Nitscheite, (NH4)2[(UO2)2(SO4)3(H2O)2]·3H2O, a new mineral with an unusual uranyl-sulfate sheet
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Abstract Nitscheite (IMA2020-078), (NH4)2[(UO2)2(SO4)3(H2O)2]·3H2O, is a new mineral species from the Green Lizard mine, Red Canyon, San Juan County, Utah, U.S.A. It is a secondary phase found in association with chinleite-(Y), gypsum, pyrite, and Co-rich rietveldite. Nitscheite occurs in subparallel and divergent intergrowths of yellow prisms, up to about 0.3 mm in length. Crystals are elongated on [101] and exhibit the forms {100}, {010}, {001}, and {111}. The mineral is transparent with vitreous luster and very pale-yellow streak. It exhibits bright green fluorescence under a 405 nm laser. The Mohs hardness is ~2. The mineral has brittle tenacity, curved fracture, and one good cleavage on {010}. The measured density is 3.30(2) g·cm−3. The mineral is easily soluble in H2O at room temperature. The mineral is optically biaxial (–), α = 1.560(2), β = 1.582(2), γ = 1.583(2) (white light); 2Vmeas = 17(1)°; no dispersion; orientation X = b, Z ≈ [101]; pleochroism X colorless, Y and Z yellow; X < Y ≈ Z. Electron microprobe analysis provided the empirical formula (NH4)1.99U2.00S3.00O21H10.01. Nitscheite is monoclinic, P21/n, a = 17.3982(4), b = 12.8552(3), c = 17.4054(12) Å, β = 96.649(7)°, V = 3866.7(3) Å3, and Z = 8. The structure (R1 = 0.0329 for 4547 I > 3σI reflections) contains [(UO2)2(SO4)3(H2O)2]2− uranyl-sulfate sheets, which are unique among minerals, with NH4 and H2O groups between the sheets.Keywords:
Pleochroism
Monoclinic crystal system
The new mineral whelanite, Cu2Ca6[Si6O17(OH)](CO3)(OH)3(H2O)2, was approved by the Commission on New Minerals and Mineral Names (IMA) in 1977, but until now a description has not been published. The mineral is orthorhombic with space group Pn2n and cell parameters a = 5.6551(4), b = 3.683(3), c = 27.1372(7) Å, V = 565.3(5) Å3, and Z = 1. The mineral occurs with thaumasite, stringhamite, and kinoite in a copper-rich, diopside-garnet-magnetite skarn at the Bawana mine, Beaver County, Utah, and has also been confirmed to occur at other localities. At the Bawana mine, it is found as irregular clusters and radial aggregates of platy to lath-like crystals up to 1 mm in length, flattened on {001} and elongated on [100]. The color and streak are pale blue and the luster is vitreous. The laths are flexible, but not elastic. Cleavage is perfect on {001} and good on {010}, producing splintery fracture. The Mohs’ hardness is about 2½. The measured density is 2.74(3) g/cm3 and the calculated density is 2.737 g/cm3 based upon the empirical formula. The mineral is biaxial (-), α = 1.612(2), β = 1.622(calc), and γ = 1.626(2), and 2Vmeas = 64(1)°. The pleochroism is weak: X = Y (pale blue) < Z (light blue). The optical orientation is X = a, Y = c, Z = b. A combination of electron microprobe analyses and thermogravimetric analyses (for CO2 and H2O) yielded: CaO 34.46, CuO 12.09, FeO 1.52, SiO2 37.96, CO2 5.93, H2O 8.86, total 100.82 wt%, providing the empirical formula (based on O = 26):
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Abstract Protocaseyite, [Al4(OH)6(H2O)12][V10O28]·8H2O, is a new mineral (IMA2020-090) occurring in low-temperature, post-mining, secondary mineral assemblages at the Burro mine, Slick Rock district, San Miguel County, Colorado, U.S.A. Crystals of protocaseyite are saffron-yellow, thick blades, with pale orange-yellow streak, vitreous luster, brittle tenacity, curved fracture, two very good cleavages, a Mohs hardness of 2, and a density of 2.45(2) g/cm3. The optical properties of protocaseyite could be only partly determined: biaxial with α = 1.755(5), β < 1.80, γ > 1.80 (white light); pleochroic with X and Y yellow, Z orange (X ≈ Y < Z). Electron-probe microanalysis and crystal-structure solution and refinement provided the empirical formula [(Al3.89Mg0.11Ca0.02)Σ4.02(OH)6(H2O)12][H0.06V10O28]·8H2O. Protocaseyite is triclinic, P1, a = 9.435(2), b = 10.742(3), c = 11.205(3) Å, α = 75.395(7), β = 71.057(10), γ = 81.286(6)°, V = 1036.4(5) Å3, and Z = 1. The crystal structure (R1 = 0.026 for 4032 Io>2 σI reflections) contains both the [V10O28]6− decavanadate polyoxoanion and a novel [Al4(OH)6(H2O)12]6+ polyoxocation.
