Maneckiite, ideally NaCa2Fe2+2(Fe3+Mg)Mn2(PO4)6(H2O)2, a new phosphate mineral of the wicksite supergroup from the Michałkowa pegmatite, Góry Sowie Block, southwestern Poland

2017 ◽  
Vol 81 (3) ◽  
pp. 723-736 ◽  
Author(s):  
Adam Pieczka ◽  
Frank C. Hawthorne ◽  
Bożena Gołębiowska ◽  
Adam Włodek ◽  
Anna Grochowina
Keyword(s):  
Outer Zone ◽  
Unit Cell Parameters ◽  
Calculated Density ◽  
Cell Parameters ◽  
Phosphate Mineral ◽  
Dark Colour ◽  
Mohs Hardness ◽  
Sw Poland ◽  
Dark Green ◽  
Dark Blue

AbstractManeckiite, ideally NaCa2Fe22þ (Fe3+Mg)Mn2(PO4)6(H2O)2, was found in a pegmatite at Michałkowa, Góry Sowie Block, SW Poland. The mineral forms subhedral and anhedral crystals ~150 μm × 150 μm in the outer zone of phosphate nodules, where it is associated with fluorapatite, wolfeite, Ca-rich graftonite and alluaudite-group minerals. Maneckiite is transparent, dark brown, with a colourless streak and vitreous lustre, brittle, and has a good cleavage // {010}, a splintery fracture and a Mohs hardness of ~5. The calculated density is 3.531 g cm–3. Maneckiite is pleochroic: α = dark green, β = dark blue/green, γ = light brown/tan, biaxial (+) with refractive indices α = 1.698(2), β = 1.706(2), γ = 1.727(2) and birefringence Δ = ~0.03; 2Vmeas. = 65.9 (1.5)° and 2Vcalc. = 64°, dispersion is obscured by the dark colour, and optical orientation X//a, Y//b, Z//c. Maneckite is orthorhombic (Pcab) and has unit-cell parameters a = 12.526(4) Å, b = 12.914(5) Å, c = 11.664(4) Å and V = 1886.8(5) Å3. The strongest reflections are (dhkl in Å; I; hkl): 2.759, 100, 402; 2.916, 78, 004; 3.020, 68, 401; 2.844, 35, 014; 2.869, 31, 240; 2.825, 30, 042. Maneckiite has the wicksite structure and is its M(3)Mn-analogue. The mineral crystallized as a product of Na- and Ca-metasomatism induced by a HT fluid in the presence of Al3+ from a neighbouring aluminosilicate melt. A Gladstone-Dale index, 0.027, places maneckiite in the category ‘excellent’.

scholarly journals Żabińskiite, ideally Ca(Al0.5Ta0.5)(SiO4)O, a new mineral of the titanite group from the Piława Górna pegmatite, the Góry Sowie Block, southwestern Poland

2017 ◽  
Vol 81 (3) ◽  
pp. 591-610 ◽  
Author(s):  
Adam Pieczka ◽  
Frank C. Hawthorne ◽  
Chi Ma ◽  
George R. Rossman ◽  
Eligiusz Szełęg ◽  
...  
Keyword(s):  
Group Symmetry ◽  
New Mineral ◽  
Synthetic Material ◽  
Unit Cell Parameters ◽  
Calculated Density ◽  
Triclinic Space Group ◽  
Cell Parameters ◽  
Mohs Hardness ◽  
Sw Poland ◽  
Lower Silesia

