scholarly journals Aurihydrargyrumite, a Natural Au6Hg5 Phase from Japan

Minerals ◽  
2018 ◽  
Vol 8 (9) ◽  
pp. 415 ◽  
Author(s):  
Daisuke Nishio-Hamane ◽  
Takahiro Tanaka ◽  
Tetsuo Minakawa
Keyword(s):  
Empirical Formula ◽  
Thick Layer ◽  
Metallic Silver ◽  
New Mineral ◽  
X Ray Diffraction ◽  
Placer Gold ◽  
Outermost Surface ◽  
Mohs Hardness ◽  
Cell Data ◽  
Unit Cell Data

Aurihydrargyrumite, a natural Au6Hg5 phase, was found in Iyoki, Uchiko, Ehime Prefecture, Shikoku Island, Japan. Aurihydrargyrumite with a metallic silver luster occurs as a submicron- to 2 μm-thick layer on the outermost surface of the placer gold. A prismatic face may be formed by {001} and {100} or {110}. The streak is also silver white and its Mohs hardness value is ca. 2.5. Its tenacity is ductile and malleable, and its density, as calculated based on the empirical formula and powder unit-cell data, is 16.86 g·cm−3. The empirical formula of aurihydrargyrumite, on the basis of 11 Au + Hg, is Au5.95Hg5.05. Aurihydrargyrumite is hexagonal, P63/mcm, with the lattice parameters a = 6.9960(10) Å, c = 10.154(2) Å and V = 430.40(15) Å3, which is identical with the synthetic Au6Hg5 phase. The seven strongest lines in the powder X-ray diffraction (XRD) pattern [d in Å(I/I0)(hkl)] were 2.877(29)(112), 2.434(42)(113), 2.337(100)(104), 2.234(87)(211), 1.401(39)(314), 1.301(41)(404), and 1.225(65)(217). Aurihydrargyrumite forms through the weathering of mercury-bearing placer gold by involvement of self-electrorefining. This new mineral has been approved by the IMA-CNMNC (2017-003) and it is named for its composition, being a natural amalgam of gold (Latin: aurum) and mercury (Latin: hydrargyrum).

scholarly journals Gobelinite, the Co analogue of ktenasite from Cap Garonne, France, and Eisenzecher Zug, Germany

2020 ◽  
Vol 32 (6) ◽  
pp. 637-644
Author(s):  
Stuart J. Mills ◽  
Uwe Kolitsch ◽  
Georges Favreau ◽  
William D. Birch ◽  
Valérie Galea-Clolus ◽  
...  
Keyword(s):  
Empirical Formula ◽  
Old French ◽  
New Mineral ◽  
Monoclinic Space Group ◽  
X Ray Diffraction ◽  
X Ray ◽  
Structure Determinations ◽  
Jahn Teller ◽  
Mohs Hardness ◽  
Pale Green

