Blue Crystals

What Makes Minerals Blue?

Blue is one of the rarest colors in the mineral kingdom, which is why blue gemstones (sapphire, tanzanite, lapis) command premium prices. Most blue minerals get their color from either copper (azurite, chrysocolla, turquoise), iron-titanium charge transfer (sapphire), or vanadium (tanzanite). A few achieve blue through Rayleigh scattering - the same physics that makes the sky blue - where microscopic particles scatter shorter blue wavelengths preferentially.