Subsulphuret of Copper,—Vitreous Copper Ore

Tabs. 359 and 360 have already shown some modifications of this species of Sulphuret of Copper. The present specimen exhibits single or grouped hexaëdral prisms often heaped in a curious order, generally very distinct from the Pyrites on which they lie, as if scattered over it by chance. The sides of the prisms are more or less broad, corresponding with an irregularity in their aggregating; nevertheless the angles measure constantly 120° or 60°. They are relieved by the line contrast of colours in the upper figure among beautiful blistered Copper Pyrites; see tab. 432: in the lower specimen they are upon a piece of Quartzose Oxide of Iron;—both are from Cornwall.