For over 200 years, the only known source of imperial topaz has been a small mining district near Ouro Preto. One of the oldest and most productive mines in the district is the Capão do Lana. This article examines the history of the Ouro Preto district as well as the geology of the area and occurrence of the topaz. Special attention is focused on the relatively sophisticated recovery methods used at the Capão do Lana mine. Also discussed is the gemology of this most prized color variety of topaz.
For over 200 years, the only known source of imperial topaz has been a small mining district near Ouro Preto. One of the oldest and most productive mines in the district is the Capão do Lana. This article examines the history of the Ouro Preto district as well as the geology of the area and occurrence of the topaz. Special attention is focused on the relatively sophisticated recovery methods used at the Capão do Lana mine. Also discussed is the gemology of this most prized color variety of topaz.