scholarly journals Lead-tellurium oxysalts from Otto Mountain near Baker, California, USA: XII. Andychristyite, PbCu2+Te6+O5(H2O), a new mineral with hcp stair-step layers

2016 ◽  
Vol 80 (6) ◽  
pp. 1055-1065 ◽  
Author(s):  
Anthony R. Kampf ◽  
Mark A. Cooper ◽  
Stuart J. Mills ◽  
Robert M. Housley ◽  
George R. Rossman
Keyword(s):  
Empirical Formula ◽  
New Mineral ◽  
X Ray Diffraction ◽  
Calculated Density ◽  
Quartz Veins ◽  
Bluish Green ◽  
Cell Dimensions ◽  
Perfect Cleavage ◽  
Mohs Hardness ◽  
Unit Cell Dimensions

AbstractAndychristyite, PbCu2+Te6+O5(H2O), is a new tellurate mineral from Otto Mountain near Baker, California, USA. It occurs in vugs in quartz in association with timroseite. It is interpreted as having formed from the partial oxidation of primary sulfides and tellurides during or following brecciation of quartz veins. Andychristyite is triclinic, space group P1̄, with unit-cell dimensions a = 5.322(3), b = 7.098(4), c = 7.511 (4) Å, α = 83.486(7), β = 76.279(5), γ = 70.742(5)°, V = 260.0(2) Å3 and Z = 2. It forms as small tabular crystals up to ∼50 μm across, in sub-parallel aggregates. The colour is bluish green and the streak is very pale bluish green. Crystals are transparent with adamantine lustre. The Mohs hardness is estimated at between 2 and 3. Andychristyite is brittle with an irregular fracture and one perfect cleavage on {001}. The calculated density based on the empirical formula is 6.304 g/cm3. The mineral is optically biaxial, with large 2V, strong dispersion, and moderate very pale blue-green to medium blue-green pleochroism. The electron microprobe analyses (average of five) provided: PbO 43.21, CuO 15.38, TeO3 35.29, H2O 3.49 (structure), total 97.37 wt.%. The empirical formula (based on 6 O apfu) is: Pb0.98Cu2+0.98Te6+1.02O6H 1.96. The Raman spectrum exhibits prominent features consistent with the mineral being a tellurate, as well as an OH stretching feature confirming a hydrous component. The eight strongest powder X-ray diffraction lines are [dobs in Å(I)(hkl)]: 6.71(16)(010), 4.76(17)(110), 3.274(100)(120,102,012), 2.641(27)(102, 211, 112), 2.434(23)(multiple), 1.6736(17)(multiple), 1.5882(21)(multiple) and 1.5133(15)(multiple). The crystal structure of andychristyite (R1 = 0.0165 for 1511 reflections with Fo > 4σF) consists of stair-step-like hcp polyhedral layers of Te6+O6 and Cu2+O6 octahedra parallel to {001}, which are linked in the [001] direction by bonds to interlayer Pb atoms. The structures of eckhardite, bairdite, timroseite and paratimroseite also contain stair-step-like hcp polyhedral layers.

Leverettite from the Torrecillas mine, Iquique Provence, Chile: the Co-analogue of herbertsmithite

2013 ◽  
Vol 77 (7) ◽  
pp. 3047-3054 ◽  
Author(s):  
A. R. Kampf ◽  
M. J. Sciberras ◽  
P. A. Williams ◽  
M. Dini ◽  
A. A. Molina Donoso
Keyword(s):  
Empirical Formula ◽  
New Mineral ◽  
Calculated Density ◽  
Cell Parameters ◽  
Conchoidal Fracture ◽  
Bluish Green ◽  
Perfect Cleavage ◽  
Mohs Hardness ◽  
Deep Green ◽  
Light Green

