porphyry (n.)

type of ornamental stone, late 14c., porfurie, from Old French porfire, from Italian porfiro and in some cases directly from Latin porphyrites, a purple semi-precious stone 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.