Webster's Revised Unabridged Dictionary · 1913

Pyrite

Pyrite , noun

[Compare French pyrite. See Pyrites.]

(Mineralogy) A common mineral of a pale brass-yellow color and brilliant metallic luster, crystallizing in the isometric system; iron pyrites; iron disulphide.
Hence sable coal his massy couch extends, And stars of gold the sparkling pyrite blends. — E. Darwin