σῐδήρ-εος · sidēr-eos — LSJ
made of iron or steel, ἄξων Il. 5.723; σιδηρείη κορύνη 7.141; πύλαι 8.15; ὑποκρητηρίδιον Hdt. 1.25; σκύταλον Theoc. 17.31; χεὶρ σ. grappling-iron, Th. 4.25, 7.62: also σ. ὀρυμαγδός, i.e. the clang of arms, Il. 17.424; σ. οὐρανός the iron sky, the firmament, which the ancients held to be of metal, Od. 15.329 (cf. χάλκεος) ; σ. γένος, of the Iron age, Hes. Op. 176.
metaph., ἦ γὰρ σοί γε σ. ἐν φρεσὶ θυμός a soul of iron, i.e. hard, stubborn as iron, Il. 22.357, cf. Od. 23.172; οὐδέ μοι . . θυμὸς ἐνὶ στήθεσσι σ., ἀλλʼ ἐλεήμων 5.191; οὐδʼ εἴ οἱ κραδίη γε σ. ἔνδοθεν ἦεν 4.293; σιδήρειόν νύ τοι ἦτορ Il. 24.205, 521; ἦ ῥά νυ σοί γε σ. πάντα τέτυκται thou art iron all! Od. 12.280; πυρὸς μένος . . σ. the iron force of fire, Il. 23.177; of Heracles, the iron-sided, Simon. 8; of men, Ar. Ach. 491; σὰρξ σ. Theoc. 22.47; ὦ σιδήρεοι O ye ironhearted! Aeschin. 3.166; εἰ
σιδάρεοι, οἱ, Byzantine iron coins, always used in Dor. form, even at Athens, Ar. Nu. 249, Pl.Com. 96, Stratt. 36.