Skaergaardite, PdCu, a new platinum-group intermetallic mineral from the Skaergaard intrusion, Greenland

2004 ◽  
Vol 68 (4) ◽  
pp. 615-632 ◽  
Author(s):  
N. S. Rudashevsky ◽  
A. M. McDonald ◽  
L. J. Cabri ◽  
T. F. D. Nielsen ◽  
C. J. Stanley ◽  
...  
Keyword(s):  
New Mineral ◽  
Indentation Hardness ◽  
Skaergaard Intrusion ◽  
East Greenland ◽  
X Ray ◽  
Cscl Type ◽  
Black Streak ◽  
Cscl Structure ◽  
Cubic Structure ◽  
Micro Indentation

AbstractSkaergaardite, PdCu, is a new mineral discovered in the Skaergaard intrusion, Kangerdlugssuaq area, East Greenland. It occurs in a tholeitiic gabbro associated with plagioclase, clinopyroxene, orthopyroxene, ilmenite, titanian magnetite, fayalite and accessory chlorite-group minerals, ferrosaponite, a member of the annite–phlogopite series, hornblende, actinolite, epidote, calcite, ankerite, apatite and baddeleyite. The mineral is found in composite microglobules composed of bornite, chalcocite, digenite, chalcopyrite, with rare cobalt pentlandite, cobaltoan pentlandite, sphalerite, keithconnite, vasilite, zvyagintsevite, (Cu,Pd,Au) and Pt-Fe-Cu-Pd alloys, unnamed PdCu3, (Pd,Cu,Sn), Au3Cu and PdAuCu. Skaergaardite occurs as droplets, equant grains with rounded outlines, subhedral to euhedral crystals and as irregular grains that vary in size from 2 to 75 μm, averaging 22 μm. It is steel grey with a bronze tint, has a black streak, a metallic lustre and is sectile. Neither cleavage nor fracture was observed. The mineral has a micro-indentation hardness of VHN25 = 257. It is isotropic, non-pleochroic and exhibits neither discernible internal reflections nor evidence of twinning. Skaergaardite varies from bright creamy white (associated with bornite and chalcopyrite) to bright white (associated with digenite and chalcocite). Reflectance values in air (and in oil) are: 58.65 (47.4) at 470 nm, 62.6 (51.1) at 546 nm, 64.1 (52.8) at 589 nm and 65.25 (53.95) at 650 nm. The average of 311 electron-microprobe analyses gives: Pd 58.94, Pt 1.12, Au 2.23, Cu 29.84, Fe 3.85, Zn 1.46, Sn 1.08, Te 0.28 and Pb 0.39, total 99.19 wt.%, corresponding to (Pd0.967Au0.020Pt0.010)Σ0.997(Cu0.820Fe0.120 Zn0.039Sn0.016Te0.004Pb0.003)Σ1.002. The mineral is cubic, space group Pm3m, a = 3.0014(2) Å, V = 27.0378 Å3, Z = 1. Dcalc is 10.64 g/cm3. The six strongest lines in the X-ray powder-diffraction pattern [d in Å (I)(hkl)] are: 2.122(100)(110), 1.5000(20)(200), 1.2254(50)(211), 0.9491(20)(310), 0.8666(10)(222), 0.8021(70)(321). The mineral has the CsCl-type structure. It is believed to be isostructural with wairauite (CoFe), synthetic CuZn (β-brass) and is structurally related to hongshiite (PtCu). Skaergaardite developed from a disordered Pd-Cu-rich metal alloy melt that had exsolved from an earlier Cu-(Fe) sulphide melt. Ordering of Pd and Cu (beginning at T ≈ 600°C) results in development of the CsCl structure from a disordered face-centred cubic structure.

The new mineral insizwaite (PtBi2) and new data on niggliite (PtSn)

1972 ◽  
Vol 38 (299) ◽  
pp. 794-800 ◽  
Author(s):  
L. J. Cabri ◽  
D. C. Harris
Keyword(s):  
New Mineral ◽  
Indentation Hardness ◽  
X Ray Diffraction ◽  
X Ray ◽  
Reflected Light ◽  
D 12 ◽  
Probable Space ◽  
Micro Indentation ◽  
Hardness Values ◽  
Reflectance Measurements

