Entry 1 sense Webster, 1913 Fayalite /(fā"al*īt)/ · Fay·al·ite · IPA 01 n. A black, greenish, or brownish mineral of the chrysolite group. It is a silicate of iron. 1. A black, greenish, or brownish mineral of the chrysolite group. It is a silicate of iron.(Min.)