A new mineral iskandarovite, Sb 6 O 7 (SO 4 ) 2 was discovered at the tract of Kukhi-Malik, Fan-Yagnob coal deposit, ca.75 km N of Dushanbe, Tajikistan.Iskandarovite is an exhalative mineral formed directly from a gas of the natural underground coal fire.The mineral forms colorless prismatic crystals (50-120 m).Mohs hardness is ~ 2.0.Refractive indices: = 1.985(3), = 2.052(5), (calc.)= 2.069(9) (590 nm).The mineral is non-soluble in H 2 O and ethanol at room temperature.Raman spectra show the absence of water, hydroxyl, carbonate, or other anions.The chemical composition determined by electron-microprobe analysis is (wt.%):Sb 2 O 3 -82.57;Bi 2 O 3 -1.28;As 2 O 3 -0.05;SO 3 -15.17;total -99.07.The empirical formula (based on 15 O apfu) is: Sb 5.95 Bi 0.06 As 0.01 S 1.99 O 15 .The strongest lines of the X-ray powder diffraction pattern are (d-I-hkl): 10. 1-40-110; 5.08-50-220; 3.26-25-311; 3.146-100-241; 2.933-73-331.Iskandarovite is orthorhombic, Ccc2, unit-cell parameters a = 12.0402(3), b = 18.9599(5), c = 5.8638(2) , V = 1338.59(7) 3 , Z = 4, and the crystal structure was refined to R 1 = 0.0236 on the basis of 2053 unique reflections with F o > 4F o .The crystal strucure of iskandarovite is based on sulfate tetrahedra and [O 7 Sb 6 ] 4+ rod-like chains that are elongated along the c axis.Synthetic Sb 6 O 7 (SO 4 ) 2 analogue is known.The crystal chemistry of 13 known Sb(III) sulfates and oxysulfates is reviewed.

Twenty extra-framework S-and C-bearing species including anions (SO 4 2-, SO 3 2-, S 2- , S 5 2-, HS -, CO 3 2-, C 2 O 4 2-, HCO 4 -), radical anions (S 2 -, S 3 -, cis-and trans-S 4 -, SO 4 -) and neutral molecules (CO 2 , COS, H 2 S, cis-and trans-S 4 , S 6 ) have been identified in natural tectosilicates (members of the sodalite, cancrinite and scapolite groups) using a novel multimethodic approach based on several spectroscopic methods as well as single-crystal and powder X-ray diffraction as well as electron microprobe and wet chemical analyses.Various polysulfide groups were detected in lazurite, hayne, vladimirivanovite, sapozhnikovite, slyudyankaite, kyanoxalite, balliranoite, marinellite, tounkite, bystrite, sulfhydrylbystrite, and meionite.Experimental data on mutual conversions of S-bearing species and structure modulations of these minerals under different temperatures, reducing and oxidizing environment as well as radiation-induced conversions provide a key for their use as markers of the crystallization or transformation conditions in nature and during synthesis and modifying.

Hydrated sodium and magnesium sulfates are fairly common minerals.This study is focused on lweite from the fumaroles of the Tolbachik volcano in Kamchatka.The crystal structure of lweite was refined using single-crystal X-ray diffraction, and the hydrogen atoms were localized for the first time.In situ single-crystal (temperature range -173 to 227 C) and powder (temperature range -173 to 900 C) X-ray studies were performed.Both techniques show that lweite remains stable up to about 220 C without showing any signs of potential phase transitions.The mineral is also stable under a vacuum of 600 Pa.The following transformation sequence for lweite was observed upon heating: lweite metathnardite + vanthoffite + "x-phase" metathnardite + periclase.The thermal expansion of lweite demonstrates two distinct patterns in two temperature ranges.There is virtually no expansion in the structure until -93 C.Following this, the structure rapidly expands, exhibiting a highly anisotropic behavior.Shear deformations of the

Anomalously high orthopyroxene is an unexpected feature of some depleted peridotite xenoliths from the cratonic lithosphere.This investigation presents new petrographic, geochemical, and thermodynamic modelling data on silica-rich spinel harzburgites and one garnet-spinel harzburgite from the Kaapvaal Craton, South Africa, to constrain the pressuretemperature (P-T) conditions of orthopyroxene formation.At the time of sampling by the host kimberlite, the garnet-spinel harzburgite resided on the geotherm at 25 kbar, 765C, while the compositionally similar garnet-free samples probably equilibrated at broadly comparable P-T conditions.The samples are subdivided into 'bronzite type' peridotites characterised by orthopyroxene with micrometre scale exsolutions of spinel clinopyroxene, and 'normal type' peridotites in which orthopyroxene does not contain visible exsolved phases.The presence of these exsolved phases indicates unmixing from a more Al-Cr-(Ca)-rich precursor orthopyroxene i.e. an original orthopyroxene that precipitated from and was in equilibrium with the Si-enriching agent at high temperature, before cooling and undergoing sub-solidus

