Lewis Short
(adjective) : porphyrētĭcus, a, um, πορφύρα
* Purple-red, porphyretic: marmor,Suet. Ner. 50: saxa,Lampr. Elag. 24: porticus,Vop. Prob. 2: columnae, Capitol. in Anton. Pio, 11: tabulae,Ambros. Ep. 53, 4.
Charlton T. Lewis, Charles Short, A Latin Dictionary