SummaryInsizwaite from Waterfall Gorge, Insizwa, is a new mineral with the composition Pt1·00Bi1·35Sb0·57. The name is for the locality and is to be applied to the end member PtBi2. The analysed material is an antimonian variety. The mineral is cubic, the unit-cell for the antimonian variety has a 6·625 (2) Å, probable space group Pa3, calc. D 12·8 g/cm3. The strongest lines on the X-ray diffraction powder pattern are: 2·96 (8) 210; 2·70 (8) 211; 2·34 (5) 220; 1·99 (10 311; 1·774 (7) 321; 1·433 (5) 421; 1·277 (6) 511, 333; 1·171 (6) 440; and 0·862 (7) 731. Under reflected light the mineral is white (in air and in oil) and is isotropic. Reflectance measurements at 470, 546, 589, and 650 nm gave 61·1, 60·0, 60·6, and 61·7 %. Micro-indentation hardness values range from 488 to 540 (av. 519) kg/mm2 with a 25 g load.New data are presented for niggliite from the type locality and for synthetic PtSn.

Benleonardite, a new mineral from the Bambolla mine, Moctezuma, Sonora, Mexico

1986 ◽  
Vol 50 (358) ◽  
pp. 681-686 ◽  
Author(s):  
C. J. Stanley ◽  
A. J. Criddle ◽  
J. E. Chisholm
Keyword(s):  
Polarized Light ◽  
Visible Spectrum ◽  
New Mineral ◽  
Indentation Hardness ◽  
Calculated Density ◽  
X Ray ◽  
New Mineral Species ◽  
Average Analysis ◽  
Native Silver ◽  
Micro Indentation

AbstractBenleonardite, ideally Ag8(Sb,As)Te2S3 with Sb > As, is a new mineral species that occurs in ore specimens collected from the dumps of the disused Bambolla mine, Moctezuma, Mexico. The associated minerals are acanthite, hessite, an unnamed Ag4TeS phase, pyrite, sphalerite, and native silver. Together with benleonardite, these form thin black crusts in fractures filled with quartz and dolomite in highly altered, tuffaceous, andesitic and rhyolitic rocks. Benleonardite is an opaque mineral and, in reflected plane-polarized light in air, it is weakly bireflectant from very pale light blue to slightly darker blue. It is not pleochroic. Luminance values (relative to the CIE illuminant C) for Ro and R′e computed from visible spectrum reflectance data for the most bireflectant grain, are 33.6 and 31.7% in air, and 18.3 and 16.5% in Zeiss oil (ND 1.515) respectively. Vickers micro-indentation hardness is 105–125 (VHN25). The X-ray powder diffraction pattern could be indexed on a tetragonal cell with a 6.603(5) and c 12.726(6) Å; for Z = 2, the calculated density is 7.79 g/cm2 for the average analysis. The strongest five lines in the X-ray powder pattern are [d in Å (I) (hkl): 12.7 (70) (001); 3.188 (30) (021,004); 2.936 (100) (022); 2.608 (35) (023); 2.158 (35) (124).

Kalungaite, PdAsSe, a new platinum-group mineral from the Buraco do Ouro gold mine, Cavalcante, Goiás State, Brazil

2006 ◽  
Vol 70 (1) ◽  
pp. 123-130 ◽  
Author(s):  
N. F. Botelho ◽  
M. A. Moura ◽  
R. C. Peterson ◽  
C. J. Stanley ◽  
D. V. G. Silva
Keyword(s):  
Group Element ◽  
New Mineral ◽  
Indentation Hardness ◽  
Gold Mine ◽  
Peraluminous Granite ◽  
X Ray ◽  
Reflected Light ◽  
Ore Minerals ◽  
Platinum Group ◽  
Micro Indentation

