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The new mineral zilbermintsite-(La), ideally (CaLa5)(Fe3+Al3Fe2+)[Si2O7][SiO4]5O(OH)3, was found in a single polymineralic nodule from the Mochalin Log REE deposit, Chelyabinsk Oblast, South Urals, Russia. Zilbermintsite-(La) forms anhedral grains up to 0.65 × 0.20 mm at the contact of ferriperbøeite-(La), törnebohmite-(La) and ferriallanite-(Ce). Other associated minerals include bastnäsite-(La), biraite-(La), ferriallanite-(La), ferriperbøeite-(Ce), fluorbritholite-(Ce), monazite-(La), perbøeite-(La), percleveite-(Ce), percleveite-(La), perrierite-(Ce), perrierite-(La), thorianite, thorite and quartz. The new mineral is light brown, translucent in thin fragments with a vitreous lustre. It is brittle, with good {100} cleavage. Mohs hardness is ca. 6. D calc = 4.684 g cm–3. Optically, zilbermintsite-(La) is biaxial (+), α = 1.805(7), β = 1.812(7) and γ = 1.867(8) (589 nm); 2Vmeas = 40(15)° and 2Vcalc = 40°. The empirical formula based on O28(OH,F)3 apfu is (Ca0.94La2.56Ce2.18Nd0.20Pr0.10Th0.02)Σ6.00(Al2.96Fe3+0.90Fe2+0.64Mg0.34Mn0.13Ti0.03)Σ5.00Si7.00O28[(OH)2.42F0.58]. Zilbermintsite-(La) is monoclinic, P 21/ m ; the unit-cell parameters are: a = 8.9605(5), b = 5.7295(2), c = 25.1033(13) Å, β = 116.616(7), V = 1152.21(12) Å3 and Z = 2. The crystal structure of zilbermintsite-(La) is solved from the single-crystal X-ray diffraction data [ R = 0.0757 for 2857 unique reflections with I > 2σ(I)]. The new mineral is isotypic to radekškodaite-(La) and radekškodaite-(Ce) and together with them forms the newly defined radekškodaite group. All members of this group possess the ET2 type structure where one epidote-type module (E) regularly alternates with two törnebohmite-type modules (T). The new mineral honours Professor Veniamin A. Zilbermints (1887–1939) who was a pioneer of the study of the Mochalin Log deposit. The Levinson suffix-modifier -(La) indicates the predominance of La among rare-earth elements in the mineral. [ABSTRACT FROM AUTHOR]

Mangani-eckermannite, ideally NaNa2(Mg4Mn3+)Si8O22(OH)2, is a new member of the amphibole supergroup found at Tanohata Mine, Shimohei District, Iwate Prefecture, Japan. It occurs as prismatic crystals up to 0.3 × 0.2 mm and their aggregates up to 1 mm intergrown with braunite, vittinkiite and quartz. Mangani-eckermannite is cherry-red to very dark red and reddish-brown in thicker grains. It is translucent with a pinkish white streak and vitreous lustre. It is brittle, fracture is stepped along crystal elongation and uneven across a crystal. Cleavage is perfect on {110}. Mohs hardness is 6. D meas = 3.16(2) and D calc = 3.186 g/cm3. The mineral is optically biaxial (–), with α = 1.645(3), β = 1.668(2), γ = 1.675(3) (589 nm); 2Vmeas = 60(10)°, 2Vcalc = 57°. The empirical formula derived from electron microprobe analysis, secondary-ion mass spectrometry and single-crystal structure refinement and calculated on the basis of 24 (O+OH) atoms per formula unit (apfu) is A(Na0.74K0.24□0.02)Σ1.00B(Na1.52Ca0.24Mn2+0.24)Σ2.00C(Mg2.54Mn2+1.45Mn3+0.71Fe3+0.26Ti0.04)Σ5.00T(Si7.97Al0.03)Σ8.00O22W[(OH)1.52O0.48]Σ2.00. Mangani-eckermannite is monoclinic, space group C 2/ m , a = 9.9533(4), b = 18.1440(7), c = 5.2970(2) Å, β = 103.948(4)°, V = 928.39(6) Å3 and Z = 2. The strongest lines of the powder X-ray diffraction pattern [ d , Å (I , %)(hkl)] are: 8.52(100)(110); 4.54(25)(040); 3.41(29)(131); 3.16(23)(310,201); 2.721(37)(151); 2.533(26)($\bar{2}$ 02). The crystal structure was refined to R 1 = 0.0264 for 1001 independent reflections with I > 2σ(I). The place of mangani-eckermannite in the nomenclature of the amphibole supergroup is discussed and the status of mangano-ferri-eckermannite as a valid mineral species and successor of 'kôzulite' is questioned. [ABSTRACT FROM AUTHOR]

