Por"phy*ry (?), n.; pl. Porphyries (#). [F. porphyre, L. porphyrites, fr. Gr. like purple, fr. 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.

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

© Webster 1913.