chrysoberyl

1. (mineralogy) A vitreous mineral, often pale green, a mixed oxide of aluminium and beryllium with the chemical formula BeAl₂O₄, used as a gemstone.Examples: "Although there are dozens of different types of gems, among the best known and most important are diamond, ruby and sapphire, emerald and other gem forms of the mineral beryl, chrysoberyl, tanzanite, tsavorite, topaz and jade."countableuncountable