-(La)] across and granular aggregates up to 1.5 mm × 0.5 mm [ferriperbøeite-(La)] and 3 mm × 1 mm [perbøeite-(La)]. Both minerals are brownish-black with vitreous lustre. Dcalc = 4.510 [ferriperbøeite-(La)] and 4.483 [perbøeite-(La)] g cm–3. They are optically biaxial (+); ferriperbøeite-(La): α = 1.788(5), β = 1.790(5), γ = 1.810(5) and 2Vmeas = 40(10)°; perbøeite-(La): α = 1.778(8), β = 1.783(8), γ = 1.805(8) and 2Vmeas = 40(10)°. Chemical data [wt.%, electron-microprobe; Fe3+:Fe2+ ratio from charge-balance requirements, H2O by stoichiometry; ferriperbøeite-(La)/perbøeite-(La)] are: CaO 4.91/4.81, ThO2 0.00/0.32, La2O3 23.75/22.16, Ce2O3 19.69/20.05, Pr2O3 0.85/1.09, Nd2O3 1.48/2.18, MgO 1.47/1.38, Al2O3 10.68/11.25, MnO 1.07/0.92, FeO 3.04/3.35, Fe2O3 5.31/3.78, TiO2 0.19/0.19, SiO2 27.47/27.35, F 0.11/0.23, H2O 1.61/1.54, –O = F –0.05/–0.10, total 101.58/100.50. The empirical formulae based on O20(OH,F)2 are for ferriperbøeite-(La): (Ca0.95La1.58Ce1.30Nd0.10Pr0.06)Σ3.99(Al2.27Fe3+0.72Fe2+0.46Mg0.40Mn0.16Ti0.03)Σ4.04Si4.96O20[(OH)1.94F0.06]; and for perbøeite-(La): (Ca0.94Th0.01La1.49Ce1.34Nd0.14Pr0.07)Σ3.99(Al2.42Fe3+0.52Fe2+0.51Mg0.38Mn0.14 Ti0.03)Σ4.00Si4.99O20[(OH)1.87F0.13]. Both minerals are monoclinic, P21/m; the unit-cell parameters [ferriperbøeite-(La)/perbøeite-(La)] are: a = 8.9458(2)/8.9652(4), b = 5.72971(13)/5.7306(2), c = 17.6192(3)/17.6770(9) Å, β = 115.9497(19)/116.053(6)°, V = 812.06(3)/815.88(6) Å3 and Z = 2/2. The crystal structures are solved on a single crystal and converged to R = 0.0355 [ferriperbøeite-(La)] and 0.0750 [perbøeite-(La)]. Ferriperbøeite-(La) and perbøeite-(La) are named as the La-analogues of ferriperbøeite-(Ce) and perbøeite-(Ce), respectively. [ABSTRACT FROM AUTHOR]

Oxybismutomicrolite, ideally [(Bi3+,#)2]Σ4+Ta2O6O, where # = subordinate substituents, such as Na+, Ca2+ and vacancy (□), is a microlite-group, pyrochlore-supergroup mineral discovered at the Solnechnaya ('Sunny') pegmatite vein, Malkhan pegmatite field, Zabaykalskiy Kray, Central Transbaikalia, Russia. It forms rough octahedral crystals up to 1 mm across and equant grains up to 2 mm across embedded in an albite–lepidolite–elbaite complex. Other associated minerals are Bi-rich fluornatromicrolite, bismutotantalite and stibiotantalite. The new mineral is black, with resinous lustre; the streak is greyish white. It is non-fluorescent under ultraviolet light. Oxybismutomicrolite is brittle, with Mohs' hardness of ~5. Cleavage is not observed, fracture is uneven. Dmeas. = 6.98(2) g/cm3 and Dcalc. = 7.056 g/cm3. The mineral is optically isotropic. The mean refractive index calculated from the Gladstone–Dale equation is 2.184. The infrared spectrum shows the absence of H2O molecules and OH groups. The chemical composition is (electron microprobe, wt.%): Na2O 3.45, CaO 2.88, MnO 0.31, PbO 0.76, Bi2O3 29.81, ThO2 0.18, TiO2 3.89, SnO2 1.77, Nb2O5 4.50, Ta2O5 51.08, F 1.17, O = F –0.49, total 99.31. The empirical formula, on the basis of 2 cations at the B site, is (Bi0.79Na0.68Ca0.32Mn0.03Pb0.02□0.16)Σ2.00(Ta1.42Ti0.30Nb0.21Sn0.07)Σ2.00O6.00(O0.52F0.38□0.10)Σ1.00. The crystal structure refinement (R = 0.019) gave the following data: cubic, Fd–3m, a = 10.4746(11) Å, V = 1149.2(4) Å3 and Z = 8. The eight strongest lines of the powder X-ray diffraction pattern [d, Å(I, %)(hkl)] are: 6.051(12)(111), 3.160(10)(311), 3.026(100)(222), 2.621(32)(400), 1.854(33)(440), 1.581(27)(622), 1.514(7)(444) and 1.203(7)(662). Type material is deposited in the collections of the Fersman Mineralogical Museum of the Russian Academy of Sciences, Moscow, Russia, registration number 5409/1. [ABSTRACT FROM AUTHOR]

