Description and crystal structure of domerockite, Cu4(AsO4)(AsO3OH)(OH)3·H2O, a new mineral from the Dome Rock Mine, South Australia

2013 ◽  
Vol 77 (4) ◽  
pp. 509-522 ◽  
Author(s):  
P. Elliott ◽  
U. Kolitsch ◽  
A. C. Willis ◽  
E. Libowitzky
Keyword(s):  
Crystal Structure ◽  
Structure Refinement ◽  
South Australia ◽  
Direct Methods ◽  
New Mineral ◽  
Calculated Density ◽  
Bluish Green ◽  
Distorted Octahedra ◽  
Mohs Hardness ◽  
Greenish Blue

AbstractDomerockite, Cu4(AsO4)2(AsO3OH)(OH)3·H2O, is a new mineral from the Dome Rock Mine, South Australia. It occurs as aggregates of bluish green, equant to short prismatic and tabular crystals up to 0.3 mm long and 0.2 mm across. Domerockite is translucent, with a vitreous lustre and pale green streak. It displays no fluorescence under UV irradiation. The mineral is brittle with an uneven fracture, a Mohs hardness of ∼3 and a calculated density of 4.44 g/cm3 (based on the structure refinement). Optically, it is biaxial negative, with α = 1.798(4), β = 1.814(4), γ = 1.817(4), 2Vcalc. = 46°; pleochroism is very weak; X pale greenish yellow, Y greenish blue, Z greenish blue; absorption X < Y = Z; orientation is uncertain. Chemical analysis by electron microprobe gave CuO 52.04, ZnO 0.78, BaO 0.11, As2O537.67, P2O50.32, SiO20.24, H2O 8.84, total 100.00 wt.%, with H2O calculated by difference. The empirical chemical formula is (Cu3.94, Zn0.06)Σ4.00H0.91(As1.97, P0.03, Si0.02)Σ2.02O8(OH)3.00˙H2O based on 12 oxygen atoms.Domerockite is triclinic, space group P, with a = 5.378(11), b = 8.962(18) c = 9.841(2) Å, α = 75.25(3), β = 83.56(3), γ = 79.97(3)°, V = 450.5(16) Å3 and Z = 2. The eight strongest lines in the X-ray powder diffraction pattern are [d (Å), (I)(hkl)]: 4.716 (30)(101, 002, 111), 3.697 (25)(121), 3.605 (30)(120, 12), 3.119 (60)(12), 3.073 (100)(1), 2.856 (40)(02, 030), 2.464 (50)(212, 13), 2.443 (40)(014). The crystal structure of domerockite has been solved by direct methods and refined to an R index of 7.44% using 2635 observed reflections. The structure comprises [Cuφ4] (φ = O, OH) chains of edge-sharing sharing, distorted octahedra that extend along [10] and are decorated by AsO4 tetrahedra to form sheets in the (010) plane. Dimers of edge-sharing [CuO4(OH)(H2O)] octahedra share corners with dimers of edge-sharing [CuO4(OH)] square pyramids to form zigzag chains which extend along [101]. The chains lie between and link to the sheets by sharings corners of octahedra, square pyramids and tetrahedra to form a heteropolyhedral framework.

Sveinbergeite, Ca(Fe2+6 Fe3+)Ti2(Si4O12)2O2(OH)5(H2O)4, a new astrophyllite-group mineral from the Larvik Plutonic Complex, Oslo Region, Norway: description and crystal structure

2011 ◽  
Vol 75 (5) ◽  
pp. 2687-2702 ◽  
Author(s):  
A. P. Khomyakov ◽  
F. Cámara ◽  
E. Sokolova ◽  
Y. Abdu ◽  
F. C. Hawthorne
Keyword(s):  
Crystal Structure ◽  
Manganese Oxides ◽  
Structure Refinement ◽  
Direct Methods ◽  
Calculated Density ◽  
Group Mineral ◽  
Amateur Mineralogist ◽  
Perfect Cleavage ◽  
Mohs Hardness ◽  
Deep Green

