Pyrite and Pyrites

Pyrite noun - A common mineral (iron disulfide) that has a pale yellow color.

Pyrites is a synonym for pyrite. In some cases you can use "Pyrites" instead a noun "Pyrite".

Pyrites noun - Any of various metallic-looking sulfides (of which pyrite is the commonest).

Pyrite is a synonym for pyrites. You can use "Pyrite" instead a noun "Pyrites".