Calciopharmacoalumite, ideally Ca 0.5 Al 4 (AsO 4 ) 3 () 4 5H 2 O, was found at the Obdilya gold ore deposit located within the Chauvai ore field (Kyrgyzstan).Calciopharmacoalumite occurs as clusters of light-brown "iron-bearing" cubic crystals and white iron-free polycrystalline masses overgrown with prismatic vladimirite crystals.Calciopharmacoalumite is associated also with mansfieldite, talmessite, tapiaite and various amorphous K-Ca-Fe-Al arsenates.Calciopharmacoalumite is cubic P-43m, a = 7.758(5) , V = 801.9(7) 3 , R 1 = 0.043.The eight strongest lines of the X-ray powder diffraction pattern are [I-d()-hkl]: 100-7.76-100; 60-4.47-111;33-3.880-200;30-3.166-211;51-2.746-220;16-2.457-310;19-2.339-311.The chemical composition determined by electron-microprobe analysis is (wt.%): As 2 O 5 48.05,Al 2 O 3 20.89;Fe 2 O 3 7.42; CaO 5.09; MgO 2.33; SrO 0.33; K 2 O 1.24; H 2 O 17.97, total 103.32.The empirical formula calculated on the basis of As = 3 atoms per formula unit is (Ca 0.65 K 0.19 Sr 0.02 ) 1.53+ 0.86 (Al 2.94 Fe 3+ 0.66 Mg 0.40 ) 11.60+ 4.00 (AsO 4 ) 3 9-((OH) 3.87 O 0.13 ) 4.13- 4.00 5.19(H 2 O).Calciopharmacoalumite is the first Ca-dominant member of the pharmacosiderite supergroup.The origin of the new mineral is assumed to be lowtemperature hydrothermal or hypergenic.

The following study reveals the mineralogy and origin of peculiar silica-carbonate bodies (i.e.listvenite) associated with tectonized serpentinites and Permian-Triassic phyllites from the Tokat region in northern Turkey.The listvenite includes green-coloured opaline silica intersected by saddle dolomite and minor sulphide mineralization (pyrite, cobaltite, and enargite).It also hosts abundant chalcedonic bodies (i.e.vein agate) of bluish to bluish-white colouration.Listvenite-hosted opaline silica has been recognized as lussatite (i.e. a fibrous birefringent opal-CT variety) with a dominantly ,,tridymitic" structure, whilst its green colouration results from discrete, but widely disseminated Cr-bearing smectite-group

Cuprodongchuanite (IMA2021-065), Pb 4 CuZn 2 (PO 4 ) 2 (PO 4 ) 2 (OH) 2 , is a new mineral from Sanguozhuang Village, Yunnan Province, China.It occurs as striking apple green crust-like radial or spherical aggregates of microscopic blade-like crystals on hemimorphite.Cuprodongchuanite is brittle with an irregular fracture, a Mohs hardness of 2-3, and perfect cleavage on {011}.The calculated density is 6.10 g/cm 3 .The empirical chemical formula is (Pb 4.06 Ca 0.02 ) 4.08 (Cu 1.07 Cd 0.01 ) 1.08 Zn 2.03 [(P 0.74 As 0.20 S 0.01 Si 0.01 ) 0.96 O 4 ] 2 (PO 4 ) 2 (OH) 2 based on 18 O atoms per formula unit.Cuprodongchuanite is triclinic, space group P-1(#2), with unit-cell parameters.a = 4.7405(3) , b = 8.5023(5) , c = 10.2897(6), = 97.206(5), = 101.877(5), = 91.786(5), V = 401.95(4) 3 , and Z = 1.Cuprodongchuanite's name combines the prefix "cupro" (for copper) with the root "dongchuanite".As a member of the dongchuanite group, cuprodongchuanite features a dongchuanite-type structure with the general formula A 4 VI B IV B 2 (X1O 4 ) 2 (X2O 4 ) 2 (OH) 2 .In addition to providing a detailed characterisation of cuprodongchuanite, this study delves deeper into exploring the Jahn-Teller effect of Cu 2+ ions at the VI B site, an important factor in the mineral's crystallography.Employing the oct parameter, the study quantitatively links the degree of octahedral distortion to the Cu-Zn ratio.This method provides a refined understanding of the dongchuanite-type structure and offers an example for assessing similar mineral compositions where cations exhibit closely related properties.