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Abstract The new mineral canutite (IMA2013-070), NaMn 3 [AsO 4 ][AsO 3 (OH)] 2 , was found at two different locations at the Torrecillas mine, Salar Grande, Iquique Province, Chile, where it occurs as a secondary alteration phase in association with anhydrite, halite, lavendulan, magnesiokoritnigite, pyrite, quartz and scorodite. Canutite is reddish brown in colour. It forms as prisms elongated on [ 20 ] and exhibiting the forms {010}, {100}, {10 }, {201} and {102}, or as tablets flattened on {102} and exhibiting the forms {102} and {110}. Crystals are transparent with a vitreous lustre. The mineral has a pale tan streak, Mohs hardness of 2½, brittle tenacity, splintery fracture and two perfect cleavages, on {010} and {101}. The calculated density is 4.112 g cm −3 . Optically, canutite is biaxial (+) with α = 1.712(3), β = 1.725(3) and γ = 1.756(3) (measured in white light). The measured 2V is 65.6(4)°, the dispersion is r < v (slight), the optical orientation is Z = b ; X ^ a = 18° in obtuse β and pleochroism is imperceptible. The mineral is slowly soluble in cold, dilute HCl. The empirical formula (for tabular crystals from near the mineshaft), determined from electron - microprobe analyses, is (Na 1.05 Mn 2.64 Mg 0.34 Cu 0.14 Co 0.03 ) ∑4.20 As 3 O 12 H 1.62 . Canutite is monoclinic, C 2/ c , a = 12.3282(4), b = 12.6039(5), c = 6.8814(5) Å, β = 113.480(8)°, V = 980.72(10) Å 3 and Z = 4. The eight strongest X-ray powder diffraction lines are [ d obs Å( I )( hkl )]: 6.33(34)(020), 4.12(26)( 21), 3.608(29)(310, 31), 3.296(57)( 12), 3.150(28)(002,131), 2.819(42)(400,041,330), 2.740(100)(240, 02,112) and 1.5364(31)(multiple). The structure, refined to R 1 = 2.33% for 1089 F o > 4σ F reflections, shows canutite to be isostructural with protonated members of the alluaudite group.
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Summary Specimens of layered baryte containing a range of pyrite forms, including framboids, framboidal aggregates, spherulites, polyhedra, and zoned euhedral crystals from Kempfield, New South Wales, Australia, have been examined by mineragraphy, X-ray diffraction (XRD), X-ray fluorescence (XRF), and electron-probe microanalysis (EPMA). These investigations showed that the pyrite occurred in two forms—an arsenical variety containing approximately 5% arsenic in solid solution within the pyrite and a non-arsenical variety. EPMA studies indicate that the framboids and the cores of the zoned euhedral crystals have similar levels of arsenic and a genetic relationship is deduced to exist between these forms.
