Chemical composition: Be3Al, Si () lg; small amount of Na, Rb and Li may substitute for be; H., 0 and CO, may occur within rings.
(i) Form: Hexagonal prism or columnar aggregates.
(ii) Colour: Colourless, bluish-green, emerald-green, golden-yellow, pink, white.
(iii) Lustre: Vitreous.
(iv) Streak: White.
(v) Hardness: 7-8.
(vi) Cleavage: Indistinct.
(vii) Fracture: Conchoidal to uneven.
(viii) Specific gravity: 2.7 – 2.9.
(ix) Diaphaneity: Transparent to translucent.
Beryl is the major source of beryllium, which is made alloy with copper resulting in increase of hardness, tensile strength and fatigue resistance of copper. Emerald, transparent and emerald-green (pale green) and aquamarine, transparent pale blue varieties of beryl are used as gemstones.