AbstractThe new mineral leverettite (IMA 2013-011), ideally Cu3CoCl2(OH)6, was found at the Torrecillas mine, Salar Grande, Iquique Province, Chile, where it occurs as a supergene alteration phase in association with akaganéite, anhydrite, chalcophanite, goethite, halite, manganite, pyrite, quartz and todorokite. Crystals of leverettite are steep rhombohedra to 1 mm with {101} prominent and modified by {001}, sometimes forming V-shaped twins by reflection on {10}. The crystals can also form finger-like, parallel stacked growths along the c axis. The new mineral is medium to deep green in colour and has a light green streak. Crystals are transparent with a vitreous lustre. Mohs hardness is ∼3 and the crystals have a brittle tenacity, a perfect cleavage on {101} and a conchoidal fracture. The measured density is 3.64(2) g cm–3 and calculated density based on the empirical formula is 3.709 g cm–3. Optically, leverettite is uniaxial (–) with ω and ε > 1.8 and exhibits pleochroism with O (bluish green) > E (slightly yellowish green). The empirical formula, determined from electron-microprobe analyses is Cu3(Co0.43Cu0.40Mn0.17Ni0.07Mg0.01)Σ1.08Cl1.87O6.13H6. Leverettite is trigonal (hexagonal), space group Rm, unit-cell parameters a = 6.8436(6) and c = 14.064(1) Å, V = 570.42(8) Å3, Z = 3. The eight strongest X-ray powder diffraction lines are [dobs Å (I)(hkl)]: 5.469(90)(101), 4.701(18)(003), 2.905(22)(021), 2.766(100)(113), 2.269(66)(024), 1.822(26)(033), 1.711(33)(220), 1.383(23)(128). The structure, refined to R1 = 0.023 for 183 Fo > 4σF reflections, shows leverettite to be isostructural with herbertsmithite and gillardite.

scholarly journals Fluorarrojadite-(BaNa), BaNa4CaFe13Al(PO4)11(PO3OH)F2, a new member of the arrojadite group from Gemerská Poloma, Slovakia

2018 ◽  
Vol 82 (4) ◽  
pp. 863-876 ◽  
Author(s):  
Martin Števko ◽  
Jiří Sejkora ◽  
Pavel Uher ◽  
Fernando Cámara ◽  
Radek Škoda ◽  
...  
Keyword(s):  
Empirical Formula ◽  
New Mineral ◽  
Monoclinic Space Group ◽  
X Ray Diffraction ◽  
Calculated Density ◽  
Yellow Colour ◽  
Fine Grained ◽  
Quartz Veins ◽  
Mohs Hardness ◽  
Dominant Cation

ABSTRACTThe new mineral fluorarrojadite-(BaNa), ideally BaNa4CaFe13Al(PO4)11(PO3OH)F2 was found on the dump of Elisabeth adit near Gemerská Poloma, Slovakia. It occurs in hydrothermal quartz veins intersecting highly fractionated, topaz–zinnwaldite S-type leucogranite. Fluorarrojadite-(BaNa) is associated with fluorapatite, ‘fluordickinsonite-(BaNa)’, triplite, viitaniemiite and minor amounts of other minerals. It forms fine-grained irregular aggregates up to 4 cm x 2 cm, which consist of individual anhedral grains up to 0.01 mm in size. It has a yellowish-brown to greenish-yellow colour, very pale yellow streak and a vitreous to greasy lustre. Mohs hardness is ~4½ to 5. The fracture is irregular and the tenacity is brittle. The measured density is 3.61(2) g cm–3 and calculated density is 3.650 g cm–3. Fluorarrojadite-(BaNa) is biaxial (+) and nonpleochroic. The calculated refractive index based on empirical formula is 1.674. The empirical formula (based on 47 O and 3 (OH + F) apfu) is A1(Ba0.65K0.35)Σ1.00 A2Na0.35 B1(Na0.54Fe0.46)Σ1.00 B2Na0.54Ca(Ca0.74Sr0.20Pb0.02Ba0.04)Σ1.00Na2 Na3Na0.46 M(Fe7.16Mn5.17Li0.37Mg0.12Sc0.08Zn0.06Ga0.02Ti0.02)Σ13.00 Al1.02P11O44PO3.46(OH)0.54 W(F1.54OH0.46). Fluorarrojadite-(BaNa) is monoclinic, space group Cc, a = 16.563(1) Å, b = 10.0476(6) Å, c = 24.669(1) Å, β = 105.452(4)°, V = 3957.5(4) Å3 and Z = 4. The seven strongest reflections in the powder X-ray diffraction pattern are [dobs in Å, (I), hkl]: 3.412, (21), 116; 3.224, (37), 206; 3.040, (100), 42$\bar 4$; 2.8499, (22), 33$\bar 3$; 2.7135, (56), 226; 2.5563, (33), 028 and 424; 2.5117, (23), 040. The new mineral is named according to the nomenclature scheme of arrojadite-group minerals, approved by the IMA CNMNC. In fluorarrojadite-(BaNa), Fe2+ is a dominant cation at the M site (so the root-name is arrojadite) and two suffixes are added to the root-name according to the dominant cation of the dominant valence state at the A1 (Ba2+) and B1 sites (Na+). A prefix fluor is added to the root-name as F– is dominant over (OH)– at the W site.

