Hansblockite, (Cu,Hg)(Bi,Pb)Se2, the monoclinic polymorph of grundmannite: a new mineral from the Se mineralization at El Dragón (Bolivia)
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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.Keywords:
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Monoclinic crystal system
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Selenide
Abstract Tsugaruite, Pb 4 As 2 S 7 , is a new Pb-As sulphosalt from the Yunosawa mine, Aomori Prefecture, northern Japan. X-ray studies indicated it to be orthorhombic Pnn 2 or Pnnm , a 15.179(1), b 38.195(1), c 8.0745(1) Å, Z = 16 [Pb 4 As 2 S 7 ] with a subcell with c′ = 1/2 c . The six strongest diffractions in the X-ray powder pattern [d (in Å), ( I ), ( hkl )] are: 4.47 (30) (340), 3.705 (34) (1.10.0), 3.395 (100) (450), 2.870 (34) (192), 2.819 (53) (550), and 2.739 (48) (560, 2.13.0). The average of seven electron microprobe analyses gave Pb 68.70, Tl 0.13, As 12.45, S 18.64, total 99.92 wt.%. The empirical formula calculated on the basis of total atoms = 13 is Pb 3.99 Tl 0.01 As 2.00 S 7.00 , corresponding to the ideal formula Pb 4 As 2 S 7 . The calculated density is 6.83 g/cm 3 for the ideal formula. Tsugaruite is opaque with a metallic lustre and lead-grey streak. No cleavage was observed. It is brittle with uneven fracture. VHN 25 is 75.4–94.9 kg/mm 2 , mean 86.4 ( n ) = 4), corresponding to 2.5–3 in Mohs' hardness scale. In reflected plane-polarised light in air, it is white with a greenish tint, more greenish than jordanite. Bireflectance and pleochroism are weak, weaker than those of jordanite; and anisotropism is weak to moderate, weaker than that of jordanite. No internal reflections. The reflectance spectra are tabulated in the text. Tsugaruite was found in a thin baryte veinlet exposed in the wall of a small open cut of the Yunosawa mine. It forms radiating groups of long tabular tapering crystals elongated along c and tabular to b , up to 0.04 mm wide and 2 mm long. The associated minerals are jordanite, which formed earlier than tsugaruite, and galena. The chemical similarity of tsugaruite and jordanite and their intergrown character indicates that earlier jordanite analyses may also include analyses of tsugarite.
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Abstract Bicapite, KNa2Mg2(H2PV145+O42)·25H2O, is a new mineral species (IMA2018-048) discovered at the Pickett Corral mine, Montrose County, Colorado, U.S.A. Bicapite occurs as square tablets up to about 0.2 mm on edge on montroseite-corvusite-bearing sandstone. Crystals are dark red-brown, often appearing black. The streak is orange, and the luster is vitreous. Bicapite is brittle, has a Mohs hardness of 1½, and displays one excellent cleavage on {100}. The measured density is 2.44(2) g/cm3. Bicapite is uniaxial (+), ω = 1.785(5), ε ≈ 1.81 (white light); pleochroism is red-brown; E > O, slight. The electron probe microanalysis and results of the crystal structure determination provided the empirical formula (based on 67 O apfu) (K1.23Na2.23Mg1.48)Σ4.94[H2.51P1.02(V13.915+Mo0.076+)Σ13.98O42]·25H2O. Bicapite is tetragonal, I4/m, with a = 11.5446(12) Å, c = 20.5460(14) Å, V = 2738.3(6) Å3, and Z = 2. The strongest four lines in the diffraction pattern are [d in Å (I) (hkl)]: 10.14 (100) (002,101); 2.978 (29) (134,206); 2.809 (11) (305); and 2.583 (11) (420,008). The atomic arrangement of bicapite was solved and refined to R1 = 0.0465 for 1008 independent reflections with I > 2σI. The structural unit is a [H2PV125+O40(V5+O)2]7– heteropolyanion composed of 12 distorted VO6 octahedra surrounding a central PO4 tetrahedron and capped on opposite sides by two VO5 square pyramids; the structural unit is a modification of the α-isomer of the Keggin anion, [XM12O40]n–. Charge balance in the structure is maintained by the [KNa2Mg2(H2O)25]7+ interstitial complex. The name bicapite is in recognition of this being the only known mineral with a structure based on a bicapped Keggin anion. The discovery of bicapite and numerous other natural polyoxometalate compounds in the Colorado Plateau uranium/vanadium deposits make that the most productive region found to date for naturally occurring polyoxometalate compounds.
