ἰός · ios — LSJ
rust, verdigris, patina
rust on iron, or verdigris on copper and bronze, Sapph. 141 (dub.), Thgn. 451, Pl. R. 609a, Ti. 59c, Theoc. 16.17; ἰ. σιδήρου Dsc. 5.80; ἰ. χαλκοῦ Hp. Mul. 1.75, Dsc. 5.79, Gal. 12.218; patina on bronze statues, ὅπως καθαρὸς ἰοῦ ἔσται ὁ ἀνδριάς SIG 284.15 (Chios, iv B.C.), cf. Plu. Pyth. 2.395b. (Perh. identical with ἰός B.)