Goryainovite, Ca2PO4Cl, is a new halophosphate, the chlorine analogue of 'spodiosite', Ca2PO4F. It is orthorhombic, Pbcm, a = 6.215(2), b = 7.011(2), c = 10.788(3) angstrom, V = 470.0(8) angstrom(3), Z = 4 (from powder X-ray diffraction data). The mineral is found in a magnetite-serpentine rock of the Stora Sahavaara iron ore deposit (67.408 degrees N 23.297 degrees E) where it forms small (up to 20 mu m in diameter) rounded inclusions in magnetite, in close association with hydroxylapatite-chlorapatite, pyrrhotite, pyrite, chalcopyrite, valleriite and thorianite. Goryainovite is a transparent, colourless mineral with a vitreous lustre and a white streak. Cleavage is not observed, and the fracture is conchoidal. The Mohs hardness is c. 4. In transmitted light, the mineral is colourless, biaxial (-), beta approximate to 1.66 (for lambda = 589 nm). D-calc = 2.98 g.cm(-3). The mean chemical composition specified with electron microprobe is (wt.%): P2O5 33.19, Cl 16.96, CaO 53.25, O = Cl -3.83, total 99.57. The e