Thermal expansion of metatorbernite, Cu(UO2)2(PO4)2(H2O)8 (1), and metazeunerite, Cu(UO2)2(AsO4)2(H2O)8 (2), has been investigated using single-crystal and powder X-ray diffraction. Both minerals are prone to dehydration, which proceeds already at ambient conditions. According to the single-crystal XRD data, 1 is stable up to 300(50) K, while 2 is stable up to 250(50) K. Powder XRD studies at various temperatures suggest that 1 dehydrates in three stages at ca. 353, 373, and 483 K, while 2 in two stages at ca. 283 and 543 K. Calculation of the main coefficients of thermal expansion reveals strong anisotropy. The expansion is maximal in the direction normal to the autunite-type layers. This correlates with the anisotropy in thermal evolution of Cu–O bond lengths and differences in the thermal behavior of PO4 and AsO4 tetrahedra. [ABSTRACT FROM AUTHOR]

Napoliite, ideally Pb2OFCl, is a new fluoroxychloride mineral found in a specimen from a fumarole formed subsequent to the 1944 eruption of Vesuvius volcano, Naples Province, Italy. It occurs as well-shaped lamellar crystals up to 0.25 × 0.25 × 0.01 mm typically forming clusters up to 0.4 × 0.4 mm on the surface of volcanic scoria in association with anglesite, artroeite, atacamite, calcioaravaipaite, cerussite, challacolloite, cotunnite, hephaistosite, manuelarossiite, matlockite and susannite. Napoliite is colourless with white streak and adamantine lustre. It is brittle and has a laminated fracture. Cleavage is perfect on {001}. D calc = 7.797 g cm–3. The calculated mean refractive index is 2.10. Chemical composition (wt.%, electron microprobe) is: PbO 91.71, F 3.89, Cl 7.34, –O=(F+Cl) –3.30, total 99.64. The empirical formula calculated on the basis of 3 anions is Pb1.999O0.997F0.996Cl1.007. Raman spectroscopy confirms the absence of OH– groups and H2O molecules in the mineral. Napoliite is tetragonal, space group P 42/ mcm , a = 5.7418(11), c = 12.524(4) Å, V = 412.9(2) Å3 and Z = 4. The strongest lines of the powder X-ray diffraction pattern [ d , Å (I , %) (hkl)] are: 3.860 (85) (111); 3.139 (20) (004); 2.914 (100) (113); 2.866 (63) (200); 2.118 (19) (204); 2.027 (19) (220); 1.665 (20) (313); and 1.642 (23) (117). The crystal structure was refined to R 1 = 0.024 for 222 reflections with F > 4σ(F). It is based on lead oxide blocks derived from that of litharge PbO, which alternate with layers of chloride ions. Napoliite represents a new structure type with a unique order/disorder pattern of fluorine and oxygen atoms. The new mineral is dimorphous with rumseyite. It is named after the city of Naples (Napoli in Italian). [ABSTRACT FROM AUTHOR]

In this study, galeite, Na15(SO4)5ClF4 and schairerite, Na21(SO4)7ClF6 were investigated via in situ single-crystal X-ray diffraction in the temperature range of 300–750 K. Galeite and schairerite are trigonal, P31m, a = 12.1903(2), c = 13.9454(2) Å, V = 1794.69(6) Å3, and Z = 3 (R1 = 0.0273, 300 K) for galeite and a = 12.1859(3), c = 19.3080(6) Å, V = 2483.04(14) Å3, and Z = 3 (R1 = 0.0334, 300 K) for schairerite. The crystal structures of galeite and schairerite are based upon frameworks consisting of alternating face- and corner-sharing fluorine- and chlorine-centered octahedra. Galeite and schairerite can be attributed to 5H (galeite) and 7H (schairerite) antiperovskite polytypes, respectively. It was observed that schairerite undergoes at least one reversible phase transition before it starts to lose its crystallinity at 750 K. This phase transition occurs in the temperature range of 550–600 K. The high-temperature modification of schairerite is trigonal, with the centrosymmetric space group P-3m1 and the unit-cell parameters a = 7.0714(2), c = 19.5972(7) Å, V = 848.66(6) Å3, and Z = 1. Galeite is stable up to 600 K. The crystal structures of minerals expand anisotropically, and, in both cases, the strongest thermal expansion was parallel to the modules of face-sharing anion-centered octahedra. The structural complexity analysis showed that galeite is complex (695.175 bits/cell) and that the LT-modification of schairerite is very complex (1064.990 bits/cell), whereas its HT-modification is intermediate in complexity (256.755 bits/cell). The complexities of LT- and HT-polymorphs of schairerite are consistent with the general observations regarding structures with positional disorder: complexity decreases with increasing temperature, and simpler polymorphs have lower physical density. [ABSTRACT FROM AUTHOR]

