Topaz with lepidolite
Most topaz come from pegmatites. This large crystal capped with lepidolite is naturally blue. This is rare in nature, however, and most blue topaz is man-made by irradiating and heating colorless or yellow-brown topaz. The chemical composition of topaz is Al2 SiO4(F,OH)2.
Image Number: 142207
Catalog Number: 95-40167
Gift of J. J. Trelawney
Locality: Virgem da Lapa, Minas Gerais