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  • 1
    Publication Date: 2018
    Description: 〈div data-abstract-type="normal"〉〈p〉Pampaloite, 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 VHN〈span〉25〈/span〉 lie between 245 and 295 kg/mm〈span〉2〈/span〉, with a mean value of 276 kg/mm〈span〉2〈/span〉, 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 (〈span〉R〈/span〉〈span〉1,〈/span〉〈span〉R〈/span〉〈span〉2〈/span〉 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 Au〈span〉1.00〈/span〉Sb〈span〉1.00〈/span〉Te〈span〉1.00〈/span〉 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 Au〈span〉0.99〈/span〉Sb〈span〉1.00〈/span〉Te〈span〉1.01〈/span〉. The density, calculated on the basis of the empirical formula, is 9.33 g/cm〈span〉3〈/span〉.The mineral is monoclinic, space group 〈span〉C〈/span〉2/〈span〉c〈/span〉, with 〈span〉a〈/span〉 = 11.947(3), 〈span〉b〈/span〉 = 4.481(1) Å, 〈span〉c〈/span〉 = 12.335(3) Å, β = 105.83(2)°, 〈span〉V〈/span〉 = 635.3(3) Å〈span〉3〈/span〉 and 〈span〉Z〈/span〉 = 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 CdI〈span〉2〈/span〉 structure composed of [AuTe〈span〉3〈/span〉Sb〈span〉3〈/span〉] octahedra. The strongest lines in the powder X-ray diffraction pattern of synthetic pampaloite [〈span〉d〈/span〉 in Å (〈span〉I〈/span〉) (〈span〉hkl〈/span〉)] are: 4.846(24)(〈span〉〈span〉〈img data-mimesubtype="gif" data-type="simple" src="http://static.cambridge.org/resource/id/urn:cambridge.org:id:binary:20190709073523038-0660:S0026461X18001299:S0026461X18001299_inline1.gif"〉 〈span data-mathjax-type="texmath"〉 〈/span〉 〈/span〉〈/span〉02), 3.825(18)(111), 2.978(100)(〈span〉〈span〉〈img data-mimesubtype="gif" data-type="simple" src="http://static.cambridge.org/resource/id/urn:cambridge.org:id:binary:20190709073523038-0660:S0026461X18001299:S0026461X18001299_inline2.gif"〉 〈span data-mathjax-type="texmath"〉 〈/span〉 〈/span〉〈/span〉11), 2.968(50)(004), 2.242(25)(020), 2.144(55)(313), 2.063(33)(〈span〉〈span〉〈img data-mimesubtype="gif" data-type="simple" src="http://static.cambridge.org/resource/id/urn:cambridge.org:id:binary:20190709073523038-0660:S0026461X18001299:S0026461X18001299_inline3.gif"〉 〈span data-mathjax-type="texmath"〉 〈/span〉 〈/span〉〈/span〉15) and 1.789(18)(024).〈/p〉〈/div〉
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  • 2
    Publication Date: 2011-04-01
    Description: Nisnite, ideally Ni3Sn, was found during a re-examination of heazlewoodite crystals in rodingite samples from the Jeffrey mine, Asbestos, Quebec. It occurs as bronze-colored metallic, striated, blocky and square to rectangular tabular crystals of up to 100 {micro}m in length, with groupings of [≤]1 mm growing on heazlewoodite. Crystal groupings exhibit a boxwork-like habit. Reflectance measurements in air gave 43.2 (470 nm), 49.1 (546 nm), 53.2 (589 nm), and 59.0% (650 nm). Minerals closely associated with nisnite are chromite, diopside, grossular, heazlewoodite and shandite. The mineral is cubic, P4/m[IMG]f1.gif" ALT="Formula" BORDER="0"〉2/m, with unit-cell parameter refined using powder-diffraction data: a 3.7349(6) A, V 52.10(3) A3, Z = 1, Dcalc = 9.41 g/cm3. The average results of five and three electron-microprobe analyses on separate crystals gave Ni 57.88, Sn 40.17, sum 98.05 wt.% and Ni 59.24, Sn 41.00, sum 100.24 wt.%, corresponding to Ni2.98Sn1.02 on the basis of 4 apfu. The structure has been refined to an R index of 0.008% on the basis of 30 unique reflections. The structure of nisnite contains 12-coordinated Sn atoms (12 Ni) and 12-coordinated Ni atoms (8 Ni and 4 Sn). Among the three synthetic Ni3Sn phases known, nisnite corresponds to the ccp structure that has been synthesized at high pressure and high temperature.