The crystal structure of a naturally occurring layered double hydroxide mineral—desautelsite from San Benito County, California, USA—was refined using single-crystal X-ray diffraction data in the space group R-3m, a = 3.1238(2) Å, c = 23.528(3) Å, V = 198.83(4) Å3, and Z = 3/8. The Mg and Mn cations are disordered occurring in one M site with occupancy Mg0.77Mn0.23. According to the electron microprobe analysis supported by Raman spectroscopy, the empirical formula is Mg6.20(MnIII1.78Al0.01FeIII0.01)Σ1.80(OH)16(CO3)0.90·5.35H2O that shows higher content of interlayer (H2O) molecules in comparison to the ideal formula that also agrees with the structure refinement. The Raman spectroscopy of two samples indicated O–H vibrations (3650/3640 cm−1, ~3500 sh cm−1), symmetric C–O (1055/1057 cm−1), Mg–O–Mg (533/533 cm−1) and Mn–O–Mn (439/438 cm−1) stretching vibrations and lattice vibrations (284/287 cm−1). Summing up our data and that of the current literature, we show a correlation (R2 = 0.91) between the averaged effective ionic radius (x) and a unit cell parameter (y) of hydrotalcite group minerals, y = 1.9871 x + 1.4455 . Desautelsite follows this correlation, being the species with one of the largest a unit cell parameters among the group. The correlation can be applied for control of cation intercalation during synthesis. [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]

The new mineral amgaite was discovered at the Khokhoyskoe gold deposit, 120 km W of Aldan town, Aldanskiy District, Sakha Republic (Yakutia), Eastern Siberia, Russia. Amgaite forms fine-grained colloform aggregates up to 0.05 mm across, and is often intimately intergrown with avicennite, unidentified carbonates and antimonates of Tl. Other associated minerals include gold, silver, acanthite, arsenopyrite, pyrite, berthierite, chalcocite, weissbergite, chlorargyrite, calcite, quartz, goethite etc. Amgaite is dark reddish brown to black. It has submetallic luster, black streak, brittle tenacity and conchoidal fracture. Its density calculated from the empirical formula and powder XRD data is 8.358 g/cm3. Its Mohs' hardness is ca. 1.5–2. Optically, amgaite is uniaxial. In reflected light, it is gray with a bluish shade, very weakly anisotropic with rare brownish red internal reflections. Reflectance values for the four COM wavelengths [Rmin, Rmax (%)(λ in nm)] are: 13.5, 14.2 (470); 12.7, 13.2 (546); 12.3, 12.7 (589); and 11.7, 12.3 (650). The Raman spectrum shows bands of Te–O and Tl–O bonds and confirms the absence in amgaite of H2O, OH–, CO32– groups and B–O bonds. The chemical composition is (electron microprobe, wt.%): MgO 0.43, CaO 1.62, Fe2O3 0.36, Tl2O3 66.27, Sb2O5 3.48, TeO3 27.31, total 99.47. The empirical formula based on 6 O apfu is Tl3+1.74Ca0.17Mg0.06Fe3+0.03Te6+0.93Sb5+0.13O6. Amgaite is trigonal, space group P321; unit-cell parameters are as follows: a = 9.0600(9), c = 4.9913(11) Å, V = 354.82(8) Å3, Z = 3. The strongest lines of the powder X-ray diffraction pattern [dobs, Å (I, %) (hkl)] are as follows: 3.352 (100) (111), 3.063 (15) (201), 2.619 (49) (300), 2.065 (18) (221), 1.804 (28) (302), 1.697 (8) (321), 1.625 (9) (411). The crystal structure of amgaite is the same as of synthetic Tl3+2Te6+O6. The new mineral is named after the Amga River, the basin of which hosts the type locality, Khokhoyskoe occurrence. The type material is deposited in the collections of the Fersman Mineralogical Museum of the Russian Academy of Sciences, Moscow, Russia, with the registration number 5773/1. [ABSTRACT FROM AUTHOR]