A rare metallic element, of a silver white color, and low
   specific gravity (2.1), resembling magnesium. It never occurs naturally
   in the free state, but is always combined, usually with silica or
   alumina, or both; as in the minerals phenacite, chrysoberyl, beryl or
   emerald, euclase, and danalite. It was named from its oxide glucina,
   which was known long before the element was isolated. Symbol Gl. Atomic
   weight 9.1. Called also beryllium.