Kiddcreekite, a copper-tin-tungsten sulfide, is a new mineral species that occurs as irregular grains in a bornite-rich ore zone of the Kidd Creek Mine, Timmins, Ontario and in the Campbell orebody, Bisbee, Arizona. The mineral has the ideal formula Cu 6 SnWS 8 and is thus the tungsten analog of hemusite Cu 6 SnMoS 8 . Kiddcreekite is opaque and optically isotropic in reflected light. In reflected plane-polarized light, the Kidd Creek grains are pale gray-brown, and the Bisbee grains are pale gray. Some grains display a purplish tint. The refined unit-cell parameter is a 10.856(2) Aa, V = 1279.4 Aa 3 . With Z = 4, the calculated density for stoichiometric Cu 6 SnWS 8 is 4.88 g/cm 3 . The strongest five lines in the X-ray-powder pattern [d in Aa (I) (hkl)] are: 6.29(100)(111), 1.919(60)(440), 3.138(50)(222), 5.41(30)(200), 3.270(30)(311). Indexing indicates a cubic F-lattice with aspect F***. The Vickers microhardness of a Bisbee grain gave VHN 100 = 183.--Modified journal abstract.