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Diopside
Tourmaline
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Titanite
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Acicular
Ettringite
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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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The new mineral nöggerathite-(Ce) was discovered in a sanidinite volcanic ejectum from the Laach Lake (Laacher See) paleovolcano in the Eifel region, Rhineland-Palatinate, Germany. Associated minerals are sanidine, dark mica, magnetite, baddeleyite, nosean, and a chevkinite-group mineral. Nöggerathite-(Ce) has a color that ranges from brown to deep brownish red, with adamantine luster; the streak is brownish red. It occurs in cavities of sanidinite and forms long prismatic crystals measuring up to 0.02 × 0.03 × 1.0 mm, with twins and random intergrowths. Its density calculated using the empirical formula is 5.332 g/cm3. The Vickers hardness number (VHN) is 615 kgf/mm2, which corresponds to a Mohs’ hardness of 5½. The mean refractive index calculated using the Gladstone–Dale equation is 2.267. The Raman spectrum shows the absence of hydrogen-bearing groups. The chemical composition (electron microprobe holotype/cotype in wt %) is as follows: CaO 5.45/5.29, MnO 4.19/4.16, FeO 7.63/6.62, Al2O3 0.27/0.59, Y2O3 0.00/0.90, La2O3 3.17/3.64, Ce2O3 11.48/11.22, Pr2O3 1.04/0.92, Nd2O3 2.18/2.46, ThO2 2.32/1.98, TiO2 17.78/18.69, ZrO2 27.01/27.69, Nb2O5 17.04/15.77, total 99.59/99.82, respectively. The empirical formulae based on 14 O atoms per formula unit (apfu) are: (Ce0.59La0.165Nd0.11Pr0.05)Σ0.915Ca0.82Th0.07Mn0.50Fe0.90Al0.045Zr1.86Ti1.88Nb1.07O14 (holotype), and (Ce0.57La0.19Nd0.12Pr0.05Y0.06)Σ0.99Ca0.79Th0.06Mn0.49Fe0.77Al0.10Zr1.89Ti1.96Nb1.00O14 (cotype). The simplified formula is (Ce,Ca)2Zr2(Nb,Ti)(Ti,Nb)2Fe2+O14. Nöggerathite-(Ce) is orthorhombic, of the space group Cmca. The unit cell parameters are: a = 7.2985(3), b = 14.1454(4), c = 10.1607(4) Å, and V = 1048.99(7) Å3. The crystal structure was solved using single-crystal X-ray diffraction data. Nöggerathite-(Ce) is an analogue of zirconolite-3O, ideally CaZrTi2O7, with Nb dominant over Ti in one of two octahedral sites and REE dominant over Ca in the eight-fold coordinated site. The strongest lines of the powder X-ray diffraction pattern (d, Å (I, %) (hkl)) are: 2.963 (91) (202), 2.903 (100) (042), 2.540 (39) (004), 1.823 (15) (400), 1.796 (51) (244), 1.543 (20) (442), and 1.519 (16) (282), respectively. The type material is deposited in the collections of the Fersman Mineralogical Museum of the Russian Academy of Sciences, Moscow, Russia (registration number 5123/1).