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  • 3
    Publication Date: 2012-04-01
    Description: Eldragónite, with the simplified formula Cu6BiSe4(Se2), is a new mineral species discovered in a telethermal vein-type deposit with selenides at the El Dragón mine, Province of Quijarro, Department of Potosí, Bolivia. It forms inclusions in krut’aite, and is associated with clausthalite, klockmannite, umangite and tiemannite, as well as with watkinsonite, petrovicite and two unnamed phases in the system Cu–Pb–Hg–Bi–Se. The unique vein of eldragónite-bearing krut’aite is hosted within sandstones and shales of Devonian age. Eldragónite occurs in anhedral grains and polycrystalline aggregates attaining a size of up to 100 × 80 μm. Megascopically, the mineral has a brownish to light-maroon color, is opaque and lacks internal reflections. It has a metallic luster and a brownish black streak, is brittle with an uneven to conchoidal fracture, without observable cleavage. The VHN15 values range between 212 and 243 (mean 225) kg/mm2, corresponding to a Mohs hardness of ~3 ½. In plane-polarized light, eldragónite is distinctly bireflectant and pleochroic, from light grayish brown to cream; it is strongly anisotropic with rotation tints in shades of orange and blue-black. The reflectances (in air and oil, respectively) for the COM standard wavelengths are: 32.5–34.5, 17.7–19.7 (470 nm), 32.95–36.3, 18.0–21.4 (546 nm), 33.3–36.8, 18.3–21.6 (589 nm), 34.0–36.9, 19.1–21.7 (650 nm). Electron-microprobe analyses gave (mean of 24 analyses): Cu 35.9, Fe 1.25, Ni 0.35, Bi 20.3, Se 42.5, total 100.3 wt.%, corresponding to (Cu5.98Fe0.24Ni0.06)∑6.28Bi1.03Se5.70. The ideal formula is Cu6BiSe4(Se2), which requires Cu 35.84, Bi 19.64, Se 44.52 wt.%. Eldragónite has an orthorhombic cell, space group Pmcn, with a 4.0341(4), b 27.056(3), c 9.5559(9) Å, V 1043.0(3) Å3, and Z = 4. The calculated density is 6.76 g/cm3. The strongest X-ray powder-diffraction lines [d in Å (I) hkl] are: 6.547(58)031, 3.579(100)052, 3.253(48)141, 3.180(77)081, 3.165(56)013, 3.075(84)102, 3.065(75)151,112, 2.011(53)200, 1.920(76)154, 1.846(52)1103. The crystal structure was solved from single-crystal data, and was refined to R1= 0.026 on the basis of 1731 unique reflections. There are one Bi and six Cu positions. Among the six Se positions, two Se atoms form a Se2 pair [d(Se–Se) = 2.413 Å]; eldragónite is thus a mixed selenide–diselenide compound. The crystal structure is organized according to two slabs alternating along a. The thin slab with formula Cu6Se6 is a zigzag layer derived from the CaF2 archetype; the thick slab, Cu6Bi2Se6, is similar to that of wittichenite, Cu3BiS3. The Se2 pair is at the junction between these two slabs. This new mineral species is named after the location where it was discovered.
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  • 4
    Publication Date: 2012-04-01
    Description: Five specimens of “dognácskaite” from Dognecea (Caraş-Severin County, Banat, Romania), a poorly described substance, once considered a Cu–Bi sulfosalt, were studied by ore microscopy, SEM, EPMA, and XRPD methods. One of the specimens is probably that used for the original description by József Krenner. Every specimen proved to be a mixture with a similar mineral composition and texture. The main component of “dognácskaite” is bismuthinite rimmed by wittichenite (containing strings of native bismuth), the latter is in turn rimmed by copper sulfides (mainly djurleite with some covellite). Emplectite can also be found occasionally in the larger voids of bismuthinite. Magnetite (in some cases oxidized), chalcopyrite, bornite (replacing chalcopyrite) and rare sphalerite and tetradymite form inclusions in bismuthinite or in the rims surrounding it. Goethite, calcite, bismuth ochre and other unspecified fine-grained products of alteration are abundant in the voids. Data from earlier studies are easily explainable on the basis of this mineral assemblage, suggesting that every specimen of “dognácskaite” is a mixture of this kind. The samples may correspond to a (pyrite–) magnetite – chalcopyrite skarn ore replaced by a post-skarn hydrothermal bismuthinite ore, later affected by supergene copper enrichment then by oxidation processes. The exact locality of “dognácskaite” cannot be determined, but at least some of the specimens have been collected in the former Petri-Pauli (or Péter-Pál), now Petruşi Pavel mine on Mt. Danilii.
