Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
† porphyrētĭcus, a, um, adj. [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.