4.1" Chalcopyrite, Pyrite, Sphalerite and Galena Association - Peru

About Pyrite

Pyrite, or iron pyrite, is best known as “Fool’s Gold” thanks to its bright metallic luster and pale brass-yellow color, which can easily be mistaken for real gold in poor lighting. With the chemical formula FeS₂, pyrite is the most abundant sulfide mineral on Earth and forms in an impressive range of geological environments.

One of pyrite’s defining features is its remarkable diversity of crystal habits—over 20 documented forms—making it one of the most morphologically varied minerals known. It commonly occurs as sharp cubes, octahedra, and pyritohedra, but also forms pentagonal dodecahedra, penetration twins, striated combinations, and complex modified forms prized by collectors. It can develop as massive veins, nodules, botryoidal growths, and fine druzy coatings that shimmer brilliantly under light. Whether glittering in tiny clusters or displayed as perfectly geometric crystals, pyrite showcases an extraordinary range of natural architecture and visual appeal.

Sphalerite is a part of the sulfide group and typically exhibits a grey/black appearance due to high concentrations of impurities. In its purest state, sphalerite's chemical composition is ZnS, and can display a gemmy transparent light tan/yellow color. This is one of the few minerals that can form crystals ranging anywhere between gemmy and transparent to opaque and metallic-like. Opaque or cloudy sphalerite tends to be most abundant since iron easily replaces zinc in the process of formation.

Chalcopyrite is a brass-yellow colored mineral and an important copper ore. When weathered, chalcopyrite loses its metallic luster, turning a gray-green color. When exposed to acids, the tarnish can develop a red, blue, or purple iridescence: this acid-treated material is often sold under the name peacock ore.

Galena is a lead-based mineral and the primary ore of lead, and has been used for its lead content for thousands of years. Galena typically displays a gray metallic luster and forms cubes or octahedral crystals. The chemical composition of galena is PbS.

While galena will not pose a health hazard by sitting on the shelf or even from casual handling, we suggest washing hands following handling due to the mineral's lead content.