Abstract. The new mineral gobelinite, ideally CoCu4(SO4)2(OH)6⚫6H2O, is a new member of the ktenasite group and the Co analogue of ktenasite, ZnCu4(SO4)2(OH)6⚫6H2O. It occurs at Cap Garonne (CG), Var, France (type locality), and Eisenzecher Zug (EZ), Siegerland, North Rhine-Westphalia, Germany (cotype locality). The mineral forms pale green, bluish green or greyish green, blocky to thin, lath-like crystals. They are transparent and non-fluorescent, with a vitreous, sometimes also pearly, lustre and a white streak having a pale-green cast. Mohs hardness is about 2.5. The crystals are brittle with an irregular fracture; no cleavage was observed. D(meas.) is 2.95(2) and D(calc.) is 2.907 g cm−3 (for empirical formula, CG). Common associates are brochantite and various other hydrated metal sulfates. Electron-microprobe analyses of the CG material yielded (wt. %) CuO 42.45, CoO 6.58, NiO 3.37, ZnO 3.14, SO3 22.12, and H2O 22.62 (calculated on structural grounds), and total = 100.30 wt. %, giving the empirical formula (based on 20 O atoms) (Co0.63Ni0.32Zn0.28Cu3.83)Σ5.06S1.98O20H18.00. The simplified formula is (Co,Ni)(Cu,Zn)4(SO4)2(OH)6⚫6H2O, and the endmember formula is CoCu4(SO4)2(OH)6⚫6H2O. Scanning electron microscopy–energy dispersive X-ray spectroscopy (SEM–EDS) analyses of the (Zn-free) EZ material gave the simplified average formula (Co0.92Ni0.21Mg0.01Cu3.79)Σ4.93(SO4)2.08(OH)6⚫6H2O. Optically, gobelinite (CG) is biaxial negative, with α=1.576(2), β=1.617(2) and γ=1.630(2); 2Vmeas=58(4)∘ and 2Vcalc=57.5∘. Dispersion is weak, r>v; orientation is X=β, Y=γ and Z≈α, with strong pleochroism X equaling colourless, Y equaling green and Z equaling pale green. The mineral is monoclinic, space group P21∕c, with a=5.599(1), b=6.084(1), c=23.676(5) Å, β=95.22(3)∘ and V=803.2(3) Å3 (at 100 K; CG) and a=5.611(1), b=6.103(1), c=23.808(5) Å, β=95.18(3)∘ and V=811.9(3) Å3 (at 298 K; EZ), respectively (Z=2). The eight strongest measured powder X-ray diffraction lines (d in Å (I) hkl (CG material)) are 11.870 (100) 002, 5.924 (40) 004, 4.883 (10) 102, 4.825 (15) 013, 3.946 (15) 006, 2.956 (15) 008, 2.663 (20) 202 and 2.561 (15) 1‾23. Single-crystal structure determinations gave R1=0.0310 (CG) and 0.0280 (EZ). The atomic arrangement is based on brucite-like sheets formed from edge-sharing, Jahn–Teller-distorted (4+2 coordination) CuO6 octahedra. These sheets are decorated on both sides with SO4 tetrahedra and linked via hydrogen bonds to interstitial, fairly regular Co(H2O)6 octahedra. The name alludes to the Old French word gobelin, equivalent to the German word kobold, from which the designation of the element cobalt was derived.

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.

Taneyamalite, (Na,Ca)(Mn2+,Mg,Fe3+,Al)12Si12 (O,OH)44, a new mineral from the Iwaizawa mine, Saitama Prefecture, Japan

1981 ◽  
Vol 44 (333) ◽  
pp. 51-53 ◽  
Author(s):  
Satoshi Matsubara
Keyword(s):  
Empirical Formula ◽  
Unit Cell ◽  
Refractive Indices ◽  
New Mineral ◽  
Manganese Ore ◽  
Ore Deposit ◽  
X Ray ◽  
Light Yellow ◽  
Cell Data ◽  
Unit Cell Data

AbstractTaneyamalite, (Na,Ca)(Mn2+,Mg,Fe3+,Al)12 Si12(O,OH)44, is a Mn2+-dominant analogue of howieite, and has been found in the metamorphosed bedded manganese ore deposit of the lwaizawa mine, Saitama Prefecture, Japan. It is triclinic, P1 or P, a 10.198(1), b 9.820(1), c 9.485(1) Å, α 90° 30(1)′, β 70° 32(1)′, γ 108° 34(1)′, Z = 1. The strongest X-ray powder diffractions are: 9.29(80)010, 7.99(35)10, 4.62(50)020, 3.65(40)120, 3.273(100)30, 3.081(50)11, 2.790(35)31, 2.630(28)023, 2.216(35)014, 43. Taneyamalite occurs in association with minor bannisterite as small seams in a caryopilite mass or as a fissure mineral cutting a hematite-quartz mass. It is greenish grey-yellow, lustre vitreous. Streak light yellow. Cleavage {010}, perfect. H. (Mohs) about 5. Calculated sp. gr. 3.30 (on unit cell data and normalized empirical formula), 3.25 (after the Gladstone-Dale Law using the revised data of Mandarino, 1976). It is optically biaxial negative, 2Vα about 70°. The refractive indices: α = 1.646(2), β = 1.664(2), γ = 1.676(2). Extinction is nearly parallel, sign of elongation positive. Pleochroism distinct: α = β nearly colourless, γ pale yellow. Absorption: α ≈ β < γ.

