a genus of spars. The word is derived from κύβος, "a die;" and is given them from their being of the shape of a common die, or of a cubic figure. These bodies owe this shape to an admixture of lead, and there are only two known species of the genus.

1. A colourless crystalline one, with thin flakes, found in the lead mines of Yorkshire, and some other parts of the kingdom; and,

2. A milky white one with thicker crusts. This is found in the lead-mines of Derbyshire and Yorkshire, but is usually small, and is not found plentifully.