Platinum-group elements (PGE) and their principal carriers in metal-rich black shales: an overview with a new data from Mo-Ni-PGE black shales (Zunyi region, Guizhou Province, south China)

Abstract

Lower Cambrian Mo-Ni sulfidic black shales from the Huangjiawan mine (Guizhou Province, south China) have anomalous platinum-group elements (PGE) concentrations (up to ˜1 ppm in total). In order to identify principal PGE carriers, we used heavy mineral separates which were produced by innovative hydroseparation techniques. Subsequent detailed mineralogical study using electron microprobe did not result in the identification of discrete platinum-group minerals. Pyrite (grainy, not framboidal), millerite and gersdorffite that were identified in our heavy concentrate were analyzed for PGE and Re. We found that they contain the following concentrations of PGE and Re: pyrite (up to 490 ppm Pt, 390 ppm Pd and 220 ppm Rh), millerite (up to 530 ppm Pt, 430 ppm Pd and 190 ppm Rh) and gersdorffite (up to 410 ppm Pt and 320 ppm Pd; no Rh detected). Rhenium was detected only in grainy pyrite (up to 1060 ppm). It was found that despite anomalous PGE concentrations, the Mo-Ni black shales do not contain any platinum-group minerals and that the PGE are bound to pyrite and Ni-sulfides (millerite and gersdorffite)

The hydrothermal Waterberg platinum deposit, Mookgophong (Naboomspruit), South Africa. Part 1: Geochemistry and ore mineralogy

“…Examples are (1) manganese nodules and crusts formed in the marine environment on the ocean floor (e.g. Balaram et al , 2006; Banakar et al , 2007); (2) Mo–Ni–PGE black shale ores of China (Mao et al , 2002; Pašava et al , 2013) thought to have formed from evaporating sea water; (3) secondary oxide ores produced by weathering of primary mineralization (e.g. Great Dyke; Locmelis et al , 2010; Oberthür et al , 2013); and (4) placers (e.g.…”

Distribution of “Invisible” Noble Metals between Pyrite and Arsenopyrite Exemplified by Minerals Coexisting in Orogenic Au Deposits of North-Eastern Russia

“…However, if we consider other mineral occurrences that do not have a direct connection with magmatism, the picture will be somewhat different. For example, for the mineralisation of Mo-Ni-PGE in black shales [5], the distribution coefficients of invisible forms of Pt and Pd between pyrite and gersdorffite (NiAsS), which is the Ni-analogue of arsenopyrite, on average amount to~0.9; that is, no significant fractionation of these elements in the sulpharsenide phase is detected. On the other hand, Kravtsova et al [21] suggested that the increased content of PGEs and Au are typical of arsenopyrites formed at the hydrothermal stage, at the deposit of metamorphogenic-hydrothermal genesis, as confirmed by the rather high content of the structural forms of Pt and Pd in arsenopyrite.…”

In search of the lost link: the fascinating platinum host rock of Chocó, Colombia

“…Among the deposits of particular interest are unconventional (amagmatic) enrichments in sedimentary rocks such as black shale (e.g. Pašava et al, 2013;Wilde et al, 2003) and in carbonaceous and calcareous metasedimentary rocks, all of which are Paleozoic and Precambrian (e.g. Sener et al, 2002;Wilde et al, 2003).…”