n.; pl. Porphyries [ F. porphyre, L. porphyrites, fr. Gr. &unr_; like purple, fr. &unr_; purple. See Purple. ] (Geol.) A term used somewhat loosely to designate a rock consisting of a fine-grained base (usually feldspathic) through which crystals, as of feldspar or quartz, are disseminated. There are red, purple, and green varieties, which are highly esteemed as marbles. [ 1913 Webster ]

Porphyry shell (Zool.), a handsome marine gastropod shell (Oliva porphyria), having a dark red or brown polished surface, marked with light spots, like porphyry. [ 1913 Webster ]