AbstractŻabińskiite, ideally Ca(Al0.5Ta0.5)(SiO4)O, was found in a Variscan granitic pegmatite at Piława Górna, Lower Silesia, SW Poland. The mineral occurs along with (Al,Ta,Nb)- and (Al,F)-bearing titanites, a pyrochlore-supergroupmineral and a K-mica in compositionally inhomogeneous aggregates, ∼120 μm × 70 μm in size, in a fractured crystal of zircon intergrown with polycrase-(Y) and euxenite-(Y). Żabińskiite is transparent, brittle, brownish, with a white streak, vitreous lustre and a Mohs hardness of ∼5. The calculated density for the refined crystal is equal to 3.897 g cm–3, but depends strongly on composition. The mineral is non-pleochroic, biaxial (–), with mean refractive indices ≥1.89. The (Al,Ta,Nb)-richest żabińskiite crystal,(Ca0.980Na0.015)∑=0.995(Al0.340Fe3+0.029Ti0.298V0.001Zr0.001Sn0.005Ta0.251Nb0.081)∑=1.005[(Si0.988Al0.012)O4.946F0.047(OH)0.007)∑=5.000];60.7 mol.% Ca[Al0.5(Ta,Nb)0.5](SiO4)O; is close in composition to previously described synthetic material. Żabińskiite is triclinic (space group symmetry A1) and has unit-cell parameters a = 7.031(2) Å, b = 8.692(2) Å,c = 6.561(2) Å, α = 89.712(11)°, β = 113.830(13)°, γ = 90.352(12)° and V = 366.77 (11) Å3. It is isostructural with triclinic titanite and bond-topologically identical with titanite and other minerals of the titanite group.Żabińskiite crystallized along with (Al,Ta,Nb)-bearing titanites at increasing Ti and Nb, and decreasing Ta activities, almost coevally with polycrase-(Y) and euxenite-(Y) from Ca-contaminated fluxed melts or early hydrothermal fluids.

Kummerite, Mn2+Fe3+Al(PO4)2(OH)2·8H2O, a new laueite-group mineral from the Hagendorf Süd pegmatite, Bavaria, with ordering of Al and Fe3+

2016 ◽  
Vol 80 (7) ◽  
pp. 1243-1254 ◽  
Author(s):  
I. E. Grey ◽  
E. Keck ◽  
W. G. Mumme ◽  
A. Pring ◽  
C. M. Macrae ◽  
...  
Keyword(s):  
Electron Microprobe ◽  
Empirical Formula ◽  
X Ray Diffraction ◽  
Unit Cell Parameters ◽  
Calculated Density ◽  
Group Mineral ◽  
X Ray ◽  
Cell Parameters ◽  
Octahedral Sites ◽  
Phosphate Mineral

AbstractKummerite, ideally Mn2+Fe3+A1(PO4)2(OH)2.8H2O, is a new secondary phosphate mineral belonging to the laueite group, from the Hagendorf-Süd pegmatite, Hagendorf, Oberpfalz, Bavaria, Germany. Kummerite occurs as sprays or rounded aggregates of very thin, typically deformed, amber yellow laths. Cleavage is good parallel to ﹛010﹜. The mineral is associated closely with green Zn- and Al-bearing beraunite needles. Other associated minerals are jahnsite-(CaMnMn) and Al-bearing frondelite. The calculated density of kummerite is 2.34 g cm 3. It is optically biaxial (-), α= 1.565(5), β = 1.600(5) and y = 1.630(5), with weak dispersion. Pleochroism is weak, with amber yellow tones. Electron microprobe analyses (average of 13 grains) with H2O and FeO/Fe2O3 calculated on structural grounds and normalized to 100%, gave Fe2O3 17.2, FeO 4.8, MnO 5.4, MgO 2.2, ZnO 0.5, Al2O3 9.8, P2O5 27.6, H2O 32.5, total 100 wt.%. The empirical formula, based on 3 metal apfu is (Mn2+0.37Mg0.27Zn0.03Fe2+0.33)Σ1.00(Fe3+1.06Al0. 94)Σ2.00PO4)1.91(OH)2.27(H2O)7.73. Kummerite is triclinic, P1̄, with the unit-cell parameters of a = 5.316(1) Å, b =10.620(3) Å , c = 7.118(1) Å, α = 107.33(3)°, β= 111.22(3)°, γ = 72.22(2)° and V= 348.4(2) Å3. The strongest lines in the powder X-ray diffraction pattern are [dobs in Å(I) (hkl)] 9.885 (100) (010); 6.476 (20) (001); 4.942 (30) (020); 3.988 (9) (̄110); 3.116 (18) (1̄20); 2.873 (11) (1̄21). Kummerite is isostructural with laueite, but differs in having Al and Fe3+ ordered into alternate octahedral sites in the 7.1 Å trans-connected octahedral chains.

