Beryl
BERYL ber’ əl, a mineral which is commonly pale green, but may be deep green, blue yellow, brown pink or white. Certain varieties have long been used as gem stones (Rev 21:20), emerald (q.v.) being emerald-green to deep green, aquamarine, pale blue-green, heliodor yellow and morganite pink. The oriental emerald of jewelry is emerald-colored sapphire (q.v.) Beryl is applied to the coarse kinds which on account of their opacity are unfit for jewelry. It is a beryllium aluminum silicate. Crystals are common, often of large size (up to 5 millimeters in length and 1 millimeter in diameter) and are of prismatic habit, being made up of the hexagonal prism, terminated by the basal plane, sometimes with hexagonal pyramid forms and often striated vertically. In antiquity the term chrysolite (q.v.), a transparent yellow or green gem stone, was applied to various gems, including beryl, while chrysoprase (q.v.), another ancient name for a golden-green precious stone, is now generally believed to have been a variety of beryl.
Beryl is most commonly found in granitic rocks, either lining cavities in granite, or in pegmatite veins. The gem varieties come mainly from Colombia where the beryl occurs in a bituminous limestone, but common beryl is widely distributed in India, Australia, the U.S.A. and other places.
Bibliography
H. H. Read, Rutley’s Elements of Mineralogy, 26th ed. (1970), 292, 293.