BARTRA PRODUCT carefully selects its products to try to satisfy our customers. The pyrite stones shown are found in a wide variety of geological formations, naturally formed; typical of Huanzalá - Ancash - Peru, a mine recognized as one of the best and most prolific in the world. Pyrite, a crystallized mineral of the sulfide group (iron sulfide - FeS2), which gives it the name Iron Pyrite; The metallic luster of pyrite is due to its ability to reflect light uniformly in all directions; due to its dense atomic structure and regular arrangement of atoms in the crystal lattice. This metallic luster is what makes pyrite resemble gold; distinguishing it from chalcopyrite (which contains copper, iron, and sulfur and has less luster).