Adamant

Adamant in the Topics

(Heb. shamir), Ezek 3:9. The Greek word adamas means diamond. This stone is not referred to, but corundum or some kind of hard steel. It is an emblem of firmness in resisting adversaries of the truth (Zech 7:12), and of hard-heartedness against the truth (Jer 17:1).

From Easton’s Bible Dictionary (1897), by Matthew George Easton.