The mineral pyrite, or iron pyrite, is an iron sulfide with the formula FeS2. This mineral’s metallic luster and pale-to-normal, brass-yellow hue have earned it the nickname fool’s gold because of its resemblance to gold. The color has also led to the nicknames brass, brazzle and Brazil, primarily used to refer to pyrite found in coal.
Pyrite is used as an abundant inexpensive material in low cost photovoltaic solar panels. Synthetic iron sulfide is used with copper sulfide to create the photovoltaic material.