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Argandite, Mn7(VO4)2(OH)8, is a new mineral from the metamorphosed synsedimentary exhalative Mn deposit located underneath the Pipji glacier (Pipjigletscher) in the Turtmann valley, Central Alps, Switzerland. The mineral is dedicated to the Swiss geologist Émile Argand (1879-1940). Argandite occurs in manganosite-rich ores in association with the V-minerals pyrobelonite, reppiaite, and an unknown silico-vanadate with chemical formula (Mn,Mg)24(V,As,Si)4Si2O27H38; these minerals result from the remobilization of ore components during the Tertiary Alpine metamorphism under upper greenschist facies conditions (-450 °C, 4-6 kbar). Argandite forms isolated anhedral grains up to 60 μm in diameter. The mineral is transparent, orange in color with a pale orange streak and vitreous luster, Mohs hardness -3.5-4, Dcalc 3.67(1), and Dmeas 3.71(5) g/cm3. It is brittle with one distinct cleavage, probably parallel to {001}. Argandite is biaxial negative, with α -1.74, β = 1.762(4), γ -1.77 (white light), 2V (calc) = -62°. It shows a distinct pleochroism under polarized light, orange-yellow to orange. The empirical chemical formula is (Mn6.54Mg0.38Ni0.04Ca0.02Zn0.01Sr0.01)Σ=7.00(V1.46,As0.54)Σ=2.00O8(OH)8.00. Argandite is monoclinic, space group P21/n, a = 5.5038(2), b = 12.2665(5), c = 10.1055(5) Å, β = 95.559(4)°; V = 679.04(5) Å3; Z = 2. The six strongest lines measured in the X‑ray powder diffraction pattern are [d in Å (I)(hkl)]: 3.074 (100)(131), 2.687 (70)(140;113), 3.395 (60)(112), 3.708 (50) (112;121), 2.945 (50)(041;113), and 2.522 (50)(004;202). The crystal structure was solved with direct methods on the basis of 1661 unique reflections with I > 4σF and refined to R1 = 3.40%. Argandite is isostructural with allactite, Mn7(AsO4)2(OH)8, and raadeite, Mn7(PO4)2(OH)8.
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Abstract Seaborgite (IMA2019-087), LiNa6K2(UO2)(SO4)5(SO3OH)(H2O), is a new mineral species from the Blue Lizard mine, Red Canyon, San Juan County, Utah, U.S.A. It is a secondary phase found on gypsum in association with copiapite, ferrinatrite, ivsite, metavoltine, and römerite. Seaborgite occurs in sprays of light-yellow, long flattened prisms or blades, up to about 0.2 mm in length. Crystals are elongated on [100], flattened on {010}, and exhibit the forms {100}, {010}, {001}, and {101}. The mineral is transparent with vitreous luster and very pale-yellow streak. It exhibits bright lime-green fluorescence under a 405 nm laser. The Mohs hardness is ~2½. The mineral has brittle tenacity, curved or conchoidal fracture, and one good cleavage on {100}. The measured density is 2.97(2) g/cm3. The mineral is immediately soluble in H2O at room temperature. The mineral is optically biaxial (–), α = 1.505(2), β = 1.522(2), γ = 1.536(2) (white light); 2Vmeas = 85(1)°; moderate r < ν dispersion; orientation X ^ a ≈ 10°; pleochroic X colorless, Y and Z light green-yellow; X < Y ≈ Z. EPMA and LA-ICP-MS analyses of seaborgite undermeasured its Li, K, and Na. The empirical formula using Li, Na, and K based on the structure refinement is Li1.00Na5.81K2.19(UO2)(SO4)5(SO3OH)(H2O). Seaborgite is triclinic, P1, a = 5.4511(4), b = 14.4870(12), c = 15.8735(15) Å, α = 76.295(5), β = 81.439(6), γ = 85.511(6)°, V = 1203.07(18) Å3, and Z = 2. The structure (R1 = 0.0377 for 1935 I = 2σI) contains [(UO2)2(SO4)8]4– uranyl-sulfate clusters that are linked into a band by bridging LiO4 tetrahedra. The bands are linked through peripheral SO4 tetrahedra forming a thick heteropolyhedral layer. Channels within the layers contain a K site, while an additional K site, six Na sites, and an SO3OH group occupy the space between the heteropolyhedral layers.
