Whats interesting is that when iron sulphide is found in nature, it forms minerals. The most basic one is troilite (which is pale brown). Whats cool is when it forms minerals, sometimes the minerals are missing some of the iron and it forms minerals like Pyrrhotite and Pyrite. Pyrite is shiny and golden (sometime called fools gold) https://en.wikipedia.org/wiki/Pyrite https://en.wikipedia.org/wiki/Troilite
Hope this helps – let me know if you want to know more!
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