A hexagonal mineral, Be₃Al₂Si₆O₁₈; green, blue-green, and other pale tints; in granite pegmatites, mica schists, and an accessory mineral in felsic igneous rocks; the chief source of beryllium. Transparent and colored gem varieties include emerald, aquamarine, morganite, heliodor, golden beryl, bixbite, and vorobievite.