The Mössbauer, infrared and Raman spectra of iron-rich oxyphlogopite from a new locality, the Bartoy occurrence, Transbaikalia, Russia were obtained and its crystal structure was solved. The mineral is characterized by the absence of OH groups and ordered distribution of Fe2+ and Fe3+ between sites having octahedral coordination. Unlike oxyphlogopite holotype sample which is monoclinic (1M polytype), iron-rich oxyphlogopite belongs to the 3T polytype (space group P3112) with the unit-cell parameters a = 5.3248(2) Å, c = 29.788(3) Å, V = 731.44(8) Å3. Its refined crystal-chemical formula is (Z = 3): A(K0.9Na0.1) [M1(Fe2+0.6Mg0.4) M2(Fe3+0.4Ti0.4Mg0.2) M3(Mg0.4Fe3+0.3Ti0.2Al0.1)] [T1,2(Si0.7Al0.3)2O5]2X(O0.9F0.1)2. [ABSTRACT FROM AUTHOR]

Gladkovskyite (IMA2018-098), MnTlAs3S6, is a new sulfosalt from the Vorontsovskoe gold deposit, Sverdlovsk Oblast', Northern Urals, Russia. The new mineral occurs in limestone breccias cemented by abundant realgar, orpiment, baryte and pyrite, as well as minor clinochlore, fluorapatite, quartz and talc. Gladkovskyite forms long-prismatic crystals and grains up to 0.2 mm; it has dark cherry-red color and red streak. It is transparent with adamantine luster. The Vickers microhardness is 94 kg/mm2. The new mineral is brittle, with uneven fracture; neither cleavage nor parting was observed. The density calculated based on the empirical formula is 4.356 g/cm3. In reflected light, gladkovskyite is grayish-white, strongly anisotropic with rotation tints varying from light-grey to brown. Its pleochroism is moderate, from orange-red to dark-red, and bireflectance is very weak, ΔR = 0.58% (589 nm). The empirical formula of gladkovskyite is Mn1.01Tl0.99Pb0.01 As2.86Sb0.13S6.00 (based on 11 atoms pfu). Prominent features in the Raman spectrum include bands of Mn-S and As-S stretching vibrations as well as numerous low-frequency bands related to phonons. Gladkovskyite is trigonal, R31c, a = 9.6392(2), c = 6.4560(15) Å, V = 519.49(12) Å3 and Z = 2. The seven strongest powder X-ray diffraction lines are [dobs, Å (I, %) (hkl) ]: 5.11 (80) (101), 4.83 (70) (110), 3.49 (50) (201), 3.23 (30) (002), 2.86 (100) (-2-11, 211), 2.68 (30) (112), 2.55 (60) (301, 202). The crystal structure of gladkovskyite was refined from the single-crystal X-ray diffraction data to R = 0.0178 for 679 observed reflections with Iobs > 3s(I). It contains infinite chains of face-sharing MnS6 octahedra, TlS9 polyhedra and pyramidal AsS3 groups; the structure belongs to the group of seldom occurring cyclic sulfosalts. The new mineral honors Russian geologist Boris Aleksandrovich Gladkovsky who discovered the Vorontsovskoe gold deposit. [ABSTRACT FROM AUTHOR]