Bassoite, SrV3O7·4H2O, a new mineral from Molinello mine, Val Graveglia, eastern Liguria, Italy

2011 ◽  
Vol 75 (5) ◽  
pp. 2677-2686 ◽  
Author(s):  
L. Bindi ◽  
C. Carbone ◽  
R. Cabella ◽  
G. Lucchetti
Keyword(s):  
Structure Refinement ◽  
Full Professor ◽  
New Mineral ◽  
Monoclinic Space Group ◽  
Calculated Density ◽  
X Ray ◽  
Cell Parameters ◽  
Mohs Hardness ◽  
Dark Green ◽  
The University

AbstractBassoite, ideally SrV3O7·4H2O, is a new mineral from the Molinello manganese mine, Val Graveglia. eastern Liguria, northern Apennines, Italy. It occurs as black euhedral to subhedral grains up to 400 urn across, closely associated with rhodonite, quartz and braunite. Bassoite is opaque with a sub-metallic lustre and a black streak. It is brittle and neither fracture nor cleavage was observed; the Vickers micro-hardness (VHN100) is 150 kg/mm (range 142—165; corresponding to a Mohs hardness of 4—41/2). The calculated density is 2.940 g/cm3 (on the basis of the empirical formula and X-ray single-crystal data). Bassoite is weakly bireflectant and very weakly pleochroic from grey to a dark green. Internal reflections are absent. The mineral is anisotropic, without characteristic rotation tints. Reflectance percentages (Rmin and Rmax) for the four standard COM wavelengths are 18.5%, 19.0% (471.1 nm); 17.2%, 17.8% (548.3 nm); 16.8%, 17.5% (586.6 nm) and 16.2%, 16.8% (652.3 nm), respectively.Bassoite is monoclinic, space group P21/m, with unit-cell parameters: a = 5.313(3) Å, b = 10.495(3) Å, c = 8.568(4) Å, β = 91.14(5)°, V= 477.7(4) Å3, a:b:c = 0.506:1:0.816, and Z = 2. The crystal structure was refined to R1 = 0.0209 for 1148 reflections with Fo > 4σ(Fo) and it consists of layers of VO5 pyramids (with vanadium in the tetravalent state) pointing up and down alternately with Sr between the layers (in nine-fold coordination). The nine most intense X-ray powder-diffraction lines [d in Å (I/I0) (hkt)] are: 8.5663 (100) (001); 6.6363 (14) (011); 3.4399 (14) (1̄21); 3.4049 (17) (121); 2.8339 (15) (1̄22); 2.7949 (11) (122); 2.6550 (15) (200); 2.6237 (11) (040) and 1.8666 (15) (240). Electron microprobe analyses produce a chemical formula (Sr0.97Ca0.02Na0.01)V3.00O74H20, on the basis of 2(Sr+Ca+Na) = 1, taking the results of the structure refinement into account. The presence of water molecules was confirmed by micro-Raman spectroscopy. The name honours Riccardo Basso (b. 1947), full professor of Mineralogy and Crystallography at the University of Genova. The new mineral and mineral name have been approved by the Commission on New Minerals, Nomenclature and Classification, IMA (2011-028).

New minerals with modular structure derived from hatrurite from the pyrometamorphic rocks. Part IV: Dargaite, BaCa12(SiO4)4(SO4)2O3, from Nahal Darga, Palestinian Autonomy

2018 ◽  
Vol 83 (1) ◽  
pp. 81-88 ◽  
Author(s):  
Irina O. Galuskina ◽  
Frank Gfeller ◽  
Evgeny V. Galuskin ◽  
Thomas Armbruster ◽  
Yevgeny Vapnik ◽  
...  
Keyword(s):  
Unit Cell Parameters ◽  
Calculated Density ◽  
X Ray ◽  
Cell Parameters ◽  
Holotype Specimen ◽  
Mineral Associations ◽  
Mohs Hardness ◽  
Formation Conditions ◽  
Additional Member ◽  
By Products