Ferroefremovite, (NH4)2Fe2+2(SO4)3, a new mineral from Solfatara di Pozzuoli, Campania, Italy

2020 ◽  
Author(s):  
Anatoly V. Kasatkin ◽  
Jakub Plášil ◽  
Radek Škoda ◽  
Italo Campostrini ◽  
Nikita V. Chukanov ◽  
...  
Keyword(s):  
Raman Spectrum ◽  
Chemical Composition ◽  
Electron Microprobe ◽  
Empirical Formula ◽  
New Mineral ◽  
Volcanic Complex ◽  
X Ray Diffraction ◽  
Cubic Crystals ◽  
X Ray ◽  
Mohs Hardness

ABSTRACT The new sulfate mineral ferroefremovite, ideally (NH4)2Fe2+2(SO4)3, was discovered at the “Bocca Grande” fumarole, Solfatara di Pozzuoli, Flegrean Volcanic Complex, Naples Province, Campania, Italy. Associated minerals are adranosite, adranosite-(Fe), godovikovite, huizingite-(Al), mascagnite, and opal. Ferroefremovite forms cubic crystals up to 0.1 mm across. The new mineral is colorless and has a vitreous luster and white streak. It is brittle and has an uneven fracture. No cleavage or parting are observed. Mohs hardness is 2. Dmeas. = 2.69(1) g/cm3. Dcalc. = 2.700 g/cm3. Optically, ferroefremovite is isotropic, n = 1.574(3) (λ = 589 nm). It is non-pleochroic. The presence of the NH4+ cation is confirmed by the Raman spectrum. The chemical composition of ferroefremovite is (wt.%; electron microprobe, N determined by CNH analysis) (NH4)2O 11.51, Na2O 0.11, K2O 1.35, MgO 8.38, MnO 0.98, FeO 18.94, SO3 57.08, total 98.35. The empirical formula based on 12 O apfu is [(NH4)1.85K0.12Na0.01]Σ1.98(Fe2+1.11Mg0.87Mn0.06)Σ2.04S2.99O12. Ferroefremovite is cubic, space group P213, with a = 10.0484(9) Å, V = 1014.59(16) Å3, and Z = 4. The strongest lines of the powder X-ray diffraction pattern [d, Å (I, %) (hkl)] are 5.80 (40) (111), 4.50 (20) (201, 210), 4.11 (30) (211), 3.17 (100) (310, 301), 3.02 (20) (311), 2.68 (50) (312, 321), 1.86 (18) (502, 432), 1.62 (18) (523, 532, 611).

Ferro-fluoro-edenite, a new amphibole endmember from Vulcano Island (Sicily, Italy)

2021 ◽  
Vol 59 (4) ◽  
pp. 741-749
Author(s):  
Italo Campostrini ◽  
Francesco Demartin ◽  
Pietro Vignola ◽  
Federico Pezzotta
Keyword(s):  
Empirical Formula ◽  
Structure Refinement ◽  
Broad Band ◽  
Monoclinic Space Group ◽  
X Ray Diffraction ◽  
Cation Site ◽  
Vulcano Island ◽  
Mohs Hardness ◽  
Cell Data ◽  
Fossa Crater

