CHROMIAN SPINEL COMPOSITION AND THE PLATINUM-GROUP MINERALS OF THE PGE-RICH LOMA PEGUERA CHROMITITES, LOMA CARIBE PERIDOTITE, DOMINICAN REPUBLIC

2007 ◽  
Vol 45 (3) ◽  
pp. 631-648 ◽  
Author(s):  
J. A. Proenza ◽  
F. Zaccarini ◽  
J. F. Lewis ◽  
F. Longo ◽  
G. Garuti
Keyword(s):  
Dominican Republic ◽  
Chromian Spinel ◽  
Platinum Group Minerals ◽  
Spinel Composition ◽  
Platinum Group

The evolution of the ore-forming system in the low sulfide horizon of the Noril'sk 1 intrusion, Russia

2019 ◽  
Vol 83 (5) ◽  
pp. 673-694 ◽  
Author(s):  
Nadezhda D. Tolstykh ◽  
Liudmila M. Zhitova ◽  
Maria O. Shapovalova ◽  
Ivan F. Chayka
Keyword(s):  
Mafic Magma ◽  
Chromian Spinel ◽  
Reducing Conditions ◽  
Platinum Group Minerals ◽  
Sulfide Melt ◽  
Formation And Evolution ◽  
Fe Alloys ◽  
Platinum Group ◽  
Monoclinic Pyrrhotite ◽  
Increased Activity

AbstractWe present here new data on the low-sulfide mineralisation in the upper endocontact of the Noril'sk 1 intrusion. Twenty four mineral species of platinum-group elements and their solid solutions, as well as numerous unnamed phases, including an Sb analogue of vincentite, As and Sn analogues of mertieite-I and a Sn analogue of mertieite-II have been found. It is shown that the features of the mineral association: (1) the atypical trend of TiO2 and Fe2+ in chromian spinel; (2) the composition of the Pt–Fe alloys with a Fe/Fe + Pt range of 0.26–0.37 (logfO2 ≈ – (9–10); and (3) crystallisation of high-temperature sperrylite from silicate melt (at >800°C and logfS2 < –10.5), which is possible under fO2 of FMQ to FMQ-2 in mafic magma, are due to the reducing conditions of their formation and evolution. Droplet-like inclusions of silicate-oxide minerals in сhromian spinels and sulfides in platinum-group minerals are interpreted to be trapped droplets of co-existing sulfide melt. The captured sulfide melt has evolved in the direction of increasing the fugacity of sulfur: troilite + pentlandite (Fe>Ni) – in sperrylite (paragenesis I) to monoclinic pyrrhotite + pentlandite (Ni≈Fe) + chalcopyrite – in Pt–Fe alloys (paragenesis II). Paragenesis from the sulfide aggregates in the silicate matrix are more fractionated: pyrrhotite + pyrrhotite (Ni>Fe) + chalcopyrite (III) and pyrite + pentlandite (Ni>>Fe) + millerite (IV). Pd arsenides and antimonides crystallised later than sperrylite and isoferroplatinum, as a result of the evolution of a sulfide melt with an increased activity of the element ligands (Te, Sn, Sb and As).

Platinum group minerals (PGM) in the Falcondo Ni-laterite deposit, Loma Caribe peridotite (Dominican Republic)

2014 ◽  
Vol 50 (1) ◽  
pp. 105-123 ◽  
Author(s):  
Thomas Aiglsperger ◽  
Joaquin A. Proenza ◽  
Federica Zaccarini ◽  
John F. Lewis ◽  
Giorgio Garuti ◽  
...  
Keyword(s):  
Dominican Republic ◽  
Platinum Group Minerals ◽  
Platinum Group

CHROMIAN SPINEL COMPOSITION AND PLATINUM-GROUP ELEMENT MINERALOGY OF CHROMITITES FROM THE MILIA AREA, PINDOS OPHIOLITE COMPLEX, GREECE