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  • 5
  • 6
    Publication Date: 2011-12-01
    Description: Törnroosite, ideally Pd11As2Te2, is a new mineral species discovered in a heavy-mineral concentrate from the Miessijoki River, Lemmenjoki area, Inari Commune, Finnish Lapland, Finland. It is cubic, space group Fd3¯m (#227), by analogy with isomertieite, a 12.3530(4) Å, V 1885.03 (1) Å3, Z = 8. The strongest six lines of the X-ray powder-diffraction pattern [d in Å (I) hkl] are: 2.182(100)440, 2.376(90)511, 333, 1.544(15)800, 1.862(13)622, 1.2606(13)844, and 1.608(11)731, 553. The associated minerals include sperrylite, Pt–Fe alloy, cooperite, braggite, native Os–Ir–Ru alloy, irarsite, laurite, isomertieite, mertieite II, native Pt, native gold–silver alloy, atokite, Pt–Cu alloy, Cu–Pt–Pd alloy, Cu–Pd–Pt–Au alloy, Pd–Au alloy, along with magnetite, ilmenite, chromite, hematite, columbite–tantalite, tapiolite, garnet, monazite, zircon, pyrite, rutile, uraninite–thorianite, galena, and a mineral of the wolframite series. Törnroosite is black, opaque with a metallic luster, with a silvery black streak. The mineral is isotropic with a yellowish white color in comparison with sperrylite. The reflectance values in air for the standard COM wavelengths are: 45.4 (470 nm), 51.0 (546 nm), 54.1 (589 nm) and 57.45% (650 nm). The calculated density is 11.205(1) g/cm3 (for the empirical formula and unit-cell parameter refined from powder data). The electron-microprobe analyses gave, on average, Pd 72.04, Pt 1.75, Sn 2.13, Sb 0.85, As 8.77, Te 13.15 and Bi 0.79, total 99.48 wt.%, which corresponds to (Pd10.85 Pt0.14)?10.99(As1.88Sb0.11)?1.99(Te1.65Sn0.29Bi0.06)?2.00, based on a total of 15 atoms per formula unit. The average micro-indentation hardness (VHN25) is 519 (n = 4), corresponding to a Mohs hardness of 5. The mineral is named after Professor Ragnar Törnroos, University of Helsinki, Finland.
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  • 7
    Publication Date: 2018
    Description: 〈div data-abstract-type="normal"〉 〈p〉This study presents a complete characterization of kenoplumbomicrolite, (Pb,□)〈span〉2〈/span〉Ta〈span〉2〈/span〉O〈span〉6〈/span〉[□,(OH),O], occurring in an amazonite pegmatite from Ploskaya Mountain, Western Keivy Massif, Kola Peninsula, Murmanskaja Oblast, Northern Region, Russia.〈/p〉 〈p〉Kenoplumbomicrolite occurs in yellowish brown octahedral, cuboctahedral and massive crystals, up to 20 cm, has a white streak, a greasy lustre and is translucent. The Mohs hardness is ~6. Attempts to measure density (7.310–7.832 g/cm〈span〉3〈/span〉) were affected by the ubiquitous presence of uraninite inclusions. Reflectance values were measured in air and immersed in oil. Kenoplumbocrolite is optically isotropic. The empirical formula is (Pb〈span〉1.30〈/span〉□〈span〉0.30〈/span〉Ca〈span〉0.29〈/span〉Na〈span〉0.08〈/span〉U〈span〉0.03〈/span〉)〈span〉Σ2.00〈/span〉(Ta〈span〉0.82〈/span〉Nb〈span〉0.62〈/span〉Si〈span〉0.23〈/span〉Sn〈span〉4+〈/span〉〈span〉0.15〈/span〉Ti〈span〉0.07〈/span〉Fe〈span〉3+〈/span〉〈span〉0.10〈/span〉Al〈span〉0.01〈/span〉)〈span〉Σ2.00〈/span〉O〈span〉6〈/span〉[□〈span〉0.52〈/span〉(OH)〈span〉0.25〈/span〉O〈span〉0.23〈/span〉]〈span〉Σ1.00〈/span〉 (from the crystal used for the structural