AbstractSveinbergeite, Ca(Fe2+6Fe3+)Ti2(Si4O12)2O2(OH)5(H2O)4, is a new astrophyllite-group mineral discovered in a syenite pegmatite at Buer on the Vesteroya peninsula, Sandefjord, Oslo Region, Norway. The mineral occurs in pegmatite cavities as 0.01—0.05 mm thick lamellar (0.2—0.5×5—10 mm) crystals forming rosette-like divergent groups and spherical aggregates, which are covered by brown coatings of iron (and possibly manganese) oxides, associated with magnesiokatophorite, aegirine, microcline, albite. calcite, fluorapatite, molybdenite, galena and a hochelagaite-like mineral. Crystals of sveinbergeite are deep green with a pale green streak and a vitreous and pearly lustre. Sveinbergeite has perfect cleavage on ﹛001﹜ and a Mohs hardness of 3. Its calculated density is 3.152 g/cm3. It is biaxial positive with α 1.745(2), β 1.746(2), γ 1.753(2), 2V(meas.) = 20(3)°. The mineral is pleochroic according to the scheme Z > X ∽ Y : Z is deep green, X and Y are brownish green. Orientation is as follows: X ┴ L (001), Y ᶺ b = 12°, Z = a, elongation positive. Sveinbergeite is triclinic, space group P1̄, a = 5.329(4), b = 11.803(8), c = 11.822(8) Å; α = 101.140(8)°, β = 98.224(8)°, γ = 102.442(8)°; V = 699.0(8) Å3; Z = 1. The nine strongest lines in the X-ray powder diffraction pattern [d in Å(I)(hkl)] are: 11.395(100)(001,010). 2.880(38)(004), 2.640(31)(2̄10,l̄41), 1.643(24)(07̄1,072), 2.492(20)(2l̄l), 1.616(15)(070), 1.573(14)(3̄2̄2), 2.270(13)(1̄3̄4) and 2.757(12)(1̄40,1̄3̄2). Chemical analysis by electron microprobe gave Nb2O5 0.55, TiO2 10.76, ZrO2 0.48, SiO2 34.41, A12O3 0.34, Fe2O3 5.57, FeO 29.39, MnO 1.27, CaO 3.87, MgO 0.52, K2O 0.49, Na2O 0.27, F 0.24, H2O 8.05, O=F -0.10, sum 96.11 wt.%, the amount of H2O was determined from structure refinement, and the valence state of Fe was calculated from structure refinement in accord with Mossbauer spectroscopy. The empirical formula, calculated on the basis of eight (Si + Al) p.f.u., is (Ca0.95Na0.12K0.14)Σ1.21(Fe2+5.65Fe3+0.93Mn0.25Mg0.18)Σ7.01(Ti1.86Nb0.06Zr0.05Fe3+)Σ2 (Si7091Al0.09)Σ8O34.61H12.34F0.17, Z = 1. The infrared spectrum of the mineral contains the following absorption frequencies: 3588, ∽3398 (broad), ∽3204 (broad), 1628, 1069, 1009, 942, 702, 655 and 560 cm–1. The crystal structure of the mineral was solved by direct methods and refined to an R1 index of 21.81%. The main structural unit in the sveinbergeite structure is an HOH layer which is topologically identical to that in the astrophyllite structure. Sveinbergeite differs from all other minerals of the astrophyllite group in the composition and topology of the interstitial A and B sites and linkage of adjacent HOH layers. The mineral is named in honour of Svein Arne Berge (b. 1949), a noted Norwegian amateur mineralogist and collector who was the first to observe and record this mineral from its type locality as a potential new species.

scholarly journals Fluoro-aluminoleakeite, NaNa2(Mg2Al2Li)Si8O22F2, a new mineral of the amphibole group from Norra Kärr, Sweden: description and crystal structure