ABSTRACT Ferro-fluoro-edenite, ideally NaCa2Fe2+5(Si7Al)O22F2, was found as prismatic crystals up to 1.00 mm inside cavities in ejecta of the 1873 eruption at La Fossa crater, Vulcano Island, Aeolian Archipelago, Sicily, Italy. It is associated with quartz, magnetite, and vonsenite. Crystals are dark brown to black, transparent or semitransparent with vitreous luster, and non fluorescent. The Mohs hardness is 5–6. Cleavage is fair on {110} and fracture is uneven. Density (calc.) is 3.358 g cm–3 using the empirical formula and single-crystal cell data. The mineral is biaxial negative, α = 1.629(2), β = 1.659(2), γ = 1.667(2), 2V (calc.) = –53.8°, Y = b. Dispersion is weak to very weak, r &lt; v, pleochroism not visible. Ferro-fluoro-edenite is monoclinic, space group C2/m, a = 9.9132(10), b = 18.1736(19), c = 5.2943(6) Å, β = 104.85(1)°, V = 922.0(2) Å3, Z = 2. The strongest X-ray diffraction peaks in the powder pattern are [d(I, hkl)]: 8.54(100, 1 1 0), 4.506(16, 0 4 0), 3.154(52, 3 1 0), 2.833(43, 3 3 0), 2.057(14, 2 0 2), 1.910(12, 5 1 0), 1.662(15, 4 6 1). The FTIR spectrum shows a broad band at about 950 cm–1 and no bands in the OH stretching region. The structure refinement led to a final R = 0.0210 for 1444 observed reflections with I &gt; 2σ(I) and allowed cation site assignment and ordering. Microprobe analysis gave the following empirical formula calculated on the basis of 24 (O + F + Cl) apfu: (Na0.69K0.23□0.08)(Ca1.69Mg0.16Mn0.10Na0.05)Σ2(Fe2+2.86Mg2.04Ti0.10)Σ5(Si6.93Al1.05Ti0.02)Σ8O22(F1.89Cl0.09OH0.02)Σ2.

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.

Byrudite, (Be,〈)(V3+,Ti)3O6, a new mineral from the Byrud emerald mine, South Norway

2015 ◽  
Vol 79 (2) ◽  
pp. 261-268 ◽  
Author(s):  
G. Raade ◽  
T. Balić-Žunić ◽  
C. J. Stanley
Keyword(s):  
Empirical Formula ◽  
Secondary Ion Mass Spectrometry ◽  
Inverse Correlation ◽  
New Mineral ◽  
X Ray Diffraction ◽  
Mohs Hardness ◽  
Ore Mineralogy ◽  
Secondary Ion ◽  
Reflectance Data ◽  
Strong Inverse Correlation

AbstractByrudite (IMA 2013-045, Raade et al., 2013), with simplified formula (Be,〈)(V3+,Ti)3O6, occurs in emerald-bearing syenitic pegmatites of Permian age at Byrud farm, Eidsvoll, Akershus, South Norway. It has a norbergite-type structure, Pnma, with a = 9.982(1), b = 8.502(1), c = 4.5480(6) Å, V = 385.97(9) Å3, Z = 4. The structure was refined to R1 = 0.045 for 1413 unique reflections. Twinning occurs on {210}. The occupancy of the tetrahedral Be site refined to 0.84(1). The presence of Be was verified by secondary ion mass spectrometry but could not be quantified. Electron-microprobe analyses of the crystal used for structure determination gave the empirical formula (Be0.84〈0.16) (V1.323+Ti1.25Cr0.29Fe0.09Al0.07)Σ3.02O6. There is a strong inverse correlation between V and Cr. The ideal endmember formula is BeV23+TiO6. The mineral is black and opaque with a metallic lustre. Reflectance data in air are reported from 400 to 700 nm. The Commission on Ore Mineralogy required wavelengths are [R1, R2(λ in nm)]:16.6,17.5(470), 16.7,17.9(546), 16.8,18.3(589) and 16.8,18.6(650). The Mohs hardness is ∼7, based on indentation measurements. The mineral is brittle with an uneven fracture; cleavage is not present. D(calc.) = 4.35 g cm–3 for the empirical formula with 0.84 Be a.p.f.u. The strongest reflections of the calculated powder X-ray diffraction pattern are [d in Å (Irel)(hkl)]: 3.721(72)(111), 2.965(100)(121), 2.561(50)(311), 2.464(41)(230), 2.167(24)(231), 1.681(34)(402), 1.671(66)(232), 1.435(23)(630).

