Mineralpedia · open reference
A free reference encyclopedia of crystals and minerals.
Written by collectors for collectors. 27 species published so far — chemistry, formation, identification, market value and meaning. Every photo sourced from Wikimedia Commons under open licenses, with full attribution.
Mohs 7Tiger's Eye
SiO₂ · Silicates
Tiger's eye is a pseudomorph of quartz after crocidolite asbestos fibres, producing strong golden chatoyant sheen. Mohs 7. South Africa is the main source.
Mohs 8Topaz
Al₂SiO₄(F,OH)₂ · Silicates
Topaz (Al₂SiO₄(F,OH)₂) is an aluminum silicate with fluorine. Mohs 8, perfect basal cleavage. The 'Imperial' orange-red variety from Ouro Preto Brazil is the most valuable.
Mohs 7.25Tourmaline
(Na,Ca)(Mg,Fe,Li,Al)₃Al₆(BO₃)₃Si₆O₁₈(OH)₄ · Silicates
Tourmaline is a borosilicate mineral group with 14+ species, famous for its rainbow of colours. Mohs 7. Brazil's Paraíba neon-blue variety is the most expensive coloured gem on earth.