Pyrite

Pyrite has a shiny golden-yellow color and a metallic luster. Its name comes from the Greek word pyr, meaning "a gemstone that strikes fire," due to the sparks produced when pyrite strikes iron. While pyrite has a history of being mistaken for gold, it is differentiated by pyrite's lighter, tougher, broken-faced grains. You may hear pyrite called by its nickname "fool's gold." Marcasite is a polymorph of pyrite. It has the same chemistry, but a different crystal structure. In the jewelry trade, the names pyrite and marcasite are often used interchangeably.