King James Bible Dictionary

(Heb. shamir), Ezekiel 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 (Zechariah 7:12), and of hard-heartedness against the truth (Jeremiah 17:1).

A flint.
Ezekiel 3:9; Zech 7:12
Diamond

the translation of the Hebrew word Shamir in (Ezekiel 3:9) and Zechariah 7:12 In (Jeremiah 17:1) it is translated "diamond." In these three passages the word is the representative of some stone of excessive hardness, and is used metaphorically. It is very probable that by Shamir is intended emery , a variety of corundum , a mineral inferior, only to the diamond in hardness.

AD'AMANT, noun [ Gr.; Latin adamas; a word of Celtic origin.]

A very hard or impenetrable stone; a name given to the diamond and other substances of extreme hardness. The name has often been given to the load stone; but in modern mineralogy, it has no technical signification.

ADAMANTE'AN, adjective Hard as adamant.

ADAMANT'INE, adjective Made of adamant; having the qualities of adamant; that cannot be broken, dissolved, or penetrated, as adamantine bonds, or chains.

Adamantine Spar, a genus of earths, of three varieties. The color of the first is gray, with shades of brown or green; the form when regular, a hexangular prism, two sides large and four small, without a pyramid; its surface striated, and with a thin covering of white mica, interspersed with particles of red felspar; its fracture, foliaceous and sparry. The second variety is whiter, and the texture more foliaceous. The third variety is of a reddish brown color. This stone is very hard, and of difficult fusion.

A variety of corrundum.