They lie about 8 kilometres (5.0 mi) by trail west of the village of Muzo in the Department of Boyacá, and embrace about eight great open cuts, closely grouped, occupying a portion of a steep walled valley, that of the Itoco, also called Quebrada del Desaguadero, an affluent of the Minero River which empties into the northward-flowing Magdalena, the great artery of commerce for central Colombia.

The emeralds occur at other points in the mountainous region of Boyacá, not only the Muzo locality has been productive but Coscuez, La Pita, Chivor and Peñas Blancas have been highly active in modern times.

[citation needed] Since the 1970s, Brazil (Class 3) has become a recognized producer of emeralds albeit of a lower quality than Colombia.

It has been reported, in Colombia near Bolívar, Vélez, Department of Santander, and tradition points to the Manta Valley near Puerto Viejo in Peru as a source, but it seems probable that all the "Peruvian" emeralds came from the Colombian deposits.

Originally a large Mesozoic basin, the Cordillera is composed of geological formations comprising interbedded sandstones, limestones, black shales and evaporites.

[4] From observations of several of the mines in the area, the mineralization is favoured in the fractures within an alteration halo around large regional faults in particular formations.

These emeralds are produced from a unique fold-hinge style of mineralization, not observed on other projects in the district, which is related to the Alto La Chapa anticline.

Existing exploration accesses the unique mineralization on 4 different levels, demonstrating good continuity, this target remains open at depth.

[6] The Muzo Formation (K1m - Hauterivian-Barremian age) is a unit outcropping in the sector of Las Pavas, Peñas Blancas, and Coscuez.

Towards the middle of the segment claystones occur and albitized limestone, at this level appear a brecciated and mineralized zone with veins of calcite and sheets of oxidized sulphides.

In the upper part, intercalations of black shale with gypsum flakes and abundant pyritic micritical concretions appear, some with ammonites.

[citation needed] The mining region, despite its poor reputation, is actually safe and community orientated, the violence is now a faint memory of the past.