pyrite

noun3

1. •
   The common mineral iron disulfide (FeS₂), of a pale brass-yellow color and brilliant metallic luster, crystallizing in the isometric system.

   • The pyrite output in 1961 was 1.2 million tons, derived mainly from the Hsiang Shan mine in Anhwei and the Ying-te mine in Kwangtung. — 1973
2. •
   Any metallic-looking sulphide, such as the above, which is the most common.
3. •
   (usually as a plural: pyrites) Any metal dichalcogenide that is isostructural to the common mineral.

   • Copper diselenide can occur both as a marcasite and a pyrite.