Pauladamsite, Cu4(SeO3)(SO4)(OH)4·2H2O, a new mineral from the Santa Rosa mine, Darwin district, California, USA

2016 ◽  
Vol 80 (6) ◽  
pp. 949-958 ◽  
Author(s):  
A. R. Kampf ◽  
S. J. Mills ◽  
B. P. Nash
Keyword(s):  
New Mineral ◽  
X Ray Diffraction ◽  
Secondary Oxidation ◽  
Calculated Density ◽  
Teller Distortion ◽  
Jahn Teller ◽  
Perfect Cleavage ◽  
Mohs Hardness ◽  
Jahn Teller Distortion ◽  
Pale Green

AbstractPauladamsite (IMA2015-005), Cu4(SeO3)(SO4)(OH)4·2H2O, is a new mineral from the Santa Rosa mine, Darwin district, Inyo County, California, USA, where it occurs as a secondary oxidation-zone mineral in association with brochantite, chalcanthite, gypsum, ktenasite, mimetite, schulenbergite and smithsonite on limonitic gossan. Pauladamsite forms green, multiply twinned blades up to 0.5 mm long grouped in radial sprays. The streak is pale green. Crystals are transparent and have vitreous to silky lustre. The Mohs hardness is ∼2, the tenacity is brittle, the fracture is irregular and crystals exhibit one perfect cleavage on [001]. The calculated density is 3.535 g/cm3. Electron microprobe analyses provided: CuO 48.96, ZnO 3.56, SeO2 18.82, SO3 13.90, H2O 13.29 (calc.), total 98.53 wt.%. The empirical formula (based on 13 O apfu) is: (Cu3.55Zn0.25)∑3.80Se0.98SO13H8.50. Pauladamsite is triclinic, P1, a = 6.0742(7), b = 8.4147(11), c = 10.7798 (15) Å, α = 103.665(7), β = 95.224(7), γ = 90.004(6)°, V = 533.03(12) Å3 and Z = 2. The eight strongest lines in the powder X-ray diffraction pattern are [dobs in Å(I)(hkl)]: 10.5(46)(011); 3.245(100)(001); 5.81(50)(011); 2.743(49)(112); 3.994(67)(012); 3.431(23)(1̄12,1̄2̄1,1̄20); 2.692(57)(03̄2,1̄22,2̄1̄2); and 2.485(39)(21̄2,1̄3̄2,02̄4). The structure of pauladamsite (R1 = 10.6% for 2086 Fo > 4σF) contains Cu2+O6 octahedra, SO4 tetrahedra and Se4+O3 pyramids. There are four different CuO6 octahedra, each of which exhibits typical Jahn-Teller distortion, with four short equatorial Cu–O bonds and two much longer apical Cu–O bonds. The CuO6 octahedra share edges to form five-octahedra-wide bands extending along [100]. Adjacent bands are connected in the [011̄] direction by bridging SO4 tetrahedra and in the [011] direction by bridging Se4+O3 pyramids, thereby forming a framework.

Crystal structure and crystal chemistry of fluoro-potassic-magnesio-arfvedsonite from Monte Metocha, Xixano region, Mozambique, and discussion of the holotype from Quebec, Canada

2010 ◽  
Vol 74 (6) ◽  
pp. 951-960 ◽  
Author(s):  
R. Oberti ◽  
M. Boiocchi ◽  
F. C. Hawthorne ◽  
P. Robinson
Keyword(s):  
Polarized Light ◽  
X Ray Diffraction ◽  
Calculated Density ◽  
Amphibole Composition ◽  
Fine Grained ◽  
Holotype Specimen ◽  
Cell Dimensions ◽  
Mohs Hardness ◽  
Crystallization Conditions ◽  
Unit Cell Dimensions