2009 ◽  
Vol 73 (5) ◽  
pp. 817-824 ◽  
Author(s):  
R. Oberti ◽  
F. Cámaraite ◽  
F. C. Hawthorne ◽  
N. A. Ball
Keyword(s):  
Crystal Structure ◽  
Structure Refinement ◽  
Polarized Light ◽  
Crystal Structure Analysis ◽  
New Mineral ◽  
Monoclinic Space Group ◽  
Calculated Density ◽  
Greenish Blue ◽  
Dark Green ◽  
Pale Green

AbstractFluoro-aluminoleakeite, ideally , is a new mineral of the amphibole group from Norra Kärr, Sweden (IMA-CNMMNC 2009-012). It occurs in a proterozoic alkaline intrusion that mainly comprises a fine-grained schistose agpaitic nepheline-syenite (grennaite). Fluoro- aluminoleakeite occurs as isolated prismatic crystals 0.10–2 mm long in a syenitic matrix. Crystals are light greenish-blue with a greenish-blue streak. It is brittle, has a Mohs hardness of 6 and a splintery fracture; it is non-fluorescent with perfect {110} cleavage, no observable parting, and has a calculated density of 3.14 g cm–3. In plane-polarized light, it is pleochroic, X = pale green, Y = dark green, Z = pale green; X ^ a = 62.9° (in β obtuse), Y || b. Fluoro-aluminoleakeite is biaxial negative, α = 1.632(1), β = 1.638(1), γ = 1.643(1); 2Vobs. = 98.0(4)°, 2Vcalc. = 95.5°.MFluoro-aluminoleakeite is monoclinic, space group C2/m, a = 9.7043(5) Å, b = 17.7341(8) Å, c = 5.2833(3) Å, β = 104.067(4)°, V = 882.0(2) Å3, Z = 2. The eight strongest X-ray diffraction lines in the powder-diffraction pattern are [d in Å, (I), (hkl)]: 2.687, (100), (31, 151); 4.435, (80), (021, 040); 3.377, (80), (131); 2.527, (60), (02); 8.342, (50), (110); 3.096, (40), (310); 2.259, (40), (71, 12) and 2.557, (30), (002, 061). Analysis, by a combination of electron microprobe and crystal-structure refinement, gives SiO2 58.61, Al2O3 7.06, TiO2 0.32, FeO 3.27, Fe2O3 6.05, MgO 8.61, MnO 0.73, ZnO 0.43, CaO 0.05, Na2O 9.90, K2O 2.43, Li2O 1.62, F 3.37, H2Ocalc. 0.50, sum 101.08 wt.%. The formula unit, calculated on the basis of 24 (O,OH,F,Cl) p.f.u. with (OH) + F = 2 a.p.f.u., is A(Na0.65 O22W(F1.47OH0.53)Σ=2.00. Crystal-structure analysis shows CLi to be completely ordered at the M(3) site, and provided reliable site populations. Fluoro-aluminoleakeite is related to the end-member leakeite, , by the substitutions CFe3+ → CAl and WF → W(OH).

Fluoro-sodic-ferropedrizite, NaLi2(Fe22+Al2Li)Si8O22F2, a new mineral of the amphibole group from the Sutlug River, Tuva Republic, Russia: description and crystal structure

2009 ◽  
Vol 73 (3) ◽  
pp. 487-494 ◽  
Author(s):  
R. Oberti ◽  
M. Boiocchi ◽  
N. A. Ball ◽  
F. C. Hawthorne
Keyword(s):  
Crystal Structure ◽  
Country Rock ◽  
Structure Refinement ◽  
Polarized Light ◽  
New Mineral ◽  
Monoclinic Space Group ◽  
Crystal Structure Refinement ◽  
Calculated Density ◽  
Plagioclase Feldspar ◽  
Mohs Hardness

