Collection: Marcasite

Marcasite, a polymorph of pyrite, is an iron sulfide mineral (FeS₂) that crystallizes in the orthorhombic crystal system. This brass-yellow to pale bronze mineral is prized by collectors for its distinctive spear-shaped crystals, radiating clusters, and vibrant iridescent oxidations that develop over time. Marcasite often forms striking associations with calcite and barite, creating aesthetically compelling mineral specimens. Through geologic mineral replacement processes, marcasite can also beautifully preserve fossils, capturing ancient life in metallic detail. To maintain the long-term stability of marcasite specimens, collectors should store them in low-humidity environments with silica gel desiccants to prevent deterioration.