2009 ◽  
Vol 47 (5) ◽  
pp. 1037-1056 ◽  
Author(s):  
A. Kapsiotis ◽  
T. A. Grammatikopoulos ◽  
B. Tsikouras ◽  
K. Hatzipanagiotou ◽  
F. Zaccarini ◽  
...  
Keyword(s):  
Platinum Group Element ◽  
Group Element ◽  
Chromian Spinel ◽  
Ophiolite Complex ◽  
Spinel Composition ◽  
Platinum Group

Ophiolite-related associations of platinum-group minerals at Rudnaya, western Sayans and Miass, southern Urals, Russia

2018 ◽  
Vol 82 (3) ◽  
pp. 515-530 ◽  
Author(s):  
Andrei Y. Barkov ◽  
Nadezhda D. Tolstykh ◽  
Gennadiy I. Shvedov ◽  
Robert F. Martin
Keyword(s):  
Southern Urals ◽  
Chromian Spinel ◽  
Type Alloy ◽  
Chelyabinsk Oblast ◽  
The Southern Urals ◽  
Platinum Group Minerals ◽  
Pge Mineralization ◽  
Fe Alloys ◽  
Platinum Group ◽  
Western Sayan

ABSTRACTWe describe similar assemblages of minerals found in two placers in Russia, both probably derived from an ophiolitic source. The first is located along the River Rudnaya in the western Sayan province, Krasnoyarskiy kray, and the second pertains to the Miass placer zone, Chelyabinsk oblast, in the southern Urals. The platinum-group element (PGE) mineralization in both cases is mostly (at least 80%) represented by alloy minerals in the system Ru–Os–Ir, in the order of occurrence osmium, ruthenium and iridium. The remainder consists of Pt–Fe alloys and species of PGE sulfides, arsenides, sulfarsenides, etc. The associated olivine and amphiboles are supermagnesian, and the chromian spinel has a high Cr# value. The observed enrichment in Ru, typical of an ophiolitic source, may be due to high-temperature hydrothermal equilibration and mobilization in the ophiolite, as is the enrichment in Mg and Cr. Low-temperature replacement of the alloys led to the development of laurite, sulfoarsenides and arsenides. Some placer grains in both suites reveal unusual phases of sulfo-arsenoantimonides of Ir–Rh, e.g. the unnamed species (Rh,Ir)SbS and (Cu,Ni)1+x(Ir,Rh)1–xSb, wherex= 0.2, and rhodian tolovkite, (Ir,Rh)SbS. Two series of natural solid-solutions appear to occur in the tolovkite-type phases. Among the oddities in the Rudnaya suite are globules of micrometric PGE sulfides, crystallites of platinum-group minerals, amphibole, and chalcopyrite bearing skeletal micrometric monosulfide-like compounds (Cu,Pt,Rh)S and (Pd,Cu)S1–x. Pockets of fluxed evolved melt seem to have persisted well below the solidus of the host Pt3Fe-type alloy.

scholarly journals Fibrous Platinum-Group Minerals in “Floating Chromitites” from the Loma Larga Ni-Laterite Deposit, Dominican Republic

Minerals ◽  
2016 ◽  
Vol 6 (4) ◽  
pp. 126 ◽  
Author(s):  
Thomas Aiglsperger ◽  
Joaquín Proenza ◽  
Francisco Longo ◽  
Mercè Font-Bardia ◽  
Salvador Galí ◽  
...  
Keyword(s):  
Dominican Republic ◽  
Platinum Group Minerals ◽  
Platinum Group

The Loma Peguera ophiolitic chromitite (Central Dominican Republic): a source of new platinum group minerals (PGM) species

2009 ◽  
Vol 185 (3) ◽  
pp. 335-349 ◽  
Author(s):  
Federica Zaccarini ◽  
Joaquin A. Proenza ◽  
Nikolay S. Rudashevsky ◽  
Louis J. Cabri ◽  
Giorgio Garuti ◽  
...  
Keyword(s):  
Dominican Republic ◽  
Platinum Group Minerals ◽  
Platinum Group

scholarly journals Tamuraite, Ir5Fe10S16, a New Species of Platinum-Group Mineral from the Sisim Placer Zone, Eastern Sayans, Russia