study) and (Pb〈span〉1.33〈/span〉□〈span〉0.66〈/span〉Mn〈span〉0.01〈/span〉)〈span〉Σ2.00〈/span〉(Ta〈span〉0.87〈/span〉Nb〈span〉0.72〈/span〉Sn〈span〉4+〈/span〉〈span〉0.18〈/span〉Fe〈span〉3+〈/span〉〈span〉0.11〈/span〉W〈span〉0.08〈/span〉Ti〈span〉0.04〈/span〉)〈span〉Σ2.00〈/span〉O〈span〉6〈/span〉[□〈span〉0.80〈/span〉(OH)〈span〉0.10〈/span〉O〈span〉0.10〈/span〉]〈span〉Σ1.00〈/span〉 (average including additional fragments). The mineral is cubic, space group 〈span〉Fd〈/span〉〈span〉〈span〉〈img data-mimesubtype="gif" data-type="simple" src="http://static.cambridge.org/resource/id/urn:cambridge.org:id:binary:20181109112359083-0385:S0026461X18000075:S0026461X18000075_inline1.gif"〉 〈span data-mathjax-type="texmath"〉 〈/span〉 〈/span〉〈/span〉〈span〉m〈/span〉. The unit-cell parameters refined from powder X-ray diffraction data are 〈span〉a〈/span〉 = 10.575(2) Å and 〈span〉V〈/span〉 = 1182.6(8) Å〈span〉3〈/span〉, which are in accord with those obtained previously from a single crystal of 〈span〉a〈/span〉 = 10.571(1) Å, 〈span〉V〈/span〉 = 1181.3(2) Å〈span〉3〈/span〉 and 〈span〉Z〈/span〉 = 8. The mineral description and its name have been approved by the Commission on New Minerals, Nomenclature and Classification of the International Mineralogical Association (IMA2015-007a).〈/p〉 〈/div〉
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  • 8
    Publication Date: 2012-04-01
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  • 9
    Publication Date: 2020-04-29
    Description: Bowlesite is a new mineral discovered in the Merensky Reef of the Rustenburg Platinum Mine, Bushveld complex, South Africa. Bowlesite forms tiny grains (maximum dimension 20 μm). It is associated with sulfides including chalcopyrite, pyrrhotite and pentlandite, in contact with silicates including plagioclase, pyroxene- and minor serpentine-subgroup and amphibole-supergroup minerals. Bowlesite is brittle and has a metallic lustre. In plane-polarised light, bowlesite has a light bluish grey colour. It shows weak bireflectance, no pleochroism and has weak anisotropism. Internal reflections were not observed. Reflectance values of bowlesite in air (R1, R2 in %) are: 50.3–51.4 at 470 nm, 48.5–48.9 at 546 nm, 47.9–48.6 at 589 nm and 47.8–48.7 at 650 nm. Ten spot analyses of bowlesite give the average composition: Pt 56.85, Pd 0.02, Sn 34.03 and S 9.15, total 100.05 wt.%, corresponding to the empirical formula (Pt1.001Pd0.001)Σ1.002Sn0.997S1.001, based on 3 atoms per formula unit. The simplified formula is PtSnS. Due to the small size of bowlesite, the crystal structure was solved and refined from the powder X-ray-diffraction data of synthetic PtSnS. The calculated density is 10.06 g⋅cm–3. The mineral is orthorhombic, space group: Pca21 (#29) with a = 6.11511(10), b = 6.12383(10), c = 6.09667(11) Å, V = 228.31(1) Å3 and Z = 4. Bowlesite is isotypic with cobaltite, CoAsS. The origin of bowlesite is probably related to low-T exsolution of Pt–Sn phases from high-T sulfides crystallised from the sulfide melt. The mineral honours Dr. John Bowles (Manchester University, UK) for his contributions to ore mineralogy and mineral deposits related to mafic–ultramafic rocks.
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  • 10
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