AbstractFluoro-potassic-magnesio-arfvedsonite, ideally AKBNa2c(Mg4Fe3+)TSi8O22wF2, has been found in a dyke ∼25 km southwest of Monte Metocha, Xixano region, northeastern Mozambique. Fluoro-potassic-magnesio-arfvedsonite and low sanidine form a fine-grained mafic, ultrapotassic, peralkaline igneous rock without visible phenocrysts. The amphibole is brittle, has a Mohs hardness of 6 and a splintery fracture; it is non-fluorescent with perfect {110} cleavage and no observable parting, and has a calculated density of 3.174 gcm−3. In plane-polarized light, it is pleochroic, X= pale grey-green, Y = blue-green, Z = pale grey; X ^ c = 23.6° (in β obtuse), Y ‖ b, Z ^ c = 66.4° (in β acute). Fluoro-potassic-magnesio-arfvedsonite is biaxial negative, α = 1.652(2), β = 1.658(2), γ = 1.660(2); 2Vobs = 22.5(7)°, 2Vcalc = 30.2°. The unit-cell dimensions are a = 9.9591(4), b = 17.9529(7), c = 5.2867(2) Å, β = 104.340(1)°, V = 919.73(10) Å3, Z = 2. The nine strongest X-ray diffraction lines in the experimental powder pattern are: [d in Å(I)(hkl)]: 2.716(100)(151), 3.410(70)(131), 8.475(50)(110), 3.178(50)(310), 3.309(30)(240), 2.762(20)(31), 2.549(20)(260), 2.351(10)(51), 2.269(10)(331). Electron microprobe analysis gave: SiO2 54.25, A12O3 0.03, TiO2 1.08, FeO 6.69, Fe2O3 8.07, MgO 13.99, MnO 0.32, ZnO 0.05, CaO 1.16, Na2O 6.33, K2O 5.20, F 2.20, H2Ocalc 0.74, sum 99.18 wt.%. The formula unit, calculated on the basis of 24 (O,OH,F) with (OH+F) = 2−(2 Ti), is AKa0.98B(Na1.18Ca0.18)∑1.99C(Mg3.07Fe0.832+Mn0.04Al0.01Fe0.903+Ti0.12Zn0.01)∑=4.98TSi8O22W[Fi.o3(OH)0.73O0.24]∑2.00 and confirms the usual pattern of cation order in the amphibole structure. The presence of a significant oxo component (locally balanced by Ti at the M(1) site) is related to the crystallization conditions. The presence of Fe3+ at the T sites, originally suggested for the holotype specimen, is discounted for this amphibole composition.

Bettertonite, [Al6(AsO4)3(OH)9(H2O)5]·11H2O, a new mineral from the Penberthy Croft mine, St. Hilary, Cornwall, UK, with a structure based on polyoxometalate clusters

2015 ◽  
Vol 79 (7) ◽  
pp. 1849-1858 ◽  
Author(s):  
I.E. Grey ◽  
A.R. Kampf ◽  
J.R. Price ◽  
C.M. Macrae
Keyword(s):  
Layer Structure ◽  
New Mineral ◽  
Water Molecules ◽  
Monoclinic Space Group ◽  
X Ray Diffraction ◽  
Calculated Density ◽  
Hexagonal Ring ◽  
Metal Atoms ◽  
Cell Dimensions ◽  
Unit Cell Dimensions

AbstractBettertonite, ideally [Al6(AsO4)3(OH)9(H2O)5]·11H2O, is a new mineral from the Penberthy Croft mine, St. Hilary, Cornwall, England, UK. It occurs as tufts of white, ultrathin (sub-micrometre) rectangular laths, with lateral dimensions generally <20 μm. The laths are flattened on {010} and exhibit the forms {010}, {100} and {001}. The mineral is associated closely with arsenopyrite, chamosite, liskeardite, pharmacoalumite, pharmacosiderite and quartz. Bettertonite is translucent with a white streak and a vitreous to pearly, somewhat silky lustre. The calculated density is 2.02 g/cm3. Optically, bettertonite is biaxial positive with α = 1.511(1), β = 1.517(1), γ = 1.523(1) (in white light). The optical orientation is X = c, Y= b, Z = a. Pleochroism was not observed. Electron microprobe analyses (average of 4) with H2O calculated on structural grounds and analyses normalized to 100% gave Al2O3 = 29.5, Fe2O3 = 2.0, As2O5= 30.1, SO3 = 1.8, Cl = 0.5, H2O = 36.2. The empirical formula, based on 9 metal atoms is Al5.86Fe0.26(AsO4)2.65(SO4)0.23(OH)9.82Cl0.13(H2O)15.5. Bettertoniteis monoclinic, space group P21/c with unit-cell dimensions (100 K): a = 7.773(2), b = 26.991(5), c = 15.867(3) Å, β = 94.22(3)°. The strongest lines in the powder X-ray diffraction pattern are [dobs in Å(I)(hkl)] 13.648(100)(011); 13.505(50) (020); 7.805(50)(031); 7.461(30)(110); 5.880(20)(130); 3.589(20)(02); 2.857(14)(182). The structure of bettertonite was solved and refined to R1 = 0.083 for 2164 observed (I > 2σ(I)) reflections to a resolutionof 1 Å. Bettertonite has a heteropolyhedral layer structure, with the layers parallel to (010). The layers are strongly undulating and their stacking produces large channels along [100] that are filled with water molecules. The basic building block in the layers is a hexagonal ring ofedge-shared octahedra with an AsO4 tetrahedron attached to one side of the ring by corner-sharing. These polyoxometalate clusters, of composition [AsAl6O11(OH)9(H2O)5]8–, are interconnected along [100] and [001]by corner-sharing with other AsO4 tetrahedra.

