Godlevskite Ni9S8 from Dobromirtsi, Central Rhodopes, Bulgaria: First report for the country and genetic implications.

Abstract

Godlevskite Ni9S8 is recorded for the first time in Bulgaria. The find comes from chromitites in serpentinized ultramafics (dunites, peridotites), near the village of Dobromirtsi, Central Rhodopes. The postmagmatic assemblage of the chromitites comprises pentlandite, godlevskite, heazlewoodite, maucherite, orcelite, chalcopyrite and gersdorffite (in the order of decreasing abundance). The magmatic assemblage (in unaltered chromites) also includes pentlandite and less heazlewoodite and millerite as well as PGM – laurite, scarce OsIr alloys and Ir-sulpharsenides. The generalized formula of the recorded mineral, derived from microprobe analyses is: Ni8.82 Fe0.14 S8.04. Observed textural and structural specifics of the mineral are interpreted as evidences for a solid state re-equilibration from high-temperature MSS (Monosulfide Solid Solution), stable in the 577 – 436ºC temperature range, followed by slow annealing below 379ºC, well corresponding to the temperature conditions of the regional metamorphic events in the area.