AbstractDargaite, ideally BaCa12(SiO4)4(SO4)2O3, is an additional member of the arctite group belonging to minerals with a modular intercalated antiperovskite structure derived from hatrurite. The holotype specimen was found at a small outcrop of larnite pseudoconglomerates in the Judean Mts, West Bank, Palestinian Autonomy. Larnite, fluorellestadite–fluorapatite, brownmillerite, fluormayenite–fluorkyuygenite and ye'elimite are the main minerals of the holotype specimen; ternesite, shulamitite and periclase are noted rarely. Dargaite, nabimusaite and gazeevite occur in linear zones with higher porosity within larnite rocks. Pores are filled with ettringite and Ca-hydrosilicates, less commonly with gibbsite, brucite, baryte, katoite and calciolangbeinite. Dargaite is colourless, transparent with a white streak and has a vitreous lustre. It exhibits pronounced parting and imperfect cleavage along (001). Mohs’ hardness is ~4.5–5.5. The empirical formula is (Ba0.72K0.24Na0.04)Σ1(Ca11.95Mg0.04Na0.01)Σ12([SiO4]0.91 [PO4]0.05[AlO4]0.03[Ti4+O4]0.01)Σ4([SO4]0.84[PO4]0.14[CO3]0.02)Σ2(O2.54F0.46)Σ3. Dargaite is trigonal R$\overline 3 $m, the unit-cell parameters are: a = 7.1874(4) Å, c = 41.292(3) Å, V = 1847.32(19) Å3 and Z = 3. The crystal structure of dargaite was refined from X-ray single-crystal data to R1 = 3.79%. The calculated density is 3.235 g cm–3. The following main Raman bands are distinguished on the holotype dargaite (cm–1): 122, 263, 323, 464, 523, 563, 641 and 644, 829 and 869, 947, 991 and 1116. The formation conditions of dargaite are linked to the local occurrence of pyrometamorphic by-products (gases, fluids and melts) transforming earlier mineral associations at ~900°C.

Daliranite, PbHgAs2S6, a new sulphosalt from the Zarshouran Au-As deposit, Takab region, Iran

2009 ◽  
Vol 73 (5) ◽  
pp. 871-881 ◽  
Author(s):  
W. H. Paar ◽  
A. Pring ◽  
Y. Moëlo ◽  
C. J. Stanley ◽  
H. Putz ◽  
...  
Keyword(s):  
Late Phase ◽  
Electron Diffraction Study ◽  
Ore Deposits ◽  
Unit Cell Parameters ◽  
Calculated Density ◽  
Crystallization Sequence ◽  
X Ray ◽  
Cell Parameters ◽  
Mohs Hardness ◽  
The Town

AbstractDaliranite, ideally PbHgAs2S6, a new sulphosalt from the Zarshouran Au-As deposit, Takab region, Iran, occurs as a rare sulphosalt species at the Carlin-type Zarshouran Au-As deposit North of the town of Takab in the Province of West Azarbaijan, Iran. The new species is associated with orpiment, rarely with galkhaite, hutchinsonite and cinnabar. The strongly silicified matrix of the specimens has veinlets of sphalerite, with rare inclusions of galena and various (Cu)-Pb-As(Sb) sulphosalts. Daliranite occurs as matted nests of acicular and flexible fibres up to 200 μm in length and a width less than a few μm. The colour is orange-red with a pale orange-red streak and the lustre is adamantine. The mineral is transparent and does not fluoresce. The Mohs hardness is <2. Electron microprobe analyses give the empirical formula Pb0.95Tl0.01Hg1.04As2.10S5.91, ideally PbHgAs2S6, a new sulphosalt from the Zarshouran Au-As deposit, Takab region, Iran; the calculated density is 5.93 g cm–3. Unit-cell parameters were determined by an electron-diffraction study and refined from X-ray powder data. Daliranite is monoclinic primitive with a = 19.113(5) Å, b = 4.233(2) Å, c = 22.958(8) Å, β = 114.78(5)°, V = 1686.4 Å3 and Z = 8, a:b:c = 4.515:1:5.424, space group P2, Pm or P2/m. The strongest X-ray powder-diffraction lines [d in Å, (I), (hkl)] are: 8.676, (80), (200); 4.654, (50), (401); 3.870, (40), (211); 3.394, (50), (113); 3.148, (40b), (602); 2.892, (50), (600); 2.724, (100), (703); 2.185, (50), (319). The formula shows a sulphur excess which may correspond to S—S bonding (persulphide). The new sulphosalt is a late phase in the crystallization sequence, and was formed after orpiment, contemporaneously with quartz II, at a temperature between 157 and 193°C. The name honours Dr Farahnaz Daliran (University of Karlsruhe, Germany) in recognition of her outstanding contributions to research on ore deposits, especially Au, Zn and Fe, in Iran.