scholarly journals Joteite, Ca2CuAl[AsO4][AsO3(OH)]2(OH)2·5H2O, a new arsenate with a sheet structure and unconnected acid arsenate groups

2013 ◽  
Vol 77 (6) ◽  
pp. 2811-2823 ◽  
Author(s):  
A. R. Kampf ◽  
S. J. Mills ◽  
R. M. Housley ◽  
G. R. Rossman ◽  
B. P. Nash ◽  
...  
Keyword(s):  
Empirical Formula ◽  
New Mineral ◽  
Optical Orientation ◽  
Secondary Mineral ◽  
Calculated Density ◽  
X Ray ◽  
Cell Parameters ◽  
Perfect Cleavage ◽  
Mohs Hardness ◽  
Greenish Blue

AbstractJoteite (IMA2012-091), Ca2CuAl[AsO4][AsO3(OH)]2(OH)2·5H2O, is a new mineral from the Jote mine, Tierra Amarilla, Copiapó Province, Atacama, Chile. The mineral is a late-stage, low-temperature, secondary mineral occurring with conichalcite, mansfieldite, pharmacoalumite, pharmacosiderite and scorodite in narrow seams and vughs in the oxidized upper portion of a hydrothermal sulfide vein hosted by volcanoclastic rocks. Crystals occur as sky-blue to greenish-blue thin blades, flattened and twinned on {001}, up to ~300 μm in length, and exhibiting the forms {001}, {010}, {10}, {20} and {111}. The blades are commonly intergrown in wheat-sheaf-like bundles, less commonly in sprays, and sometimes aggregated as dense crusts and cavity linings. The mineral is transparent and has a very pale blue streak and vitreous lustre. The Mohs hardness is estimated at 2 to 3, the tenacity is brittle, and the fracture is curved. It has one perfect cleavage on {001}. The calculated density based on the empirical formula is 3.056 g/cm3. It is optically biaxial (–) with α = 1.634(1), β = 1.644(1), γ = 1.651(1) (white light), 2Vmeas = 78(2)° and 2Vcalc = 79.4°. The mineral exhibits weak dispersion, r < v. The optical orientation is X ≈ c*; Y ≈ b*. The pleochroism is Z (greenish blue) > Y (pale greenish blue) > X (colourless). The normalized electron-microprobe analyses (average of 5) provided: CaO 15.70, CuO 11.22, Al2O38.32, As2O546.62, H2O 18.14 (structure), total 100 wt.%. The empirical formula (based on 19 O a.p.f.u.) is: Ca1.98Cu1.00Al1.15As2.87H14.24O19. The mineral is slowly soluble in cold, concentrated HCl. Joteite is triclinic, P1, with the cell parameters: a = 6.0530(2), b = 10.2329(3), c = 12.9112(4) Å, α = 87.572(2), β = 78.480(2), γ = 78.697(2)°, V = 768.40(4) Å3 and Z = 2. The eight strongest lines in the X-ray powder diffraction pattern are [dobs Å (I)(hkl)]: 12.76(100)(001), 5.009(23)(020), 4.206(26)(120,003,121), 3.92(24)(022,02,02), 3.40(25)(1̄13), 3.233(19)(031,023,123,02̄3), 2.97(132,201) and 2.91(15)(22,13). In the structure of joteite (R1 = 7.72% for 6003 Fo > 4σF), AsO4 and AsO3 (OH) tetrahedra, AlO6 octahedra and Cu2+O5 square pyramids share corners to form sheets parallel to {001}. In addition, 7- and 8-coordinate Ca polyhedra link to the periphery of the sheets yielding thick slabs. Between the slabs are unconnected AsO3(OH) tetrahedra, which link the slabs only via hydrogen bonding. The Raman spectrum shows features consistent with OH and/or H2O in multiple structural environments. The region between the slabs may host excess Al in place of some As.

Alwilkinsite-(Y), a new rare-earth uranyl sulfate mineral from the Blue Lizard mine, San Juan County, Utah, USA

2017 ◽  
Vol 81 (4) ◽  
pp. 895-907 ◽  
Author(s):  
Anthony R. Kampf ◽  
Jakub Plášil ◽  
Jiří Čejka ◽  
Joe Marty ◽  
Radek Škoda ◽  
...  
Keyword(s):  
New Mineral ◽  
San Juan ◽  
X Ray Diffraction ◽  
Uranyl Sulfate ◽  
Calculated Density ◽  
Secondary Alteration ◽  
X Ray ◽  
Perfect Cleavage ◽  
Mohs Hardness ◽  
San Juan County

