Occurrence of new phosphides and sulfide of Ni, Co, V, and Mo from chromitite of the Othrys ophiolite complex (Central Greece)

Unnamed phosphides of Ni, Co, V, Mo, and one V-sulfide were found in a chromitite of the Agios Stefanos mine (Othrys ophiolite, Central Greece). Most of the phosphides have a stoichiometry similar to allabogdanite or barringerite but show significant proportions of Co, V, and Mo. The minerals could correspond to a Ni-allabogdanite or Nibarringerite, and to a V-allabogdanite or V-barringerite. More complex stoichiometries are observed when Mo is the dominant metal, and thus it leads to a potentially new (Mo,V,Fe)3(Ni,Co)2P mineral. The sulfide corresponds to the ideal formula VS. All the grains vary in size between 5 and 80 μm, and show distinctive reflectance and optical properties. In contrast, Raman spectra are not significantly distinctive. The rare minerals occur intergrown with brecciated chromite, awaruite, and various sulfides produced by alteration of chromitite under reducing conditions. Interpretation of their origin is still speculative embracing a number of possible processes: i) high-temperature reaction of the chromitites with reducing fluids, at mantle depth, ii) low-temperature alteration during serpentinization, iii) post-orogenic, surface lightning strike, or iv) meteorite impact. The minerals described in this work potentially represent new mineral species that are still under study for a complete crystallographic characterization, as required for the acceptance by the IMA Commission on New Minerals, Nomenclature and Classification.