Kurilite – Ag8Te3Se – a new mineral from the Prasolovskoe deposit, Kuril islands, Russian Federation

2010 ◽  
Vol 74 (3) ◽  
pp. 463-468 ◽  
Author(s):  
V. A. Kovalenker ◽  
O. Yu. Plotinskaya ◽  
C. J. Stanley ◽  
A. C. Roberts ◽  
A. M. McDonald ◽  
...  
Keyword(s):  
Russian Federation ◽  
Empirical Formula ◽  
Polarized Light ◽  
New Mineral ◽  
Unit Cell Parameters ◽  
Calculated Density ◽  
X Ray ◽  
Cell Parameters ◽  
Kunashir Island ◽  
Mohs Hardness

AbstractKurilite, with the simplified formula, Ag8Te3Se, is a new mineral from the Prasolovskoe epithermal Au-Ag deposit, Kunashir Island, Kuril arc, Russian Federation. It occurs as aggregates up to 2 mm in size, composed of brittle xenomorphic grains, up to several μm in size, in quartz, associated with tetrahedrite, hessite, sylvanite and petzite. Kurilite is opaque, grey, with a metallic lustre and a black streak. Under plane-polarized light, kurilite is white with no observed bireflectance, cleavage, or parting observed. Under crossed polars it appears isotropic without internal reflections. Reflectance values in air and in oil, are tabulated. It has a mean VHN (25 g load) of 99.9 kg/mm2 which equates roughly to a Mohs hardness of 3. Electron microprobe analyses yield a mean composition of Ag 63.71, Au 0.29, Te 29.48, Se 5.04, S 0.07, total 98.71 wt.%. The empirical formula (based on 12 atoms) is (Ag7.97Au0.02)Σ7.99Te3.00(Se0.86Te0.12S0.03)Σ1.01. The calculated density is 7.799 g/cm3 (based on the empirical formula and unit-cell parameters refined from single-crystal data). Kurilite is rhombohedral, R3 or , a 15.80(1), c 19.57(6) Å, V 4231(12)Å3, c:a 1.2386, Z = 15. Its crystal structure remains unsolved. The seven strongest lines of the X-ray powder-diffraction pattern [d in Å (I)(hkl)] are: 3.727(20)(131), 2.996(50)(232), 2.510(30)(226,422), 2.201(100)(128,416,342), 2.152(20)(603), 2.079(30)(253), 2.046(20)(336,434). The mineral is named after the locality.

Oxyplumboroméite, Pb2Sb2O7, a new mineral species of the pyrochlore supergroup from Harstigen mine, Värmland, Sweden

2013 ◽  
Vol 77 (7) ◽  
pp. 2931-2939 ◽  
Author(s):  
U. Hålenius ◽  
F. Bosi
Keyword(s):  
Crystal Structure ◽  
Structure Refinement ◽  
New Mineral ◽  
Crystal Structure Refinement ◽  
Unit Cell Parameters ◽  
Calculated Density ◽  
X Ray ◽  
Cell Parameters ◽  
New Mineral Species ◽  
Mohs Hardness

AbstractOxyplumboroméite, Pb2Sb2O7, is a new mineral of the roméite group of the pyrochlore supergroup (IMA 2013-042). It is found together with calcite and leucophoenicite in fissure fillings in tephroite skarn at the Harstigen mine, Värmland, Sweden. The mineral occurs as yellow to brownish yellow rounded grains or imperfect octahedra. Oxyplumboroméite has a Mohs hardness of ∼5, a calculated density of 6.732 g/cm3 and is isotropic with a calculated refractive index of 2.061. Oxyplumboroméite is cubic, space group Fdm, with the unit-cell parameters a = 10.3783(6) Å, V = 1117.84(11) Å3 and Z = 8. The strongest five X-ray powder-diffraction lines [d in Å(I)(hkl)] are: 2.9915(100)(222), 2.5928(32)(400), 1.8332(48)(440), 1.5638(38)(622) and 1.1900(12)(662). The crystal structure of oxyplumboroméite was refined to an R1 index of 3.02% using 160 unique reflections collected with MoKα radiation. Electron microprobe analyses in combination with crystal-structure refinement, infrared, Mössbauer and electronic absorption spectroscopy resulted in the empirical formula A(Pb0.92Ca0.87Mn0.09Sr0.01Na0.05)Σ1.93B(Sb1.73Fe3+0.27)Σ2.00X+Y[O6.64(OH)0.03]Σ6.67. Oxyplumboroméite is the Pb analogue of oxycalcioroméite, ideally Ca2Sb2O7.

