Tarkianite, a new mineral species of ideal composition (Cu,Fe)(Re,Mo) 4 S 8 , was recently discovered in sulfide concentrate from the Hitura Ni-Cu-PGE mine, Nivala, western central Finland. It is associated with pyrrhotite, pentlandite, valleriite, chalcopyrite, cubanite, mackinawite, chromite, and the PGE minerals sperrylite, michenerite, irarsite, froodite and hollingworthite. It is black, opaque with a metallic luster, a black streak, and is brittle with an irregular fracture. VHN 15 is in the range 537-584, which corresponds to a Mohs hardness of 5½ to 6. Under reflected plane-polarized light, the mineral is light brown-gray and isotropic. The CIE color values (illuminant C) are: x 0.314 (air), 0.315 (oil); y 0.321 (air), 0.323 (oil) Y: 38.9 (air), 21.7 (oil); d: 575 (air), 573 (oil); P e %: 2.1 (air), 3.2 (oil). The measured values of reflectance in air and oil for a single grain, respectively, are 38.02, 20.91 (470 nm), 37.87, 21.76 (546 nm), 39.18, 21.84 (589 nm), 39.30, 22.12 (650 nm) and values for 400-700 nm are tabulated. Tarkianite is cubic, F43m (by analogy with the synthetic equivalent), with unit-cell parameter refined from powder data: a 9.563(1) Å, V 874.5(1) Å 3 , Z = 4. plex is 1877 ± 2 Ma, determined on zircon from a crosscutting dyke of granitic pegmatite. The ore (Häkli et al. 1976) consists of 1) fine-grained sulfides disseminated in the serpentinite core, 2) medium-grained sulfides disseminated in the serpentinite and amphibole-dominant rock, and 3) high-grade interstitial disseminated sulfides and massive accumulations in an amphibole-dominant rock at the contact zones. In the core of the intrusive body, the main sulfides are pentlandite, mackinawite and valleriite. In the marginal zones, the main ore lodes consist of dense disseminations and net-textured primary intergrowths of pyrrhotite, pentlandite and mackinawite with secondary films of magnetite along cleavage planes of the sulfides. Chalcopyrite and graphite are common, and less common ore minerals include cobaltite, maucherite, nickeline, parkerite, native gold, Au-Ag alloy, native bismuth, pilsenite, tellurobismuthite, galena, altaite, clausthalite, ilmenite, chromite, cassiterite, monazite and uraninite. Tarkianite occurs with the primary sulfides and PGM. The concentrates were investigated for a detailed PGM study, as a follow-up to a previous study by Häkli et al. (1976). This earlier study showed that sperrylite is the only Ptbearing mineral, and that the Pd-bearing minerals include michenerite, froodite, Pd-bearing irarsite and an undefined Pd-bearing Bi-Ni telluride resembling melonite. Iridarsenite, irarsite and hollingworthite were reported as Ir-and Rh-bearing minerals.