porphyry (n.)

type of very hard stone made of crystals embedded in a homogeneous base, late 14c., porfurie, from Old French porfire, pourfire, from Italian porfiro and in some cases directly from Latin porphyrites, name given by the Romans to a purple stone used extensively for ornamental purposes and quarried near the Red Sea in Egypt, from Greek porphyrites (lithos) "the purple (stone)," from porphyra (n.) "purple, purple dye" (see purple). Spelling Latinized mid-15c. Now used generally for a type of igneous rock without regard to color. Porphyrios was an ancient proper name.