Minerals ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 545
Author(s):  
Andrei Y. Barkov ◽  
Nadezhda D. Tolstykh ◽  
Robert F. Martin ◽  
Andrew M. McDonald
Keyword(s):  
National Laboratory ◽  
X Ray Diffraction ◽  
Calculated Density ◽  
Cell Parameters ◽  
Reflected Light ◽  
Platinum Group Minerals ◽  
Platinum Group ◽  
Probable Space ◽  
Layered Complex ◽  
Residual Melt

Tamuraite, ideally Ir5Fe10S16, occurs as discrete phases (≤20 μm) in composite inclusions hosted by grains of osmium (≤0.5 mm across) rich in Ir, in association with other platinum-group minerals in the River Ko deposit of the Sisim Placer Zone, southern Krasnoyarskiy Kray, Russia. In droplet-like inclusions, tamuraite is typically intergrown with Rh-rich pentlandite and Ir-bearing members of the laurite–erlichmanite series (up to ~20 mol.% “IrS2”). Tamuraite is gray to brownish gray in reflected light. It is opaque, with a metallic luster. Its bireflectance is very weak to absent. It is nonpleochroic to slightly pleochroic (grayish to light brown tints). It appears to be very weakly anisotropic. The calculated density is 6.30 g·cm−3. The results of six WDS analyses are Ir 29.30 (27.75–30.68), Rh 9.57 (8.46–10.71), Pt 1.85 (1.43–2.10), Ru 0.05 (0.02–0.07), Os 0.06 (0.03–0.13), Fe 13.09 (12.38–13.74), Ni 12.18 (11.78–13.12), Cu 6.30 (6.06–6.56), Co 0.06 (0.04–0.07), S 27.23 (26.14–27.89), for a total of 99.69 wt %. This composition corresponds to (Ir2.87Rh1.75Pt0.18Ru0.01Os0.01)Σ4.82(Fe4.41Ni3.90Cu1.87Co0.02)Σ10.20S15.98, calculated based on a total of 31 atoms per formula unit. The general formula is (Ir,Rh)5(Fe,Ni,Cu)10S16. Results of synchrotron micro-Laue diffraction studies indicate that tamuraite is trigonal. Its probable space group is R–3m (#166), and the unit-cell parameters are a = 7.073(1) Å, c = 34.277(8) Å, V = 1485(1) Å3, and Z = 3. The c:a ratio is 4.8462. The strongest eight peaks in the X-ray diffraction pattern [d in Å(hkl)(I)] are: 3.0106(26)(100), 1.7699(40)(71), 1.7583(2016)(65), 2.7994(205)(56), 2.9963(1010)(50), 5.7740(10)(45), 3.0534(20)(43) and 2.4948(208)(38). The crystal structure is derivative of pentlandite and related to that of oberthürite and torryweiserite. Tamuraite crystallized from a residual melt enriched in S, Fe, Ni, Cu, and Rh; these elements were incompatible in the Os–Ir alloy that nucleated in lode zones of chromitites in the Lysanskiy layered complex, Eastern Sayans, Russia. The name honors Nobumichi Tamura, senior scientist at the Advanced Light Source of the Lawrence Berkeley National Laboratory, Berkeley, California.

DETRITAL PLATINUM-GROUP MINERALS IN RIVERS DRAINING THE EASTERN BUSHVELD COMPLEX, SOUTH AFRICA

2004 ◽  
Vol 42 (2) ◽  
pp. 563-582 ◽  
Author(s):  
T. Oberthur ◽  
F. Melcher ◽  
L. Gast ◽  
C. Wohrl ◽  
J. Lodziak
Keyword(s):  
South Africa ◽  
Bushveld Complex ◽  
Platinum Group Minerals ◽  
Platinum Group
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