AbstractThe new mineral alwilkinsite-(Y) (IMA2015-097), Y(H2O)7[(UO2)3(SO4)2O(OH)3]·7H2O, was found in the Blue Lizard mine, San Juan County, Utah, USA, where it occurs as a secondary alteration phase.The mineral is slightly flexible before brittle failure with splintery fracture and perfect cleavage parallel to [010], has Mohs hardness of ∼2–2½, exhibits dull greenish-grey fluorescence and has a calculated density of 3.371 g cm–3. Alwilkinsite-(Y) occursas yellowish-green needles, elongate on [010], with domatic terminations and exhibits the forms {102}, {301} and {124}. It is optically biaxial (+) with α = 1.573(1), β = 1.581(1), γ = 1.601(1) (white light), the measured 2V is 65.3(1)°, the dispersion is r<v (weak), the optical orientation is X = c, Y = a, Z = b and there is no pleochroism. Electron microprobe analyses yielded the empirical formula (Y0.66Dy0.08Gd0.06Er0.05Nd0.03Yb0.03Sm0.02Ce0.01)∑0.94(H2O)7[(UO2)3(S1.01O4)2O(OH)3]·7H2O.The eight strongest powder X-ray diffraction lines are [dobs Å(I)(hkl)]: 9.88(100)(101,002), 7.47(13)(102), 5.621(17)(103,201), 4.483(18)(104), 3.886(14)(130,222), 3.322(46)(multiple), 3.223(13)(multiple) and 3.145(16)(034). Alwilkinsite-(Y) is orthorhombic,P212121, a = 11.6194(5), b = 12.4250(6), c = 19.4495(14) Å, V = 2807.9(3) Å3 and Z = 4. The structure of alwilkinsite-(Y) (R1 = 0.042 for 4244 Fo > 4σF)contains edge-sharing chains of uranyl bipyramids with outlying sulfate tetrahedra that are similar to the chain linkages within the uranyl sulfate sheets of the zippeite structure. Short segments of the uranyl sulfate chains in the alwilkinsite-(Y) structure have the same topology as portionsof the uranyl sulfate linkages in uranopilite. Alwilkinsite-(Y) is named for Alan (Al) J. Wilkins, MD (born 1955), the discoverer of the mineral.

Geschieberite, K2(UO2)(SO4)2(H2O)2, a new uranyl sulfate mineral from Jáchymov

2015 ◽  
Vol 79 (1) ◽  
pp. 205-216 ◽  
Author(s):  
J. Plášil ◽  
J. Hloušek ◽  
A. V. Kasatkin ◽  
R. Škoda ◽  
M. Novák ◽  
...  
Keyword(s):  
Pentagonal Bipyramid ◽  
New Mineral ◽  
X Ray Diffraction ◽  
Uranyl Sulfate ◽  
Calculated Density ◽  
Perfect Cleavage ◽  
Mohs Hardness ◽  
Bright Green ◽  
Stretching Vibrations ◽  
Crystalline Aggregates

AbstractThe new mineral geschieberite (IMA2014-006), K2(UO2)(SO4)2(H2O)2, was found in the Svornost mine, Jáchymov, Czech Republic, where it occurs as a secondary alteration phase after uraninite in association with adolfpateraite and gypsum. Geschieberite forms crystalline aggregates of bright green colour (when thick) composed of multiply intergrown prismatic crystals elongated on [001] typically reaching 0.1–0.2 mm across; observable forms are {010} and {001}. Crystals are translucent to transparent with a vitreous lustre. The mineral is brittle, with perfect cleavage on {100} and an uneven fracture. It has a greenish-white streak and a probable Mohs hardness of ∼2. The mineral is slightly soluble in cold H2O. The calculated density is 3.259 g cm–3. The mineral exhibits strong yellowish-green fluorescence under both shortwave and longwave UV radiation. Optically, geschieberite is biaxial (–), with β = 1.596(2) and γ = 1.634(4) (measured at 590 nm), with X = a. Electron-microprobe analyses provided Na2O 0.23, K2O 14.29, MgO 2.05, CaO 0.06, UO3 49.51, SO3 27.74, H2O 6.36 (structure), total 100.24 wt.%, yielding the empirical formula (K1.72Mg0.29Na0.04Ca0.01)Σ2.06(U0.98O2)(S0.98O4)2(H2O)2 based on 12 O atoms per formula unit. The Raman spectrum is dominated by the symmetric stretching vibrations of UO22+, SO42– and weaker O–H stretching vibrations. Geschieberite is orthorhombic, Pna21, with a = 13.7778(3), b = 7.2709(4), c = 11.5488(2) Å, V = 1156.92(7) Å3, Z = 4. The eight strongest powder X-ray diffraction lines are [dobs in Å (hkl) Irel]: 6.882 (200) 100, 5.622 (111) 53, 4.589 (211) 12, 4.428 (202) 16, 3.681 (311) 18, 3.403 (013) 12, 3.304 (401,1̄13) 15 and 3.006 (122) 17. The structure, refined to R = 0.028 for 1882 I > 3σ(I) reflections, contains [(UO2)(SO4)2(H2O)]2– sheets that are based on the protasite anion topology. Sheets are stacked perpendicular to a. Potassium atoms and one H2O molecule are located between these sheets, providing an interlayer linkage. The remaining H2O molecule is localized within the structural unit, at the free vertex of the uranyl pentagonal bipyramid; this vertex does not link to sulfate tetrahedra. The mineral is named for one of the most important ore veins in Jáchymov – the Geschieber vein.

