What is the meaning of Pyrite?

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

(usually as a plural: pyrites) 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.

the metallic mineral pyrite

Source: wiktionary.org