Pampaloite, AuSbTe, a new mineral from Pampalo gold mine, Finland

2018 ◽  
Vol 83 (03) ◽  
pp. 393-400
Author(s):  
Anna Vymazalová ◽  
Kari Kojonen ◽  
František Laufek ◽  
Bo Johanson ◽  
Chris J. Stanley ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Empirical Formula ◽  
Mean Value ◽  
New Mineral ◽  
Monoclinic Space Group ◽  
Gold Mine ◽  
X Ray Diffraction ◽  
Synthetic Material ◽  
X Ray ◽  
Mohs Hardness

AbstractPampaloite, AuSbTe, is a new mineral discovered in the Pampalo gold mine, 65 km east of Joensuu, Finland. It forms anhedral grains (up to ~20 μm) intergrown with gold, frohbergite and altaite. Pampaloite is brittle and has a metallic lustre. Values of VHN25 lie between 245 and 295 kg/mm2, with a mean value of 276 kg/mm2, corresponding to a Mohs hardness of ~4–5 (measured on synthetic material). In plane-polarised light, pampaloite is white with medium to strong bireflectance, weak reflectance pleochroism from slightly pinkish brown to slightly bluish white (only visible in grains of synthetic material containing multiple orientations), and strong anisotropy, with blue to light brown rotation tints; it exhibits no internal reflections. Reflectance values of pampaloite in air (R1, R2 in %) are: 60.0, 62.5 at 470 nm, 62.5, 64.8 at 546 nm, 63.2, 65.6 at 589 nm and 63.7, 66.0 at 650 nm. Ten electron-microprobe analyses of natural pampaloite give an average composition: Au 44.13, Sb 27.44 and Te 28.74, total 100.31 wt.%, corresponding to the empirical formula Au1.00Sb1.00Te1.00 based on 3 atoms; the average of eleven analyses on synthetic pampaloite is: Au 44.03, Sb 27.26, and Te 29.08, total 100.38 wt.%, corresponding to Au0.99Sb1.00Te1.01. The density, calculated on the basis of the empirical formula, is 9.33 g/cm3.The mineral is monoclinic, space group C2/c, with a = 11.947(3), b = 4.481(1) Å, c = 12.335(3) Å, β = 105.83(2)°, V = 635.3(3) Å3 and Z = 8. The crystal structure was solved and refined from the single-crystal X-ray-diffraction data of synthetic AuSbTe. The pampaloite crystal structure can be considered as a monoclinic derivative of the CdI2 structure composed of [AuTe3Sb3] octahedra. The strongest lines in the powder X-ray diffraction pattern of synthetic pampaloite [d in Å (I) (hkl)] are: 4.846(24)($\bar{2}$02), 3.825(18)(111), 2.978(100)($\bar{3}$11), 2.968(50)(004), 2.242(25)(020), 2.144(55)(313), 2.063(33)($\bar{3}$15) and 1.789(18)(024).

Barlowite, Cu4FBr(OH)6, a new mineral isotructural with claringbullite: description and crystal structure

2014 ◽  
Vol 78 (7) ◽  
pp. 1755-1762 ◽  
Author(s):  
Peter Elliott ◽  
Mark A. Cooper ◽  
Allan Pring
Keyword(s):  
Empirical Formula ◽  
Small Variation ◽  
New Mineral ◽  
Charge Balance ◽  
X Ray Diffraction ◽  
X Ray ◽  
New Mineral Species ◽  
Perfect Cleavage ◽  
Mohs Hardness ◽  
Hexagonal Crystals

AbstractThe new mineral species barlowite, ideally Cu4FBr(OH)6, has been found at the Great Australia mine, Cloncurry, Queensland, Australia. It is the Br and F analogue of claringbullite. Barlowite forms thin blue, platy, hexagonal crystals up to 0.5 mm wide in a cuprite-quartz-goethite matrix associated with gerhardtite and brochantite. Crystals are transparent to translucent with a vitreous lustre. The streak is sky blue. The Mohs hardness is 2–2.5. The tenacity is brittle, the fracture is irregular and there is one perfect cleavage on {001}. Density could not be measured; the mineral sinks in the heaviest liquid available, diluted Clerici solution (D &3.8 g/cm3). The density calculated from the empirical formula is 4.21 g/cm3. Crystals are readily soluble in cold dilute HCl. The mineral is optically non-pleochroic and uniaxial (–). The following optical constants measured in white light vary slightly suggesting a small variation in the proportions of F, Cl and Br: ω 1.840(4)–1.845(4) and ε 1.833(4)–1.840(4). The empirical formula, calculated on the basis of 18 oxygen atoms and H2O calculated to achieve 8 anions and charge balance, is Cu4.00F1.11Br0.95Cl0.09(OH)5.85. Barlowite is hexagonal, space group P63/mmc, a = 6.6786(2), c = 9.2744(3) Å , V = 358.251(19) Å3, Z = 2. The five strongest lines in the powder X-ray diffraction pattern are [d(Å )(I)(hkl)]: 5.790(100)(010); 2.889(40)(020); 2.707(55)(112); 2.452(40)(022); 1.668(30)(220).