scholarly journals Bluebellite and mojaveite, two new minerals from the central Mojave Desert, California, USA

2014 ◽  
Vol 78 (5) ◽  
pp. 1325-1340 ◽  
Author(s):  
S. J. Mills ◽  
A. R. Kampf ◽  
A. G. Christy ◽  
R. M. Housley ◽  
G. R. Rossman ◽  
...  
Keyword(s):  
Empirical Formula ◽  
Mojave Desert ◽  
Unit Cell ◽  
Unit Cell Parameters ◽  
Calculated Density ◽  
Cell Parameters ◽  
Bluish Green ◽  
Perfect Cleavage ◽  
Mohs Hardness ◽  
Greenish Blue

AbstractBluebellite, Cu6[I5+O3(OH)3](OH)7Cl and mojaveite, Cu6[Te6+O4(OH)2](OH)7Cl, are new secondary copper minerals from the Mojave Desert. The type locality for bluebellite is the D shaft, Blue Bell claims, near Baker, San Bernardino County, California, while cotype localities for mojaveite are the E pit at Blue Bell claims and also the Bird Nest drift, Otto Mountain, also near Baker. The two minerals are very similar in their properties. Bluebellite is associated particularly with murdochite, but also with calcite, fluorite, hemimorphite and rarely dioptase in a highly siliceous hornfels. It forms bright bluishgreen plates or flakes up to ~20 mm 620 mm 65 mm in size that are usually curved. The streak is pale bluish green and the lustre is adamantine, but often appears dull because of surface roughness. It is non-fluorescent. Bluebellite is very soft (Mohs hardness ~1), sectile, has perfect cleavage on {001} and an irregular fracture. The calculated density based on the empirical formula is 4.746 g cm–3. Bluebellite is uniaxial (–), with mean refractive index estimated as 1.96 from the Gladstone-Dale relationship. It is pleochroic O (bluish green) >> E (nearly colourless). Electron microprobe analyses gave the empirical formula Cu5.82I0.99Al0.02Si0.12O3.11(OH)9.80Cl1.09based on 14 (O+Cl) a.p.f.u. The Raman spectrum shows strong iodate-related bands at 680, 611 and 254 cm–1. Bluebellite is trigonal, space group R3, with the unit-cell parameters: a = 8.3017(5), c = 13.259(1) Å , V = 791.4(1) Å 3 and Z = 3. The eight strongest lines in the powder X-ray diffraction (XRD) pattern are [dobs/Å (I) (hkl)]: 4.427(99)(003), 2.664(35)(211), 2.516(100)(212̄ ), 2.213(9)(006), 2.103(29)(033,214), 1.899(47)(312,215̄ ), 1.566(48)(140,217) and 1.479(29)(045,143̄ ,324).Mojaveite occurs at the Blue Bell claims in direct association with cerussite, chlorargyrite, chrysocolla, hemimorphite, kettnerite, perite, quartz and wulfenite, while at the Bird Nest drift, it is associated with andradite, chrysocolla, cerussite, burckhardtite, galena, goethite, khinite, mcalpineite, thorneite, timroseite, paratimroseite, quartz and wulfenite. It has also been found at the Aga mine, Otto Mountain, with cerussite, chrysocolla, khinite, perite and quartz. Mojaveite occurs as irregular aggregates of greenish-blue plates flattened on {001} and often curved, which rarely show a hexagonal outline, and also occurs as compact balls, from sky blue to medium greenish blue in colour. Aggregates and balls are up to 0.5 mm in size. The streak of mojaveite is pale greenish blue, while the lustre may be adamantine, pearly or dull, and it is non-fluorescent. The Mohs hardness is ~1. It is sectile, with perfect cleavage on {001} and an irregular fracture. The calculated density is 4.886 g cm–3, based on the empirical formulae and unit-cell dimensions. Mojaveite is uniaxial (–), with mean refractive index estimated as 1.95 from the Gladstone-Dale relationship. It is pleochroic O (greenish blue) >> E (light greenish blue). The empirical formula for mojaveite, based on 14 (O+Cl) a.p.f.u., is Cu5.92Te1.00Pb0.08Bi0.01O4(OH)8.94Cl1.06. The most intense Raman bands occur at 694, 654 (poorly resolved), 624, 611 and 254 cm–1. Mojaveite is trigonal, space group R3, with the unit-cell parameters: a = 8.316(2), c = 13.202(6) Å and V = 790.7(1) Å 3. The eight strongest lines in the powder XRD pattern are [dobs/Å (I) (hkl)]: 4.403(91)(003), 2.672(28)(211), 2.512(100)(212̄ ), 2.110(27)(033,214), 1.889(34)(312,215̄ ,223̄ ), 1.570(39)(404,140,217), 1.481(34)(045,143̄ ,324) and 1.338(14)(422). Diffraction data could not be refined, but stoichiometries and unit-cell parameters imply that bluebellite and mojaveite are very similar in crystal structure. Structure models that satisfy bondvalence requirements are presented that are based on stackings of brucite-like Cu6MX14layers, where M = (I or Te) and X = (O, OH and Cl). Bluebellite and mojaveite provide a rare instance of isotypy between an iodate containing I5+with a stereoactive lone electron pair and a tellurate containing Te6+with no lone pair.

