n.
Mineral composed of beryllium aluminum silicate, Be 3 Al 2 (SiO 3 ) 6 , a commercial source of beryllium .
Several varieties are valued as gemstones: aquamarine (pale blue-green); emerald (deep green); heliodor (golden yellow); and morganite (pink). Before 1925 beryl was used only as a gemstone, but since then many important uses have been found for beryllium (e.g., in nuclear reactors, space vehicles, and X-ray tubes). No large deposits have been found, and most production is a by-product of the mining of feldspar and mica. Brazil is a major producer; others include Zimbabwe, South Africa, Namibia, and the U.S.