Naturally occurring, gold-coloured iron disulfide mineral. Pyrite has frequently fooled prospectors into thinking they had discovered gold. Pure pyrite (FeS) contains 47% iron and 53% sulfur, by weight. Pyrite is used commercially as a source of sulfur, particularly for the production of sulfuric acid. Because there are much better sources of iron, it is not generally used as an iron ore. For many years Spain was the largest producer; other countries include Japan, the U.S., Canada, Italy, Norway, Portugal, and Slovakia.