Original paper

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

Zaccarini, Federica; Proenza, Joaquin A.; Rudashevsky, Nikolay S.; Cabri, Louis J.; Garuti, Giorgio; Rudashevsky, Vladimir N.; Melgarejo, Joan C.; Lewis, John F.; Longo, Francisco; Bakker, Ronald J.; Stanley, Chris J.

Abstract

Platinum group element (PGE) rich ophiolitic chromitites associated with the Loma Peguera harzburgitic mantle have been investigated for Platinum group minerals (PGM) using electric pulse disaggregation (EPD) and hydroseparation (HS) techniques. Combination of these two techniques allows for efficient concentration of the heavy minerals, including PGM. The PGM have been analyzed by electron microprobe, by Raman spectroscopy and investigated for their reflectivity. The majority of the discovered PGM, on the basis of their chemical composition and optical properties, potentially represent new mineral species, including Ru,Os,Ir,Fe compounds, Ir(Fe,Ni)3, Ir(Ni,Fe)3, (Ir,Pt)(Fe,Ni), Pt(Ni,Fe)3, (Ru,Pt)(Fe,Ni), (Fe,Ru,Ni,Os,Ir,Co)2S and Rh,Ni,As.One disadvantage of an investigation of concentrates is that some in situ textural information is lost. However, on the basis of their morphology and some attached associated minerals, the presence of oxygen, altered chromite, and serpentine, we can argue that most of the discovered PGM are secondary in origin, i.e. formed at low temperature during post magmatic processes.

Keywords

platinum group mineralschromititesophioliteloma pegueradominican republic