pyrite

Noun

pyrite (plural pyrites)

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, Chiao-min Hsieh, “Mining and Manufacturing”, in Christopher L. Salter, editor, Atlas of China, McGraw-Hill, Inc., →ISBN, →LCCN, →OCLC, →OL, page 100, column 1
   • China's 13 large foreign fertilizer plants ordered a few years ago are all scheduled to be in operation in a year or two.[…]China's biggest pyrite mine (openpit), being built in Yunfu, Kwangtung Province, was near completion.1978 November 9, K. P. Wang, “China's Mineral Economy”, in Chinese Economy Post-Mao: A Compendium of Papers, Washington, D.C.: Government Printing Office, →OCLC, page 387
2. (usually) Any metallic-looking sulphide, such as the above, which is the most common.
3. (solid state chemistry) (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.