AbstractFluoro-sodic-ferropedrizite, ideally ANaBLi2C()TSi8O22WF2, is a new mineral of the amphibole group from the Sutlug River, Tuva Republic, Russia. It occurs at the endogenic contact of a Li-pegmatite with country rocks near to a diabase dyke and formed by reaction of the pegmatitic melt with the country rock. Fluoro-sodic-ferropedrizite occurs as prismatic to acicular crystals, ranging in length from 0.1–3 cm and widths of up to 50 μm. Crystals occur inparallel to sub-parallel aggregates up to 5 mm across ina matrix of calcite and plagioclase feldspar. Crystals are pale bluish-grey with a greyish-white streak.Fluoro-sodic-ferropedrizite is brittle, has a Mohs hardness of ~6 and a splintery fracture; it is non-fluorescent with perfect {110} cleavage, no observable parting, and has a calculated density of 3.116 g cm–3. In plane-polarized light, it is pleochroic, X = pale purple-grey, Y = light grey, Z = colourless; X ^ a = 71.2º (in β acute), Y || b, Z ^ c = 83.4º (in β obtuse). Fluoro-sodic-ferropedrizite is biaxial positive, α = 1.642(1), β = 1.644(1), γ = 1.652(1); 2V(obs) = 68.0(3)º, 2V(calc) = 56.4º. Fluoro-sodic-ferropedrizite is monoclinic, space group C2/m, a = 9.3720(4) Å, b = 17.6312(8) Å, c = 5.2732(3) Å, β = 102.247(4)º, V = 851.5(2) Å3, Z = 2. The strongest ten X-ray diffraction lines in the powder patternare (d in Å ,(I),(hkl)): 8.146,(10),(110); 2.686,(9),(151); 3.008,(8),(310); 4.430,(7),(021); 2.485,(6),(02); 3.383,(4),(131); 2.876,(3),(51, 11); 2.199,(3),(12); 4.030,(2),(111) and 3.795,(2),(31). Analysis by a combination of electron microprobe and crystal-structure refinement gives SiO2 59.81, Al2O3 12.66, TiO2 0.09, FeO 10.32, MgO 5.56, MnO 0.73, ZnO 0.17, CaO 0.20, Na2O 2.81, Li2O 4.80, F 2.43, H2Ocalc 1.10, sum = 99.65 wt.%. The formula unit, calculated on the basis of 24(O,OH,F) is A(Na0.68)B(Li1.92Na0.05Ca0.03)C() T(Si7.98Al0.02)O22W(F1.03OH0.97). Crystal-structure refinement shows Li to be completely ordered at the M(3) and M(4) sites. Fluoro-sodic-ferropedrizite, ideally ANaBLi2C()TSi8O22WF2, is related to the theoretical end-member ‘sodic-pedrizite’, ANaBLi2C(Mg2Al2Li)TSi8O22W(OH)2, by the substitutions CFe2+ → CMg and WF → W(OH).

Hydroniumpharmacosiderite, a new member of the pharmacosiderite supergroup from Cornwall, UK: structure and description

2010 ◽  
Vol 74 (5) ◽  
pp. 863-869 ◽  
Author(s):  
S. J. Mills ◽  
A. R. Kampf ◽  
P. A. Williams ◽  
P. Leverett ◽  
G. Poirier ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Diffraction Pattern ◽  
Powder Diffraction ◽  
Empirical Formula ◽  
Direct Methods ◽  
Structure Type ◽  
New Mineral ◽  
Calculated Density ◽  
X Ray ◽  
Mohs Hardness

