(n) a green or yellow or brown mineral consisting of a hydrated silicate; it occurs as crystals in limestone and is used a gemstone, Syn. idocrase, vesuvian
n. (Min.) A mineral occurring in tetragonal crystals, and also massive, of a brown to green color, rarely sulphur yellow and blue. It is a silicate of alumina and lime with some iron magnesia, and is common at Vesuvius. Also called idocrase. [ 1913 Webster ]