 Beryllium is found in over 100 minerals , but most are uncommon to rare . The more common beryllium containing minerals include : bertrandite ( Be4Si2O7 ( OH ) 2 ) , beryl ( Al2Be3Si6O18 ) , chrysoberyl ( Al2BeO4 ) and phenakite ( Be2SiO4 ) . Precious forms of beryl are aquamarine , red beryl and emerald . The green color in gem @-@ quality forms of beryl comes from varying amounts of chromium ( about 2 % for emerald ) . 