AbstractHydroniumpharmacosiderite, ideally (H3O)Fe4(AsO4)3(OH)4·4H2O, is a new mineral from Cornwall, UK, probably from the St. Day group of mines. It occurs as a single yellowish green, slightly elongated cube, measuring 0.17 mm ×0.14 mm ×0.14 mm. The mineral is transparent with a vitreous lustre. It is brittle with a cleavage on {001}, has an irregular fracture, a white streak and a Mohs hardness of 2–3 (determined on H3O-exchanged pharmacosiderite). Hydroniumpharmacosiderite has a calculated density of 2.559 g cm–3 for the empirical formula. The empirical formula, based upon 20.5 oxygen atoms, is: [(H3O)0.50K0.48Na0.06]1.04(Fe3.79Al0.22)4.01[(As2.73P0.15)2.88O12](OH)4·4H2.14O. The five strongest lines in the X-ray powder diffraction pattern are [dobs(Å),Iobs,(hkl)]: 8.050,100,(001); 3.265,35,(112); 2.412,30,(113); 2.830,23,(202); 4.628,22,(111). Hydroniumpharmacosiderite is cubic, space group with a = 7.9587(2) Å, V = 504.11(2) Å3 and Z = 1. The crystal structure was solved by direct methods and refined to R1 = 0.0481 for 520 reflections with I > 2σ(I). The structure is consistent with determinations for H3O-exhchanged pharmacosiderite and the general pharmacosiderite structure type.

scholarly journals Luxembourgite, AgCuPbBi<sub>4</sub>Se<sub>8</sub>, a new mineral species from Bivels, Grand Duchy of Luxembourg

2020 ◽  
Vol 32 (4) ◽  
pp. 449-455
Author(s):  
Simon Philippo ◽  
Frédéric Hatert ◽  
Yannick Bruni ◽  
Pietro Vignola ◽  
Jiří Sejkora
Keyword(s):  
Crystal Structure ◽  
Structure Refinement ◽  
New Mineral ◽  
Tetrahedral Position ◽  
Calculated Density ◽  
Octahedral Sites ◽  
New Mineral Species ◽  
Distorted Octahedral ◽  
Mohs Hardness ◽  
Grand Duchy

Abstract. Luxembourgite, ideally AgCuPbBi4Se8, is a new selenide discovered at Bivels, Grand Duchy of Luxembourg. The mineral forms tiny fibres reaching 200 µm in length and 5 µm in diameter, which are deposited on dolomite crystals. Luxembourgite is grey, with a metallic lustre and without cleavage planes; its Mohs hardness is 3 and its calculated density is 8.00 g cm−3. Electron-microprobe analyses indicate an empirical formula Ag1.00(Cu0.82Ag0.20Fe0.01)Σ1.03Pb1.13Bi4.11(Se7.72S0.01)Σ7.73, calculated on the basis of 15 atoms per formula unit. A single-crystal structure refinement was performed to R1=0.0476, in the P21∕m space group, with a=13.002(1), b=4.1543(3), c=15.312(2) Å, β=108.92(1)∘, V=782.4(2) Å3, Z=2. The crystal structure is similar to that of litochlebite and watkinsonite and can be described as an alternation of two types of anionic layers: a pseudotetragonal layer four atoms thick and a pseudohexagonal layer that is one atom thick. In the pseudotetragonal layers the Bi1, Bi2 ,Bi3, Pb, and Ag1 atoms are localised, while the Cu2 and Bi4 atoms occur between the pseudotetragonal and the pseudohexagonal layers. Bi1, Bi2, and Bi3 atoms occur in weakly distorted octahedral sites, whereas Bi4 occurs in a distorted 7-coordinated site. Ag1 occupies a fairly regular octahedral site, Cu2 a tetrahedral position, and Pb occurs on a very distorted 8-coordinated site.

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.

