A dark-grey, almost black, copper bearing mineral, somewhat resembling Redruthite in general appearance, but of a duller lustre and considerably harder; the hardness being between 5 and 6. In parts a bronze tint and lustre is apparent. The specimen exhibits neither crystals nor crystalline structure, it breaks with a well marked couchoidal fracture. Lustre somewhat resinous; streak shining.

Heated in a glass tube it gives off water, having a strongly marked acid reaction, from the sulphurous acid which is evolved. Before the blowpipe it does not fuse, colours the flame green, and acquires a dull black colour. Treated with strong boiling nitric acid it is rapidly acted upon, a bronze coloured residue being left, the residue when examined under the microscope presents a honey-combed appearance; the walls of the irregular cellular cavities are pale-brown and translucent and apparently composed of quartz; when the powdered mineral is boiled with nitric acid, a white residue of silica is left.