New occurrences of anduoite, (Ru,Os)As-2, from chromite deposits of Ukraine and Albania

Two new occurrences of anduoite, (Ru,Os)As-2, a rare platinum-group mineral (PGM), are reported from chromitites, one from the Kapitanov deposit, Ukra inian Shield, Ukraine, and the other from the Maja e Sukes deposit, Tropoja ophiolitic massif, Albania. At Kapitanov, anduoite occurs as discrete, hom ogeneous, euhedral crystals (6-9 and 1-2 mum) enclosed in two chromian spin el grains devoid of fractures. At Maja e Sukes, one crystal of anduoite (3 mum in diameter) belongs to a complex polyphase assemblage of PGM comprisin g sperrylite, hollingworthite and an unnamed sulfarsenide of Rh, Ir, Pd and Ni. The chemical composition of anduoite is comparable in both deposits: ( Ru0.79-0.80Os0.10-0.11Ir0-0.03Rh0.03-0.04Pt0-0.01Pd0.01-0.02Ni0-0.04)(Sigma 0.98-0.01)(As1.98-2.01S0.01-0.02)(Sigma1.99-2.03) These examples of anduoit e have a lower content of Ru than that described from the type locality in Tibet. A magmatic origin is proposed.