AbstractKalungaite, PdAsSe, is a new mineral discovered in the Buraco do Ouro gold mine, Cavalcante town, Goiás State, Brazil. It occurs in a quartz-muscovite mylonite, related to a peraluminous granite, in platy anhedral aggregates along foliation planes. Associated ore minerals are gold, chalcopyrite, bohdanowiczite, an unnamed Pb-Bi-Se-S mineral, clausthalite, guanajuatite, stibiopalladinite, sperrylite and padmaite. Gangue minerals are muscovite, quartz and rare tourmaline and magnetite. Kalungaite is lead-grey, has a metallic lustre, a black streak and is brittle with uneven fracture. No cleavage was observed. The mineral has a micro-indentation hardness of VHN25 = 438 (range of 429–455 kg/mm2 from five indentations). Under reflected light, kalungaite is cream, or creamy grey adjacent to gold grains, has no internal reflections and is isotropic. Reflectance values in air (and in oil) are: 47.5 (33.3) at 470 nm, 46.9 (32.6) at 546 nm, 46.8 (32.6) at 589 nm and 48.0 (34.0) at 650 nm. The average of eight electron-microprobe analyses gives: Pd 41.32, As 27.49, Bi 0.35, Sb 1.59, Se 27.67 and S 1.22, total 99.64 wt. %, corresponding to Pd1.006(As0.950Sb0.034Bi0.004)Σ0.988(Se0.908S0.099)Σ1.007Kalungaite is cubic, space group Pa, a = 6.089(4) Å, V = 225.78 Å3, Z = 4. Dcalc is 7.59 g/cm3. The strongest seven X-ray powder-diffraction lines [d in Å(I)(hkl)] are: 3.027(75)(002), 1.838(100)(113), 1.172(95)(115, 333), 1.077(80)(044, 144, 334), 0.988(70)(116, 235, 253), 0.929(90)(335) and 0.918(70)(226). Kalungaite is interpreted as having formed from hydrothermal fluids of granitic origin, during syn-emplacement shearing and alteration, producing an unusual gold-platinum-group element deposit.

Naldrettite, Pd2Sb, a new intermetallic mineral from the Mesamax Northwest deposit, Ungava region, Québec, Canada

2005 ◽  
Vol 69 (1) ◽  
pp. 89-97 ◽  
Author(s):  
L. J. Cabri ◽  
A. M. McDonald ◽  
C. J. Stanley ◽  
N. S. Rudashevsky ◽  
G. Poirier ◽  
...  
Keyword(s):  
New Mineral ◽  
Indentation Hardness ◽  
Fold Belt ◽  
Orthorhombic Space Group ◽  
Equivalent Circle Diameter ◽  
Sulphide Minerals ◽  
Polysynthetic Twinning ◽  
Monoclinic Pyrrhotite ◽  
Micro Indentation ◽  
Circle Diameter

AbstractNaldrettite, Pd2Sb, is a new intermetallic mineral discovered in the Mesamax Northwest deposit, Cape Smith fold belt, Ungava region, northern Québec. It is associated with monoclinic pyrrhotite, pentlandite, chalcopyrite, galena, sphalerite, cobaltite, clinochlore, magnetite, sudburyite (PdSb), electrum and altaite. Other rarer associated minerals include a second new mineral (ungavaite, Pd4Sb3), sperrylite (PtAs2), michenerite (PdBiTe), petzite (Ag3AuTe4) and hessite (Ag2Te). Naldrettite occurs as anhedral grains, which are commonly attached or moulded to sulphide minerals, and also associated with clinochlore. Grains of naldrettite vary in size (equivalent circle diameter) from ~10 to 239 μm, with an average of 74.4 mm (n = 632). Cleavage was not observed and fracture is irregular. The mineral has a mean micro-indentation hardness of 393 kg/mm2. It is distinctly anisotropic, non-pleochroic, has weak bireflectance, and does not exhibit discernible internal reflections. Some grains display evidence of strain-induced polysynthetic twinning. Naldrettite appears bright creamy white in association with pentlandite, pyrrhotite, clinochlore and chalcopyrite. Reflectance values in air (and in oil) for R1 and R2 are: 49.0, 50.9 (35.9, 37.6) at 470 nm, 53.2, 55.1 (40.3, 42.1) at 546 nm, 55.4, 57.5 (42.5, 44.3) at 589 nm and 58.5, 60.1 (45.4, 47.2) at 650 nm. The average of 69 electron-microprobe analyses on 19 particles gives: Pd 63.49, Fe 0.11, Sb 35.75, As 0.31, and S 0.02, total 99.68 wt.%, corresponding to (Pd1.995Fe0.007)2.002(Sb0.982AS0.014S0.002)0.998. The mineral is orthorhombic, space group Cmc21, a 3.3906(1), b 17.5551(5), c 6.957(2) Å , V 414.097(3) Å3, Z = 8. Dcalc is 10.694(1) g/cm3. The six strongest lines in the X-ray powder-diffraction pattern [d in Å (I)(hkl)] are: 2.2454(100)(132), 2.0567(52)(043), 2.0009(40)(152), 1.2842(42)(115), 1.2122(50)(204) and 0.8584(56)(1.17.4).

