THE GEMSTONE LIBRARY
Rainbow Pyrite
Rainbow Pyrite is a descriptive name for pyrite showing iridescent surface colors. The underlying mineral is iron disulfide, FeS₂.
Pyrite and its appearance
Pyrite belongs to the cubic crystal system and is usually metallic and brass-yellow. Its familiar forms include cubes, octahedra and pyritohedra. The Handbook of Mineralogy records that its surface can become darker and iridescent as it tarnishes.
The rainbow effect
The colorful appearance describes a surface effect, rather than a separate mineral species. Color alone cannot establish a specimen’s locality or whether its surface has been treated. Those details require provenance or examination of the individual piece.
Our collection
This photograph shows our December 2024 material supplied as Rainbow Pyrite. No specimen-specific laboratory result, locality or treatment determination is presented for these photographed pieces.
Care
Keep pyrite specimens dry and avoid soaking. Museum conservators document that humidity can promote oxidation and damage susceptible specimens.