The platinum-group element distribution in the Dumont Sill, Quebec. Implications for the formation of ni-sulfide mineralization

1990 ◽  
Vol 42 (1-4) ◽  
pp. 97-119 ◽  
Author(s):  
G. E. Br�gmann ◽  
A. J. Naldrett ◽  
J. M. Duke
Keyword(s):  
Platinum Group Element ◽  
Element Distribution ◽  
Group Element ◽  
Sulfide Mineralization ◽  
Platinum Group

Review of platinum-group element distribution and mineralogy in chromitite ores from southern Iran

2012 ◽  
Vol 48 ◽  
pp. 278-305 ◽  
Author(s):  
Mohammad Reza Jannessary ◽  
Frank Melcher ◽  
Jerzy Lodziak ◽  
Thomas C. Meisel
Keyword(s):  
Platinum Group Element ◽  
Element Distribution ◽  
Group Element ◽  
Southern Iran ◽  
Platinum Group

Platinum-Group Element Distribution in Some Ore Deposits: Results of EPMA and Micro-PIXE Analyses

2004 ◽  
Vol 147 (3) ◽  
Author(s):  
Fernando Gervilla ◽  
Louis J. Cabri ◽  
Kari Kojonen ◽  
Thomas Oberth�r ◽  
Thorolf W. Weiser ◽  
...  
Keyword(s):  
Platinum Group Element ◽  
Element Distribution ◽  
Ore Deposits ◽  
Group Element ◽  
Platinum Group

Multiple S Isotopes and S Isotope Heterogeneity at the East Eagle Ni-Cu-Platinum Group Element Deposit, Northern Michigan

2020 ◽  
Vol 115 (3) ◽  
pp. 527-541
Author(s):  
E.K. Benson ◽  
E.M. Ripley ◽  
C. Li ◽  
B.W. Underwood ◽  
R. Mahin
Keyword(s):  
Platinum Group Element ◽  
Group Element ◽  
Spatial Proximity ◽  
Small Scale ◽  
Sulfide Mineralization ◽  
Exchange Reactions ◽  
Wide Range ◽  
Platinum Group ◽  
Northern Michigan ◽  
S Isotope

Abstract The East Eagle Ni-Cu-platinum group element deposit is a conduit-type deposit located in northern Michigan, in close spatial proximity to the currently producing Eagle deposit. Massive and semimassive (net-textured) sulfide mineralization at East Eagle occurs approximately 800 m lower in the stratigraphic sequence than that at Eagle and only ~200 m above the contact between Proterozoic and Archean rocks. Although sulfide mineralogy and textural types are similar at the two occurrences, there are important differences in their S isotope systematics. Massive sulfide mineralization at East Eagle is characterized by a relatively narrow range of δ34S values from 1.5 to 3.2‰. Semimassive sulfides show a similar range from 2.1 to 3.8‰. In strong contrast to these values, those from disseminated sulfides that border the massive and semimassive mineralization define a much larger range from –4.3 to 22.8‰. The much more restricted range in δ34S values recorded in the massive and semimassive sulfide mineralization compared to that of the disseminated mineralization is thought to reflect isotopic exchange reactions in the conduit involving accumulated sulfide and pulses of magma containing S of mantle origin. The ∆33S values of all three major types of sulfide mineralization at East Eagle are near 0‰, with most values between –0.03 and 0.03‰. Unlike ∆33S values from semimassive sulfide mineralization at Eagle, the ∆33S values at East Eagle show no, or very limited, evidence for the involvement of S derived from Archean sedimentary rocks. The wide range in δ34S values recorded in the disseminated mineralization provides strong evidence that S from Proterozoic sedimentary host rocks was involved in the mineralization; in some cases, as much as 85% of the S may have been of external origin. In addition to the wide range in δ34S values, the disseminated mineralization is characterized by spatially heterogeneous δ34S values. Meter-scale S isotope variations, as well as variations in Pt and Pd tenor, are consistent with multiple inputs of magma, each characterized by distinct S isotope ratios. Heterogeneity of several per mill at the centimeter scale indicates that the degree of supercooling exceeded the S diffusivity, preserving small-scale S isotope variability inherited from the sedimentary country-rock source. Elongate, branching plagioclase grains in many of the gabbroic rocks that host the disseminated sulfide mineralization are consistent with a rapid second stage of cooling.

Supergene mobilization and redistribution of platinum-group elements in the Merensky Reef, eastern Bushveld Complex, South Africa

2021 ◽  
Vol 59 (6) ◽  
pp. 1381-1396
Author(s):  
Maximilian Korges ◽  
Malte Junge ◽  
Gregor Borg ◽  
Thomas Oberthür
Keyword(s):  
South Africa ◽  
Platinum Group Element ◽  
Bushveld Complex ◽  
Platinum Group Elements ◽  
Element Distribution ◽  
Group Element ◽  
Recovery Rates ◽  
Merensky Reef ◽  
Platinum Group Minerals ◽  
Platinum Group

ABSTRACT Near-surface supergene ores of the Merensky Reef in the Bushveld Complex, South Africa, contain economic grades of platinum-group elements, however, these are currently uneconomic due to low recovery rates. This is the first study that investigates the variation in platinum-group elements in pristine and supergene samples of the Merensky Reef from five drill cores from the eastern Bushveld. The samples from the Richmond and Twickenham farms show different degrees of weathering. The whole-rock platinum-group element distribution was studied by inductively coupled plasma-mass spectrometry and the platinum-group minerals were investigated by reflected-light microscopy, scanning electron microscopy, and electron microprobe analysis. In pristine (“fresh”) Merensky Reef samples, platinum-group elements occur mainly as discrete platinum-group minerals, such as platinum-group element-sulfides (cooperite–braggite) and laurite as well as subordinate platinum-group element-bismuthotellurides and platinum-group element-arsenides, and also in solid solution in sulfides (especially Pd in pentlandite). During weathering, Pd and S were removed, resulting in a platinum-group mineral mineralogy in the supergene Merensky Reef that mainly consists of relict platinum-group minerals, Pt-Fe alloys, and Pt-oxides/hydroxides. Additional proportions of platinum-group elements are hosted by Fe-hydroxides and secondary hydrosilicates (e.g., serpentine group minerals and chlorite). In supergene ores, only low recovery rates (ca. 40%) are achieved due to the polymodal and complex platinum-group element distribution. To achieve higher recovery rates for the platinum-group elements, hydrometallurgical or pyrometallurgical processing of the bulk ore would be required, which is not economically viable with existing technology.

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