Joanneumite, Cu(C3N3O3H2)2(NH3)2, a new mineral from Pabellón de Pica, Chile and the crystal structure of its synthetic analogue

2017 ◽  
Vol 81 (1) ◽  
pp. 155-166 ◽  
Author(s):  
Hans-Peter Bojar ◽  
Franz Walter ◽  
Judith Baumgartner
Keyword(s):  
Crystal Structure ◽  
Single Crystal ◽  
Structure Refinement ◽  
Structural Formula ◽  
New Mineral ◽  
Synthetic Analogue ◽  
X Ray Diffraction ◽  
Calculated Density ◽  
Cell Parameters ◽  
Mohs Hardness

AbstractThe new mineral joanneumite was found at Pabellón de Pica Mountain, Iquique Province, Tarapacá Region, Chile, where it occurs as violet microcrystalline aggregates up to 2 mm in size in small cracks in a gabbroic rock, which is covered by a guano deposit. Associated minerals are salammoniac, dittmarite, möhnite and gypsum. Joanneumite is non-fluorescent and the Mohs hardness is 1. The calculated density is 2.020 g cm–3. The infrared spectrum of joanneumite shows the frequencies of NH3 and isocyanurate groups and the absence of absorptions of H2O molecules and OH– ions. The chemical composition (electron microprobe data, the hydrogen was calculated from the structural formula, wt.%) is C 20.33, N 31.11, O 28.34, Cu 17.27, Zn 0.24, H 2.82, total 100.11. The empirical formula is Cu0.96Zn0.01N7.84C5.98O6.25H9.96 and the idealized formula is CuN8C6O6H10 with the structural formula Cu(C3N3O3H2)2(NH3)2. Due to the lack of suitable single crystals the synthetic analogue of joanneumite was prepared for the single-crystal structure refinement. The crystal structure was solved and refined to R = 0.025 based upon 1166 unique reflections with I > 2σ (I). Joanneumite is triclinic, space group P1̄, a = 4.982(1), b = 6.896(1), c = 9.115(2) Å, α = 90.53(3), β = 97.85(3), γ = 110.08(3)°, V = 290.8(1) Å3, Z = 1 obtained from single-crystal data at 100 K, which are in good agreement with cell parameters from powder diffraction data of joanneumite at 293 K: a = 5.042(1), b = 6.997(1), c = 9.099(2) Å, α = 90.05(3), β = 98.11(2), γ = 110.95(3)° and V = 296.3(1) Å3. The eight strongest lines of the powder X-ray diffraction pattern are [d, Å (I,%) (hkl)] 6.52 (68) (010), 5.15 (47) (011), 4.66 (21) (100, 110), 4.35 (9) (1̄11), 3.29 (6) (1̄20), 3.22 (7) (1̄1̄1), 3.140 (100) (1̄21), 2.074 (7) (1̄32). The crystal structure of joanneumite is identical with the structure of synthetic bis(isocyanurato) diamminecopper(II).

Wiklundite, ideally Pb2[4](Mn2+,Zn)3(Fe3+,Mn2+)2(Mn2+,Mg)19(As3+O3)2[(Si,As5+)O4]6(OH)18Cl6, a new mineral from Långban, Filipstad, Värmland, Sweden: Description and crystal structure

2017 ◽  
Vol 81 (4) ◽  
pp. 841-855 ◽  
Author(s):  
Mark A. Cooper ◽  
Frank C. Hawthorne ◽  
Jörgen Langhof ◽  
Ulf Hålenius ◽  
Dan Holtstam
Keyword(s):  
Crystal Structure ◽  
Structure Refinement ◽  
Direct Methods ◽  
New Mineral ◽  
Silicate Mineral ◽  
Calculated Density ◽  
International Mineralogical Association ◽  
Perfect Cleavage