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The new mineral species magnanelliite, K3Fe3+2(SO4)4(OH)(H2O)2, was discovered in the Monte Arsiccio mine, Apuan Alps, Tuscany, Italy. It occurs as steeply terminated prisms, up to 0.5 mm in length, yellow to orange-yellow in color, with a vitreous luster. Streak is pale yellow, Mohs hardness is ca. 3, and cleavage is good on {010}, fair on {100}. The measured density is 2.82(3) g/cm3. Magnanelliite is optically biaxial (+), with α = 1.628(2), β = 1.637(2), γ = 1.665(2) (white light), 2Vmeas = 60(2)°, and 2Vcalc = 59.9°. It exhibits a strong dispersion, r > v. The optical orientation is Y = b, X ^ c ~ 25° in the obtuse angle β. It is pleochroic, with X = orange yellow, Y and Z = yellow. Magnanelliite is associated with alum-(K), giacovazzoite, gypsum, jarosite, krausite, melanterite, and scordariite. Electron microprobe analyses give (wt.%): SO3 47.82, TiO2 0.05, Al2O3 0.40, Fe2O3 25.21, MgO 0.07, Na2O 0.20, K2O 21.35, H2Ocalc 6.85, total 101.95. On the basis of 19 anions per formula unit, assuming the occurrence of one (OH)− and two H2O groups, the empirical chemical formula of magnanelliite is (K2.98Na0.04)Σ3.02(Fe3+2.08Al0.05Mg0.01)Σ2.14S3.93O16(OH)(H2O)2. The ideal end-member formula can be written as K3Fe3+2(SO4)4(OH)(H2O)2. Magnanelliite is monoclinic, space group C2/c, with a = 7.5491(3), b = 16.8652(6), c = 12.1574(4) Å, β = 94.064(1)°, V = 1543.95(10) Å3, Z = 4. Strongest diffraction lines of the observed X-ray powder pattern are [d(in Å), estimated visual intensity, hkl]: 6.9, medium, 021 and 110; 4.91, medium-weak, 022; 3.612, medium-weak, 1 ¯ 32, 023, and 1 ¯ 13; 3.085, strong, 202, 150, and 1 ¯ 33; 3.006, medium, 004, 1 ¯ 51, and 151; 2.704, medium, 152 and 2 ¯ 23; 2.597, medium-weak, 2 ¯ 42; 2.410, medium-weak, 153. The crystal structure of magnanelliite has been refined using X-ray single-crystal data to a final R1 = 0.025, on the basis of 2411 reflections with Fo > 4σ(Fo) and 144 refined parameters. The crystal structure is isotypic with that of alcaparrosaite, K3Ti4+Fe3+(SO)4O(H2O)2.
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Quijarroite, ideally Cu6HgPb2Bi4Se12, is a new selenide species from the El Dragόn mine, Department of Potosí, Bolivia. It most frequently occurs as lath-shaped thin plates (up to 150 µm in length and 20 µm in width) intimately (subparallel) intergrown with hansblockite, forming an angular network-like intersertal texture. Quijarroite is occasionally also present as sub- to anhedral grains up to 200 µm in length and 50 µm in width. It is non-fluorescent, black and opaque with a metallic luster and black streak. It is brittle, with an irregular fracture and no obvious cleavage and parting. In plane-polarized incident light, quijarroite is weakly pleochroic from cream to very slightly more brownish-cream, displaying no internal reflections. Between crossed polars, quijarroite is moderately anisotropic with pale orange-brown to blue rotation tints. Lamellar twinning on {110} is common; parquet twinning occurs rarely. The reflectance values in the air for the COM (Commission on Ore Mineralogy) standard wavelengths (R1 and R2) are: 46.7, 46.8 (470 nm), 47.4, 48.2 (546 nm), 47.1, 48.5 (589 nm), and 46.6, 48.7 (650 nm). Electron-microprobe analyses yielded a mean composition of Cu 13.34, Ag 1.02, Hg 7.67, Pb 16.87, Co 0.03, Ni 0.15, Bi 27.65, Se 33.52, total 100.24 wt %. The mean empirical formula, normalized to 25 apfu (atoms per formula unit), is (Cu5.84Ag0.26)Σ = 6.10(Hg1.06Ni0.07Co0.01)Σ = 1.14Pb2.27Bi3.68Se11.81 (n = 24). The simplified formula is Cu6HgPb2Bi4Se12. Quijarroite is orthorhombic, space group Pmn21, with a = 9.2413(8), b = 9.0206(7), c = 9.6219(8) Å, V = 802.1(1) Å3, Z = 1. The calculated density is 5.771 g·cm−3. The five strongest X-ray powder-diffraction lines (d in Å (I/I0) (hkl)) are: 5.36 (55) (111), 3.785 (60) (211), 3.291 (90) (022), 3.125 (100) (212), and 2.312 (50) (400). The crystal structure of quijarroite can be considered a galena derivative and could be derived from that of bournonite. It is a primary mineral, deposited from an oxidizing low-T hydrothermal fluid at a f S e 2 / f S 2 ratio greater than unity. The new species has been approved by the IMA-CNMNC (2016-052) and is named for the Quijarro Province in Bolivia, in which the El Dragón mine is located.
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Selenide
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