Feinglosite, a new mineral related to brackebuschite, from Tsumeb, Namibia

1997 ◽  
Vol 61 (405) ◽  
pp. 285-289 ◽  
Author(s):  
A. M. Clark ◽  
A. J. Criddle ◽  
A. C. Roberts ◽  
M. Bonardi ◽  
E. A. Moffatt
Keyword(s):  
Visible Spectrum ◽  
New Mineral ◽  
Monoclinic Space Group ◽  
Indentation Hardness ◽  
Calculated Density ◽  
Reflected Light ◽  
The Mean ◽  
Micro Indentation ◽  
Reflectance Data ◽  
The Ideal

AbstractFeinglosite, the zinc analogue of arsenbrackebuschite, was found lining a cavity in a sample of massive chalcocite from Tsumeb, Namibia. In this cavity it is associated with wulfenite, anglesite and goethite. The mean of seven electron-microprobe analyses (wt.%) is: PbO 61.4, ZnO 7.3, FeO 1.8, As2O5 22.1, SO3 5.3, H2O (by difference) [2.1], total = [100.00]%, leading to the ideal formula: Pb2(Zn,Fe)[(As,S)O4]·H2O. Feinglosite is monoclinic, space group P21 or P21/m, a 8.973(6), b 5.955(3), c 7.766(6) Å, β 112.20(6)°, with Z = 2. The strongest five reflections of the X-ray powder diffraction pattern are [d in Å (I) (hkl)]: 4.85 (50) (110), 3.246 (100) (112), 2.988 (60) (301), 2.769 (60) (300/211), 2.107 (50) (321). The mineral is pale olive-green, transparent, sectile, and has a white streak and adamantine lustre. It overgrows clusters of goethite crystals and forms globular microcrystalline aggregates up to 0.5–0.75mm in size. The hardness on Mohs' scale is 4–5: the mean micro-indentation hardness is 263 at VHN100. Its calculated density is 6.52 g cm−3. The mineral is pale brownish grey in reflected light (when compared with goethite). Visible spectrum reflectance data are presented. Feinglosite is named for Mark N. Feinglos who first recognised the mineral on a specimen in his collection.

Cationic Self-diffusion in Solid Choline Perchlorate Studied by NMR

1997 ◽  
Vol 52 (8-9) ◽  
pp. 637-639 ◽  
Author(s):  
Hiroyuki Ishida ◽  
Masakazu Kato ◽  
Hiroshi Ono ◽  
Ryuichi Ikeda
Keyword(s):  
Phase I ◽  
Spin Relaxation ◽  
Solid Phase ◽  
Relaxation Times ◽  
X Ray ◽  
Self Diffusion ◽  
Spin Lattice ◽  
H Nmr ◽  
Cscl Type ◽  
Cubic Structure

Abstract The 1H spin-lattice and spin-spin relaxation times, and the second moment of the 1H NMR linewidth of choline Perchlorate, [(CH3)3NCH2CH2OH]ClO4, were measured in its highest-temperature solid phase, i. e. above 275 K. X-ray powder patterns taken at ca. 380 K revealed that in this phase the crystal has a CsCl-type cubic structure (a = 6.326(4) Å and Z = 1). From 1H NMR experiments it was found that the cations in this phase undergo isotropic rotation and translational self-diffusion. From the 1H T1, measurements, the activation energies of the cationic rotation and self-diffusion were evaluated to be 21.4 ± 0.4 and 62 ± 3 kJ mol-1 , respectively.

Epitaxy of Thin Ternary Co1−xFexSi2 Silicide Films on SI(111)

1998 ◽  
Vol 528 ◽  
Author(s):  
L. Khouchaf ◽  
D. Berling ◽  
V. Pierron-Bohnes ◽  
C. Pirri ◽  
S. Hong ◽  
...  
Keyword(s):  
Room Temperature ◽  
Local Environment ◽  
Type Structure ◽  
Appreciable Amount ◽  
Silicide Phase ◽  
X Ray Diffraction ◽  
X Ray ◽  
Cscl Type ◽  
Cubic Structure ◽  
X Ray Absorption

