特征 Gems & Gemology, Winter 1996, Volume 32, No. 4

An Update on Imperial Topaz from the Capao Mine, Minas Gerais, Brazil


The Capão mine is one of the oldest and most productive fully mechanized Imperial topaz mines in the historic Ouro Preto area of Minas Gerais, Brazil. Bulldozers, water cannons, and dragscrapers are used in two main pits to remove the thick brown overburden for processing to recover topaz crystals in a broad range of sizes and colors. The rarest color is pinkish purple to purple. Heat treatment will turn some brownish yellow or orange Imperial topaz to "peach" or pink. Preliminary testing suggests that there may be a difference in fluorescence between heat-treated and non-heat-treated topaz.