Tapiaite, Ca5Al2(AsO4)4(OH)4·12H2O, a new mineral from the Jote mine, Tierra Amarilla, Chile

2015 ◽  
Vol 79 (2) ◽  
pp. 345-354 ◽  
Author(s):  
Anthony R. Kampf ◽  
Stuart J. Mills ◽  
Barbara P. Nash ◽  
Maurizio Dini ◽  
Arturo A. Molina Donoso
Keyword(s):  
Empirical Formula ◽  
New Mineral ◽  
X Ray Diffraction ◽  
Unit Cell Parameters ◽  
Calculated Density ◽  
X Ray ◽  
Cell Parameters ◽  
Interlayer Region ◽  
Mohs Hardness ◽  
Thick Layers

AbstractTapiaite (IMA2014-024), Ca5Al2(AsO4)4(OH)4·12H2O, 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, joteite, 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 colourless blades, flattened on {101} and elongated and striated along [010], up to ∼0.5 mm long, and exhibiting the forms {101}, {101} and {111}. The blades are commonly intergrown in subparallel bundles and less commonly in sprays. The mineral is transparent and has a white streak and vitreous lustre. The Mohs hardness is estimated to be between 2 and 3, the tenacity is brittle, and the fracture is splintery. It has two perfect cleavages on {101} and {101}. The calculated density based on the empirical formula is 2.681 g cm–3. It is optically biaxial (+) with α = 1.579(1), β = 1.588(1), γ = 1.610(1) (white light), 2Vmeas = 66(2)° and 2Vcalc = 66°. The mineral exhibits no dispersion. The optical orientation is X ≈ [101]; Y = b, Z ≈ [101]. The electron-microprobe analyses (average of five) provided: Na2O 0.09, CaO 24.96, CuO 0.73, Al2O3 10.08, Fe2O3 0.19, As2O5 40.98, Sb2O5 0.09, H2 O 23.46 (structure), total 100.58 wt.%. In terms of the structure, the empirical formula (based on 32 O a.p.f.u.) is (Ca4.83Cu0.102+Na0.03)Σ4.96(Al2.14Fe0.033+)Σ2.17[(As3.875+Sb0.015+)Σ3.88O16][(OH)3.76(H2O)0.24]Σ4(H2O)10·2H2O. The mineral is easily soluble in RT dilute HCl. Tapiaite is monoclinic, P21/n, with unit-cell parameters a = 16.016(1), b = 5.7781(3), c = 16.341(1) Å, β = 116.704(8)°, V = 1350.9(2) Å3 and Z = 2. The eight strongest lines in the powder X-ray diffraction pattern are [dobs Å(I)(hkl)]: 13.91(100)(101), 7.23(17)(200,002), 5.39(22)(110,011), 4.64(33)(112,211,303), 3.952(42)(113,311,213), 3.290(35)(214,412,114,411), 2.823(39)(303,315) and 2.753(15)(513,115,121,511). The structure of tapiaite (R1 = 5.37% for 1733 Fo > 4σF) contains Al(AsO4)(OH)2 chains of octahedra and tetrahedra that are topologically identical to the chain in the structure of linarite. CaO8 polyhedra condense to the chains, forming columns, which are decorated with additional peripheral AsO4 tetrahedra. The CaO8 polyhedra in adjacent columns link to one another by corner-sharing to form thick layers parallel to {101} and the peripheral AsO4 tetrahedra link to CaO6 octahedra in the interlayer region, resulting in a framework structure.

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