Eū’clāse, n.

n. [Fr. euclase, Ger. euklas, from Gr. εὖ, well, and κλάειν, to break, easily broken.] (Min.) A brittle gem of the beryl family, consisting of silica, alumina, and glucina. It occurs in light, green, transparent crystals, affording a brilliant diagonal cleavage, and is obtained from the topaz localities in Brazil. Dana.