pyrite

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.

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.

Any metallic-looking sulphide, such as the above, which is the most common.

(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.