AbstractLow-energy electron diffraction, x-ray diffraction, and x-ray absorption techniques are used to investigate the atomic structure of ternary silicides (MSi2, M = Co, Fe). 100 Å thick Co1−xFexSi2 films (with 0 ≤ × ≤ 1) were grown by codeposition onto a Si(111) substrate held at room temperature. The as-deposited films are metallic and adopt an ordered cubic structure of CsCl-type with essentially random vacancies, very similar to that of room-temperature grown FeSi2 and CoSi2 silicides. Upon annealing at 650°C, Fe-rich (x ≥ 0.85) films invariably convert into a semiconducting phase with a structure similar to the orthorhombic β-FeSi2 one. Yet, most interestingly, an almost cubic structure is preserved for x ≤ 0.85. Nevertheless, x-ray diffraction reveals a demixion into a Co rich CaF2-type silicide and a Fe-rich phase with a nearly cubic α-FeSi2 type structure. Extended x-ray absorption fine structure measurements indicate a local environment of Fe atoms similar to that in CsCl-type or α-FeSi2-type structure over the whole 0 < x < 0.85 composition range, showing that Fe does not merely substitute for Co atoms in a perfect CaF2-type CoSi2 structure, even for very low Fe content. In contrast, the local environment of Co atoms is similar to that in CoSi2 for Co-rich ternary compounds. Substantial modifications around Co sites are although observed in Fe richer silicides, suggesting that for x < 0.5, an appreciable amount of Co is incorporated in the α-FeSi2-type silicide phase.

Yaroshevskite, Cu9O2(VO4)4Cl2, a new mineral from the Tolbachik volcano, Kamchatka, Russia

2013 ◽  
Vol 77 (1) ◽  
pp. 107-116 ◽  
Author(s):  
I. V. Pekov ◽  
N. V. Zubkova ◽  
M. E. Zelenski ◽  
V. O. Yapaskurt ◽  
Yu. S. Polekhovsky ◽  
...  
Keyword(s):  
Direct Methods ◽  
Structural Formula ◽  
Scoria Cone ◽  
New Mineral ◽  
Indentation Hardness ◽  
State University ◽  
Calculated Density ◽  
X Ray ◽  
Reflected Light ◽  
Tolbachik Volcano

AbstractA new mineral, yaroshevskite, ideally Cu9O2(VO4)4Cl2, occurs in sublimates collected from the Yadovitaya fumarole at the Second scoria cone of the Northern Breakthrough of the Great Tolbachik Fissure Eruption, Tolbachik volcano, Kamchatka, Russia. It is associated with euchlorine, fedotovite, hematite, tenorite, lyonsite, melanothallite, atlasovite, kamchatkite and secondary avdoninite, belloite and chalcanthite. Yaroshevskite forms isolated prismatic crystals, up to 0.1 × 0.15 × 0.3 mm in size, on the surface of euchlorine crusts. The mineral is opaque and black, with a reddish black streak and lustre between metallic and adamantine. Yaroshevskite is brittle, no cleavage was observed and the fracture is uneven. The Mohs hardness is ~3½ (corresponding to a mean VHN micro-indentation hardness of 172 kg mm -2) and the calculated density is 4.26 g cm-3. In reflected light, yaroshevskite is grey with a weak bluish hue. Pleochroism, internal reflections and bireflectance were not observed. Anisotropy is very weak. The composition (wt.%) determined by electron microprobe is: CuO 61.82, ZnO 0.53, Fe2O3 0.04, V2O531.07, As2O50.32, MoO3 1.56, Cl 6.23, O=Cl2 1.41; total 100.16. The empirical formula, calculated on the basis of 20 (O + Cl) anions is (Cu8.80 Zn0.07 Fe0.01)Σ 8.88(V3.87Mo0.12As0.03)σ 4.02O18.01Cl1.99. Yaroshevskite is triclinic, space group P, a = 6.4344(11), b = 8.3232(13), c = 9.1726(16) Å , α = 105.338(14), β = 96.113(14), γ = 107.642(1)°, V = 442.05(13) Å3 and Z = 1. The nine strongest reflections in the X-ray powder pattern [dobs in Å (I)(hkl)] are as follows: 8.65(100)(001); 6.84(83)(01); 6.01(75)(100); 5.52(60)(01); 4.965(55)(011); 4.198(67)(1); 4.055(65)(110); 3.120(55)(021); 2.896(60)(21,003,20). The crystal structure was solved by direct methods from single-crystal X-ray diffraction data and refined to R = 0.0737. The yaroshevskite structure is unique. It is based on corrugated layers made up of chains of edge-sharing flat squares with central Cu2+ cations [Cu(1), Cu(4) and Cu(5)]; neighbouring chains are connected via groups consisting of three Cu2+ -centred squares [two Cu(3) and Cu(6)]. Neighbouring layers are connected via pairs of Cu(2)O4Cl five-coordinate polyhedra and isolated VO4 tetrahedra. The structure of yaroshevskite can also be considered in terms of oxygen-centred tetrahedra: O(7)Cu4 tetrahedra are connected via common Cu(4) and Cu(5) vertices to form pyroxene-like chains [O2Cu6]∞. In this context, the structural formula can be written Cu3[O2Cu6][VO4]4Cl2. The mineral name honours the Russian geochemist Alexei A. Yaroshevsky (b. 1934) of Moscow State University.

