Feature Gems & Gemology, Summer 1986, Vol. 22, No. 2

The Coscuez Mine: A Major Source of Colombian Emeralds

The Muzo emerald district, in Boyacá, Colombia, contains several mines. Although the Muzo mine is undoubtedly the best known, the Coscuez mine is rapidly gaining significance as a major source of fine emeralds. Yet few in the trade outside of Colombia are aware of the importance of Coscuez or know about the emeralds mined there. The Coscuez mine is literally hundreds of years old, and its history is closely tied to that of Muzo. Located only about 10 km apart, the two areas also share many geologic features and both are currently exploited using open-cut mining methods. The Coscuez emeralds are similar to Muzo stones in their physical properties, but they occur in a somewhat broader range of hue and saturation. Prospects for even greater production at Coscuez in the future are good.