Solid solutions involving natural Mn3+O(OH) polymorphs, groutite, manganite, and feitknechtite are characterized and discussed based on original and literature data on the chemical composition, powder and single-crystal X-ray diffraction, and middle-range IR absorption spectra of these minerals. It is shown that manganite forms two kinds of solid-solution series, in which intermediate members have the general formulae (i) (Mn4+, Mn3+)O(OH,O), with pyrolusite as the Mn4+O2 end-member, and (ii) (Mn3+, M2+)O(OH, H2O), where M = Mn or Zn. In Zn-substituted manganite from Kapova Cave, South Urals, Russia, the Zn2+:Mn3+ ratio reaches 1:1 (the substitution of Mn3+ with Zn2+ is accompanied by the coupled substitution of OH− with H2O). Groutite forms solid-solution series with ramsdellite Mn4+O2. In addition, the incorporation of OH− anions in the 1 × 2 tunnels of ramsdellite is possible. Feitknechtite is considered to be isostructural with (or structurally related to) the compounds (M2+, Mn3+)(OH, O)2 (M = Mn, Zn) with a pyrochroite-related layered structure. [ABSTRACT FROM AUTHOR]

This paper describes native gold in ore-bearing breccias with realgar-orpiment cement from the Vorontsovskoe gold deposit (Northern Urals, Russia). Particular attention is paid to the morphological features of native gold and its relation to other minerals. The latter include both common (orpiment, barite, pyrite, prehnite, realgar) and rare species (Tl and Hg sulfosalts, such as boscardinite, dalnegroite, écrinsite, gillulyite, parapierrotite, routhierite, sicherite, vrbaite, etc.). The general geological and geochemical patterns of the Turyinsk-Auerbakh metallogenic province, including the presence of small non-economic copper porphyry deposits and general trend in change of the composition of native gold (an increase in the fineness of gold from high-temperature skarns to low-temperature realgar-orpiment breccias) confirm that the Vorontsovskoe deposit is an integral part of a large ore-magmatic system genetically associated with the formation of the Auerbakh intrusion. [ABSTRACT FROM AUTHOR]

The new mineral patynite was discovered at the massif of Patyn Mt. (Patynskiy massif), Tashtagolskiy District, Kemerovo (Kemerovskaya) Oblast', Southern Siberia, Russia. Patynite forms lamellae up to 1 × 0.5 cm and is closely intergrown with charoite, tokkoite, diopside, and graphite. Other associated minerals include monticellite, wollastonite, pectolite, calcite, and orthoclase. Patynite is colorless in individual lamellae to white and white-brownish in aggregates. It has vitreous to silky luster, white streaks, brittle tenacity, and stepped fractures. Its density measured by flotation in Clerici solution is 2.70(2) g/cm3; density calculated from the empirical formula is 2.793 g/cm3. The Mohs' hardness is 6. Optically, patynite is biaxial (−) with α = 1.568(2), β = 1.580(2), and γ = 1.582(2) (589 nm). The 2V (measured) = 40(10)° and 2V (calculated) = 44.1°. The Raman and IR spectra shows the absence in the mineral of H2O, OH−, and CO32− groups and B–O bonds. The chemical composition is (electron microprobe, wt.%): Na2O 3.68, K2O 5.62, CaO 26.82, SiO2 64.27, total 100.39. The empirical formula based on 23 O apfu is Na1.00K1.00Ca4.02Si8.99O23. Patynite is triclinic, space group P 1. The unit-cell parameters are: a = 7.27430(10), b = 10.5516(2), c = 13.9851(3) Å, α = 104.203(2)°, β = 104.302(2)°, γ = 92.0280(10)°, V = 1003.07(3) Å3, Z = 2. The crystal structure was solved by direct methods and refined to R1 = 0.032. Patynite is an inosilicate with a new type of sextuple branched tubular chain [(Si9O23)10−]∞ with an internal channel and [(Si18O46)20−] as the repeat unit. The strongest lines of the powder X-ray diffraction pattern [dobs, Å (I, %) (hkl)] are: 3.454 (100) (2-1-1), 3.262 (66) (2-1-2), 3.103 (64) (02-4), 2.801 (21), 1.820 (28) (40-2). Type material is deposited in the collections of the Fersman Mineralogical Museum of the Russian Academy of Sciences, Moscow, Russia with the registration number 5369/1. [ABSTRACT FROM AUTHOR]