Huenite, Cu4Mo3O12(OH)2, a New Copper-molybdenum Oxy-hydroxide Mineral from the San Samuel Mine, Carrera Pinto, Cachiyuyo De Llampos District, CopiapÓ Province, Atacama Region, Chile

2019 ◽  
Vol 57 (4) ◽  
pp. 467-474
Author(s):  
Pietro Vignola ◽  
Nicola Rotiroti ◽  
G. Diego Gatta ◽  
Andrea Risplendente ◽  
Frédéric Hatert ◽  
...  
Keyword(s):  
Close Association ◽  
Short Wave ◽  
Formula Unit ◽  
X Ray Diffraction ◽  
Unit Cell Parameters ◽  
Calculated Density ◽  
X Ray ◽  
Cell Parameters ◽  
Long Wave ◽  
Mohs Hardness

Abstract Huenite, Cu4Mo3O12(OH)2, is a new copper and molybdenum oxy-hydroxide mineral found in the San Samuel Mine, Carrera Pinto, Cachiyuyo de Llampos district, Copiapó Province, Atacama Region, Chile. This new species forms flattened orthorhombic prisms up to 60–70 μm in size, weakly elongated along [001]. Huenite crystals were found on fractured surfaces of a quartz breccia, forming aggregates 1 mm in diameter in close association with lindgrenite, gypsum, dark grayish-brown tourmaline, and an unknown pale purple phase. The color is very dark reddish-brown, with a strong vitreous to adamantine luster. Its streak is pale reddish-brown to pinkish. The mineral is brittle with an irregular fracture and a Mohs hardness of 3.5–4 with a good cleavage on {010}. Its calculated density is 5.1 g/cm3. The calculated refractive index is 2.18. Huenite is non-fluorescent under 254 nm (short wave) and 366 nm (long wave) ultraviolet light. The empirical formula, calculated on the basis of 3 (Mo+S+Si) atoms per formula unit, is (Cu3.519Fe2+0.403)Σ3.922(Mo2.907S0.090Si0.003)Σ3.000O12·(OH)2.229, with H2O content calculated for a total of 100 wt.%. Huenite is trigonal, with space group P31/c and unit-cell parameters a = 7.653(5) Å, c = 9.411(6) Å, and V = 477.4(5) Å3 for Z = 2. The eight strongest measured powder X-ray diffraction lines are: [d in Å, (I/I0), (hkl)]: 2.974 (100) (112), 1.712 (59.8) (132), 3.810 (50.6) (110), 2.702 (41.2) (022), 2.497 (38.1) (120), 1.450 (37.2) (134), 6.786 (24.9) (010), and 5.374 (24.5) (011). The mineral, which has been approved by the CNMNC under number IMA 2015-122, is named in honor of Edgar Huen.

Twinning and incommensurate modulation in baumoite, Ba0.5[(UO2)3O8Mo2(OH)3](H2O)~3, the first natural Ba uranyl molybdate

2019 ◽  
Vol 83 (4) ◽  
pp. 507-514
Author(s):  
Peter Elliott ◽  
Jakub Plášil ◽  
Václav Petříček ◽  
Jiří Čejka ◽  
Luca Bindi
Keyword(s):  
South Australia ◽  
New Mineral ◽  
X Ray Diffraction ◽  
Unit Cell Parameters ◽  
Calculated Density ◽  
X Ray ◽  
Cell Parameters ◽  
Orange Yellow ◽  
Incommensurate Modulation ◽  
Mohs Hardness