Microstructural evolution of body-centered cubic structure related Ti–Zr–Ni phases in non-stoichiometric Zr-based Zr–Ti–Mn–V–Ni hydride electrode alloys

2003 ◽  
Vol 18 (1) ◽  
pp. 37-44 ◽  
Author(s):  
Xueyan Song ◽  
Yun Chen ◽  
Cesar Sequeira ◽  
Yongquan Lei ◽  
Qidong Wang ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Electrochemical Properties ◽  
Alloy Composition ◽  
Body Centered Cubic ◽  
Laves Phases ◽  
X Ray ◽  
Transmission Electron ◽  
Cscl Type ◽  
Cubic Structure ◽  
Tini Phase

Non-stoichiometric Zr-based alloys were prepared, and the corresponding electrochemical properties were characterized as hydride electrode alloys. The microstructure and chemical composition of non-stoichiometric Zr–Ti–Mn–V–Ni hydride electrode alloys were systematically investigated by x-ray Rietveld refinement, transmission electron microscopy (TEM), and energy dispersive spectroscopy under TEM observation. C14, C15 Laves phases and non-Laves phases were identified in Zr1−xTix(MnVNi)2.2 (x = 0, 0.2, 0.3, 0.4) alloys. Non-Laves phases in Zr1-xTix(MnVNi)2.2 (x = 0, 0.2, 0.3, 0.4) alloys are Ti–Zr–Ni phases related to the TiNi phase with pseudo-body-centered-cubic structure of the CsCl type. The evolution of crystallography and phase constitution for Ti–Zr–Ni non-Laves phases with different alloy composition was systematically studied. The influence of the Ti–Zr–Ni phases on the electrochemical properties of non-stoichiometric Zr1−xTix(MnVNi)2.2 alloys is briefly discussed.

NIOBOHEFTETJERNITE, ScNbO4, A NEW MINERAL FROM THE BEFANAMO PEGMATITE, MADAGASCAR

2021 ◽  
Author(s):  
Inna Lykova ◽  
Ralph Rowe ◽  
Glenn Poirier ◽  
Andrew M. McDonald ◽  
Gerald Giester
Keyword(s):  
Crystal Structure ◽  
Raman Spectrum ◽  
Chemical Composition ◽  
Diffraction Data ◽  
Empirical Formula ◽  
New Mineral ◽  
X Ray Diffraction ◽  
X Ray ◽  
Black Streak ◽  
Reflectance Data

ABSTRACT A new mineral, nioboheftetjernite, ideally ScNbO4, was found in the Befanamo pegmatite, Analamanga, Madagascar. It occurs as anhedral grains and very crude elongated crystals up to 200 μm in length in an intergrowth with rossovskyite, ilmenite, rutile, thortveitite, euxenite-(Y), feldspar, and quartz. The mineral is black with dark-brown to black streak and submetallic luster. It has no cleavage and its fracture is uneven. Dcalc is 5.855 g/cm3. The Raman spectrum and reflectance data are reported. The chemical composition (wt.%) is MgO 0.06, MnO 2.49, Fe2O3 12.14, Sc2O3 11.34, TiO2 5.94, SnO2 1.45, Nb2O5 32.23, Ta2O5 29.93, WO3 3.38, total 98.96. The empirical formula calculated on the basis of 4 O apfu is (Sc0.40Fe3+0.37Ti0.15Mn2+0.08)Σ1.00(Nb0.58Ta0.33W0.03Ti0.03Sn0.02)Σ0.99O4. The simplified general formula is (Sc,Fe3+)(Nb,Ta)O4. Nioboheftetjernite is monoclinic, P2/c, a = 4.7092(3), b = 5.6531(4), c = 5.0530(4) Å, β = 90.453(3)°, and V = 134.515(17) Å3. The strongest reflections of the powder X-ray diffraction pattern [d,Å(I)(hkl)] are: 4.722(22)(100), 3.776(22)(011), 3.628(44)(110), , 2.938(83)(111), 2.472(30)(021), and . The crystal structure, refined from single-crystal X-ray diffraction data (R1 = 0.016), is of the “wolframite” type. The mineral is named as the Nb-analogue of heftetjernite, ScTaO4.

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