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Meyrowitzite, Ca(UO2)(CO3)2⋅5H2O, is a new mineral species from the Markey mine, Red Canyon, San Juan County, Utah, U.S.A. It is a secondary phase found on calcite-veined asphaltum in association with gypsum, markeyite, and rozenite. Meyrowitzite occurs as blades up to about 0.2 mm in length, elongate on [010], flattened on {100}, and exhibiting the forms {100}, {001}, {101}, {110}, and {011}. The mineral is yellow and transparent with vitreous luster and very pale yellow streak. Fluorescence under a 405 nm laser is from weak greenish yellow to moderate greenish blue. The Mohs hardness is ca. 2, tenacity is brittle, fracture is irregular, and there is one perfect cleavage, {101}. The measured density is 2.70(2) g/cm3. The mineral is optically biaxial (+) with α = 1.520(2), β = 1.528(2), and γ = 1.561(2) (white light). The 2V(meas) = 53.0(6)°; weak dispersion, r > ν; optical orientation: Z = b, Y ^ a = 19° in obtuse β; pleochroism pale yellow, X ≈ Y < Z. Electron microprobe analyses provided the empirical formula Ca0.94(U1.00O2)(CO3)2⋅5(H2.02O) on the basis of U = 1 and O = 13 apfu, as indicated by the crystal structure determination. Meyrowitzite is monoclinic, P21/n, a = 12.376(3), b = 16.0867(14), c = 20.1340(17) Å, β = 107.679(13)°, V = 3819.3(12) Å3, and Z = 12. The structure (R1 = 0.055 for 3559 Io > 2σI) contains both UO7 pentagonal bipyramids and UO8 hexagonal bipyramids, the latter participating in uranyl tricarbonate clusters (UTC). The two kinds of bipyramids and the carbonate groups link to form a novel corrugated heteropolyhedral sheet. This is the first structural characterization of a uranyl-carbonate mineral with a U:C ratio of 1:2. Meyrowitzite is apparently dimorphous with zellerite.
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Uranyl
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Abstract Hansblockite, ideally (Cu,Hg)(Bi,Pb)Se 2 , is a new selenide from the El Dragón mine, Bolivia. It typically occurs in thin subparallel plates intergrown with two unnamed Cu–Hg–Pb–Bi–Se species, clausthalite, Corich penroseite and petrovicite.It also forms subhedral to anhedral grains up to 150 μm long and 50 μm wide. Hansblockite is non-fluorescent, black and opaque with a metallic lustre and black streak. It is brittle, with an irregular fracture and no obvious parting and cleavage. The VHN 20 values range from37 to 50 (mean 42) kg mm –2 (Mohs hardness 2–2½). In plane-polarized incident light, hansblockite is cream to light grey in colour, weakly bireflectant and weakly pleochroic from greyish cream to cream. Under crossed polars, hansblockite is weakly anisotropic withkhaki to pale blue rotation tints. The reflectance values in air for the Commission on Ore Mineralogy (COM) standard wavelengths are: 47.3–48.1 (470 nm), 47.4–49.9 (546 nm), 47.1–49.0 (589 nm) and 46.6–48.5 (650 nm). The mean composition is Cu 9.31, Ag 0.73, Hg 11.43,Pb 3.55, Ni 0.17, Co 0.03, Bi 31.17, Se 34.00, total 100.39 wt.%. The mean empirical formula (based on 4 apfu) is (Cu 0.68 Hg 0.27 Ag 0.03 Ni 0.01 ) ∑=0.99 (Bi 0.69 Pb 0.31 ) ∑=1.00 Se 2.01 . The simplifiedformula is (Cu,Hg) (Bi,Pb)Se 2 . Hansblockite is monoclinic, space group P 2 1 / c , with a = 6.853(1), b = 7.635(1), c = 7.264(1) Å, β = 97.68(1)°, V = 376.66(9) Å 3 and Z = 4. Density is 8.26 gcm –3 . The five strongest powder X-ray diffraction lines [ d in Å ( I / I 0 ) ( hkl )] are: 3.97 (90) (111), 3.100 (40) (121), 2.986 (100) (211), 2.808 (50) (112) and 2.620 (50) (022). Hansblockite represents the monoclinic polymorph ofgrundmannite, CuBiSe 2 , with Hg and Pb being essential in stabilizing the monoclinic structure via the coupled substitution Cu + + Bi 3+ ⇔ Hg 2+ + Pb 2+ . The mineral name is in honour of Hans Block (1881–1953), in recognition of hisimportant role in boosting Bolivian ore mining.
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Monoclinic crystal system
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Selenide
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