ABSTRACTBaumoite, Ba0.5[(UO2)3O8Mo2(OH)3](H2O)~3, is a new mineral found near Radium Hill, South Australia, where it occurs in a granite matrix associated with baryte, metatorbernite, phurcalite and kaolinite. Baumoite forms thin crusts of yellow to orange–yellow tabular to prismatic crystals. The mineral is translucent with a vitreous lustre and pale yellow streak. Crystals are brittle, the fracture is uneven and show one excellent cleavage. The Mohs hardness is ~2½. The calculated density is 4.61 g/cm3. Optically, baumoite crystals are biaxial (–), with α = 1.716(4), β = 1.761(4), γ = 1.767(4) (white light); and 2Vcalc= 42.2°. Electron microprobe analyses gave the empirical formula Ba0.87Ca0.03Al0.04U2.97Mo2.02P0.03O22H11.99, based on 22 O atoms per formula unit. The eight strongest lines in the powder X-ray diffraction pattern are [dobsÅ (I) (hkl)]: 9.175(39)(12${\bar 1}$), 7.450(100)(020), 3.554(20)(221), 3.365(31)(004, 202), 3.255(31)(123, 30${\bar 2}$), 3.209(28)(12${\bar 4}$), 3.067(33)(30${\bar 3}$, 222, 32${\bar 2}$) and 2.977(20)(142). Single-crystal X-ray studies (R1= 5.85% for 1892 main reflections) indicate that baumoite is monoclinic, superspace groupX2/m(a0g)0swithX= (0,½,0,½), with unit-cell parameters:a= 9.8337(3),b= 15.0436(5),c= 14.2055(6) Å, β = 108.978(3)°,V= 1987.25(13) Å3andZ= 4. The crystal structure is twinned and incommensurately modulated and is based upon sheets of U6+and Mo6+polyhedra of unique topology. Four independent cationic sites partially occupied by Ba atoms are located between the sheets, together with H2O molecules.

Vaughanite, TlHgSb4S7, a new mineral from Hemlo, Ontario, Canada

1989 ◽  
Vol 53 (369) ◽  
pp. 79-83 ◽  
Author(s):  
Donald C. Harris ◽  
Andrew C. Roberts ◽  
Alan J. Criddle
Keyword(s):  
Polarized Light ◽  
New Mineral ◽  
Drill Core ◽  
Unit Cell Parameters ◽  
Calculated Density ◽  
X Ray ◽  
Cell Parameters ◽  
Arterial Blood ◽  
Mohs Hardness ◽  
Simplified Formula

AbstractVaughanite, idealized formula T1HgSb4S7, is a very rare primary constituent of the Golden Giant orebody of the Hemlo gold deposit, Hemlo, Ontario, Canada. It was found in two polished sections from one drill core; as a 450 by 300 µm aggregate associated with pääkkönenite, stibnite, realgar, and native arsenic; and as a 40 µm anhedral grain associated with stibarsen and chalcostibite. Vaughanite is opaque with a metallic lustre and a black streak. No cleavage was observed but parting, produced by indentation, was detected as a series of weak parallel traces. It is brittle, with an even, occasionally arcuate, fracture. VHN25 is 100–115, mean 104. Mohs hardness (calc.) = 3−3½. In refected plane-polarized light in air the bireflectance is weak to moderate; the pleochroism is also weak, from a somewhat greenish grey to slightly darker bluish grey. Anisotropism is moderate to strong, with rotation tints in shades of green, yellow, purplish brown to brown. Reflectance spectra and colour values are tabulated. The colour in air is light grey. Internal reflections are rare but are arterial-blood-red on indentation fractures. X-ray studies have shown that vaughanite is triclinic with refined unit-cell parameters a 9.012 (3), b 13.223 (3), c 5.906 (2) Å, α 93.27 (3)°, β 95.05 (4)°, γ 109.16 (3)°, V 659.46 (80) Å3, a:b:c = 0.6815 : 1 : 0.4466 and Z = 2. The space group choices are P1 (1) or (2), diffraction aspect P*. The five strongest lines in the X-ray powder pattern [d in Å (l) (hkl)] are: 4.343 (30) (), 4.204 (100) (), 3.313 (60) (130), 2.749 (40) (, 131) and 2.315 (30) (, 122). The average of five electron microprobe analyses gave T1 18.3 (2), Hg 17.5 (2), Sb 43.4 (3), As 1.1 (1), S 20.5 (5), total 100.8 wt. %, corresponding, on the basis of total atoms = 13, to T10.98Hg0.95(Sb3.90As0.17)Σ4.07S7.00. The calculated density is 5.56 g/cm3 for the empirical formula and 5.62 g/cm3 for the simplified formula. The mineral is named for Professor David J. Vaughan.

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