Kusachiite, CuBi204, has been found in a calcite vein cutting gehlenite-spurrite skarns at Fuka, Okayama Prefecture. It is associated with calcite, henmilite, sillenite, bakerite, tenolite, bultfonteinite, apophyllite, cuspidine and thaumasite. Kusachiite occurs as prismatic crystals or globular aggregates of platy crystals. It is black, opaque with a metallic lustre. Kusachiite is tetragonal with space group P4/ncc, a = 8.511 (2) (17)(200), 2.913 (16)(002), 2.404 (13)(202), 1.728 (12)(213), and 1.652 (9)(332). The Mohs hardness is 4.5, and the density is 8.5(3) g/cm 3 (meas.) and 8.64 g/cm 3 (calc.). Cleavage is perfect on { 110}. Six electron probe analyses gave the following mean values CuO 13.91, Bi203 86.00 and total 99.91 in wt.%. The empirical formula calculated on the basis of O = 4 is Cu0.96oBi2.02704 with the simplified formula CuBi204.