Tsygankoite, ideally Mn8Tl8Hg2(Sb21Pb2Tl)Σ24S48, is a new sulfosalt discovered at the Vorontsovskoe gold deposit, Northern Urals, Russia. It occurs as lath-like elongated crystals up to 0.2 mm embedded in calcite–dolomite–clinochlore matrix. The associated minerals also include aktashite, alabandite, arsenopyrite, barite, cinnabar, fluorapatite, orpiment, pyrite, realgar, routhierite, sphalerite, tilasite, and titanite. The new mineral is non-fluorescent, black, and opaque with a metallic lustre and black streak. It is brittle with an uneven fracture and no obvious parting and cleavage. Its Vickers hardness (VHN10) is 144 kg/mm2 (range 131–167 kg/mm2) and its calculated density is 5.450 g·cm−3. In reflected light, tsygankoite is white; between crossed polars it is dark grey to black. It is strongly anisotropic: rotation tints vary from light grey to dark grey to black. Pleochroism and internal reflections are not observed. The chemical composition of tsygankoite (wt %, electron-microprobe data) is: Mn 6.29, Hg 5.42, Tl 26.05, Pb 5.84, As 3.39, Sb 30.89, S 21.87, total 99.75. The empirical formula, calculated on the basis of 90 atoms pfu, is: Mn8.06Tl8.00Hg1.90(Sb17.87As3.19Pb1.99Tl0.97)Σ24.02S48.03. Tsygankoite is monoclinic, space group C2/m, a = 21.362(4) Å, b = 3.8579(10) Å, c = 27.135(4) Å, β = 106.944(14)°, V = 2139.19(17) Å3 and Z = 1. The five strongest diffraction peaks from X-ray powder pattern (listed as (d,Å(I)(hkl)) are: 3.587(100)(112), 3.353(70)(−114), 3.204(88)(405), 2.841(72)(−513), and 2.786(99)(−514). The crystal structure of tsygankoite was refined from single-crystal X-ray diffraction data to R = 0.0607 and consists of an alternation of two thick layer-like arrays, one based on PbS-archetype and the second on SnS-archetype. Tsygankoite has been approved by the IMA-CNMNC under the number 2017-088. It is named for Mikhail V. Tsyganko, a mineral collector from Severouralsk, Northern Urals, Russia, who collected the samples where the new mineral was discovered. [ABSTRACT FROM AUTHOR]

Maletoyvayamite, Au3Se4Te6, is a new mineral discovered in a heavy-mineral concentrate from the Gaching occurrence of the Maletoyvayam deposit, Kamchatka, Russia (60°19′51.87″N, 164°46′25.65″E). It forms anhedral grains (10 to 50 μm in size) and is found in intergrowths with native gold (Au–Ag), Au tellurides (calaverite), unnamed phases (AuSe, Au2TeSe and Au oxide), native tellurium, sulfosalts (tennantite, tetrahedrite, goldfieldite and watanabeite) and supergene tripuhyite. Maletoyvayamite has a good cleavage on {010} and {001}. In plane-polarised light, maletoyvayamite is grey, has strong bireflectance (grey to bluish grey), and strong anisotropy; it exhibits no internal reflections. Reflectance values for maletoyvayamite in air (R min, R max in %) are: 38.9, 39.1 at 470 nm; 39.3, 39.5 at 546 nm; 39.3, 39.6 at 589 nm; and 39.4, 39.7 at 650 nm. Sixteen electron-microprobe analyses of maletoyvayamite gave an average composition: Au 34.46, Se 16.76, Te 47.23 and S 0.84, total 99.29 wt.%, corresponding to the formula Au2.90(Se3.52S0.44)Σ3.96Te6.14 based on 13 atoms; the average of eleven analyses on synthetic analogue is: Au 34.20, Se 19.68 and Te 45.42, total 99.30 wt.%, corresponding to Au2.90Se4.16Te5.94. The calculated density is 7.98 g/cm3. The mineral is triclinic, space group P 1 , with a = 8.901(2), b = 9.0451(14), c = 9.265(4) Å, α = 97.66(3), β = 106.70(2), γ = 101.399(14)°, V = 685.9(4) Å3 and Z = 2. The crystal structure of maletoyvayamite represents a unique structure type resembling a molecular structure. There are cube-like [Au6Se8Te12] clusters linked via van der Waals interactions. The structural identity of maletoyvayamite with the synthetic Au3Se4Te6 was confirmed by powder X-ray diffraction and Raman spectroscopy. [ABSTRACT FROM AUTHOR]