scholarly journals Kyawthuite, Bi3+Sb5+O4, a new gem mineral from Mogok, Burma (Myanmar)

2017 ◽  
Vol 81 (3) ◽  
pp. 477-484 ◽  
Author(s):  
Anthony R. Kampf ◽  
George R. Rossman ◽  
Chi Ma ◽  
Peter A. Williams
Keyword(s):  
Monoclinic Space Group ◽  
Optical Orientation ◽  
X Ray Diffraction ◽  
Calculated Density ◽  
Electron Pairs ◽  
X Ray ◽  
Conchoidal Fracture ◽  
Cell Dimensions ◽  
Mohs Hardness ◽  
Unit Cell Dimensions

AbstractKyawthuite, Bi3+Sb5+O4, is a new gem mineral found as a waterworn crystal in alluvium at Chaung-gyi-ah-le-ywa in the Chaung-gyi valley, near Mogok, Burma (Myanmar). Its description is based upon a single sample, which was faceted into a 1.61-carat gem.The composition suggests that the mineral formed in a pegmatite. Kyawthuite is monoclinic, space group I2/c, with unit cell dimensions a = 5.4624(4), b = 4.88519(17), c = 11.8520(8) Å, β = 101.195(7)°, V = 310.25(3) Å3and Z = 4. The colour is reddish orange and the streak is white. It is transparent with adamantine lustre. The Mohs hardness is 5½. Kyawthuite is brittle with a conchoidal fracture and three cleavages: {001} perfect, {110} and {110} good. The measured density is 8.256(5) g cm–3and the calculated density is 8.127 g cm–3. The mineral is optically biaxial with 2V = 90(2)°. The predicted indices of refraction are α = 2.194, β = 2.268, γ = 2.350. Pleochroism is imperceptible and the optical orientation is X = b; Y≈ c; Z ≈ a. Electron microprobe analyses, provided the empirical formula (Bi0.823+Sb0.183+)∑1.00(Sb0.995+Ta0.015+)∑1.00O4. The Raman spectrumis similar to that of synthetic Bi3+Sb5+O4. The infrared spectrum shows a trace amount of OH/H2O. The eight strongest powder X-ray diffraction lines are [dobs in Å(I)(hkl)]: 3.266(100)(112), 2.900(66)(112), 2.678(24)(200), 2.437(22)(020,114), 1.8663(21)(024), 1.8026(43)(116,220,204), 1.6264(23)(224,116) and 1.5288(28)(312,132). In the crystal structure of kyawthuite (R1 = 0.0269 for 593 reflections with Fo > 4σF), Sb5+O6 octahedrashare corners to form chequerboard-like sheets parallel to {001}. Atoms of Bi3+, located above and below the open squares in the sheets, form bonds to the O atoms in the sheets, thereby linking adjacent sheets into a framework. The Bi3+ atom is in lopsided 8 coordination,typical of a cation with stereoactive lone electron pairs. Kyawthuite is isostructural with synthetic β-Sb2O4 and clinocervantite (natural β-Sb2O4).

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