ădămantēus, a, um, adj. [adamas],
of hard steel , iron , etc., or hard as these : catenae, adamantine , Manil. 1, 921: nares (taurorum), Ov. M. 7, 104.
adamantēus adj. adamas, hard as steel, adamantine, not to be broken (poet.): nares, O. ...
An Elementary Latin Dictionary