Pyrite, also called iron pyrite or fool's gold, is a naturally occurring iron disulfide mineral. The name comes from the Greek word pyr, “fire,” because pyrite emits sparks when struck by metal. Pyrite is called fool's gold; to the novice, its colour is deceptively similar to that of a gold nugget. It is great for improving your respiratory health and boosting your immune system. This crystal is also known as iron pyrite or fools gold. It is a naturally occurring iron disulfide mineral.