AbstractWiklundite, ideally Pb2[4](Mn2+,Zn)3(Fe3+,Mn2+)2(Mn2+,Mg)19(As3+O3)2[(Si,As5+)O4]6(OH)18Cl6, isa new arseno-silicate mineral from Långban, Filipstad, Värmland, Sweden. Both the mineral and the name have been approved by the Commission on New Minerals, Nomenclature and Classification of the International Mineralogical Association (IMA 2015-057). Wiklundite and a disordered wiklundite-like mineral form radiating, sheaf-like aggregates (up to 1 mm long) of thin brownish-red and slightly bent lath-shaped crystals. It occurs in a dolomite-rich skarn in association with tephroite, mimetite, turneaurite, johnbaumite, jacobsite, barite, native lead, filipstadite andparwelite. Wiklundite is reddish brown to dark brown, and the streak is pale yellowish brown. The lustre is resinous to sub-metallic, almost somewhat bronzy, and wiklundite does not fluoresce under ultraviolet light. The calculated density is 4.072 g cm–3. Wiklundite is brittle with an irregular fracture, and has perfect cleavage on {001}; no parting or twinning was observed. Wiklundite is uniaxial (–), orange red and non-pleochroic in transmitted light, but shows incomplete extinction and distorted interference figures, preventing complete determination of optical properties. Electron-microprobe analysis (H2O calculated from the structure) of wiklundite gave SiO2 11.17, Al2O3 0.06, Fe2O3 4.46, As2O5 0.75, As2O3 6.81, MnO 47.89, ZnO 0.78,CaO 0.09, PbO 14.48, Cl 6.65, H2O 5.18, O=Cl2 –1.50, total 97.11 wt.%, As valences and H2O content taken from the crystal-structure refinement, and Fe3+/(Fe2+ + Fe3+) determined by Mössbauer spectroscopy. Wiklundite is hexagonal-rhombohedral, space group R3c, a = 8.257(2), c = 126.59(4) Å, V = 7474(6) Å3, Z = 6. The crystal structure of wiklundite was solved by direct methods and refined to a final R1 index of 3.2%. The structure consists of a stacking of five layers of polyhedra: three layers consist of trimers of edge-sharing Mn2+-dominant octahedra linked by (SiO4) tetrahedra, (Fe3+(OH)6) dominant octahedra and (AsO3) triangular pyramids; one layerof corner-sharing (SiO4) and (Mn2+O4) tetrahedra; and one layer of (Mn2+Cl6) octahedra and (Pb2+(OH)3Cl6) polyhedra. The mineral is named after Markus Wiklund (b. 1969) and Stefan Wiklund (b. 1972), the well-known Swedish mineral collectors who jointly found the specimen containing the mineral.

Kitagohaite, Pt7Cu, a new mineral from the Lubero region, North Kivu, Democratic Republic of the Congo

2014 ◽  
Vol 78 (3) ◽  
pp. 739-745 ◽  
Author(s):  
A. R. Cabral ◽  
R. Skála ◽  
A. Vymazalová ◽  
A. Kallistová ◽  
B. Lehmann ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Vickers Hardness ◽  
Democratic Republic ◽  
Mean Value ◽  
New Mineral ◽  
Calculated Density ◽  
Reflected Light ◽  
Republic Of The Congo ◽  
Mohs Hardness ◽  
North Kivu

AbstractKitagohaite, ideally Pt7Cu, is a new mineral from the Lubero region of North Kivu, Democratic Republic of the Congo. The mineral occurs as alluvial grains that were recovered together with other Pt-rich intermetallic compounds and Au. Kitagohaite is opaque, greyish white and malleable and has a metallic lustre and a grey streak. In reflected light, kitagohaite is white and isotropic. The crystal structure of kitagohaite is cubic, space group Fmm, of the Ca7Ge type, with a = 7.7891(3) Å, V = 472.57(5) Å3 and Z = 4. The strongest diffraction lines [d in Å(I)(hkl)] are: 2.246 (100)(222), 1.948(8)(004), 1.377 (77)(044), 1.174(27)(622), 1.123 (31)(444) and 0.893 (13)(662). The Vickers hardness is 217 kg mm−2 (VHN100), which is equivalent to a Mohs hardness of 3½ and the calculated density is 19.958(2) g cm−3. Electron-microprobe analyses gave a mean value (n = 13) of 95.49 wt.% Pt and 4.78 wt.%Cu, which corresponds to Pt6.93Cu1.07 on the basis of eight atoms. The new mineral is named for the Kitagoha river, in the Lubero region.

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).

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