Coscuez Mine, San Pablo de Borbur, Western Boyacá Province, Boyacá Department, Colombia
The deposit is in the western emerald-bearing region. It is 10 km north of the Muzo deposit and is similar in geological structure and mineral composition. It comprises two emerald-bearing vein-veinlet zones, which strike northeasterly and dip steeply. A second conjugate system of almost horizontal mineralized fractures is distinct.Emeralds have bluish tint. Ringsrud (1986) stated that these crystals were the best Colombian emeralds.
Ref: E.Ya. Kievlenko (2003) Geology of gems, pp. 100 - 101