The deposits of Emeralds in Colombia are located in the exploitation area of Emeralds in the eastern and western sides of the Emerald belts of the eastern mountain range of the Colombian Andes. The oriental side formed during a tectonic phase in the Eocene – Oligocene, and the Western side in the Cretaceous – Paleogene, during an extensional tectonic event.
The eastern belt is made up of the mining district of Muzo, comprising the mines of Coscuez, Peñas Blancas, La Palma, Yacopí, La Pita, Quipama and Muzo, which have a very similar mineralogy, paragenesis, and geological environment.
Within the eastern belt, the following deposits of Emeralds internationally recognized for their significant production and quality are highlighted:
The mines of Muzo
It is estimated that the deposits of Muzo and Quipama have had a formation period of 33 million years
Exploited for many years before the discovery of America by the Muzos natives, they are located in the Western emerald belt in the municipality of Boyacá between the villages of Quipama and Muzo.
Exploitation areas are generally between 800 and 1.000 meters above sea level. It is estimated that the deposits of Muzo and Quipama have had a formation period of 33 million years. The exploitation of Emeralds has been done for many years in tunnels, these tunnels located on the site of Muzo are where the best quality Emeralds in the world have been found and called “drop of oil”, its color is bright green and it has a high purity presence of some calcite precipitates that provide the characteristic appearance of this type of Emerald. There are other inclusions that are characteristic and distinctive of the Muzo mines, such as parisite crystals that have a dark honey color. Colombian Emeralds almost in any field, have dentate three-phase inclusions, liquid-gas-solid, and the latter is a crystal of sodium chloride, commonly a cubic shape.
The Mines of Coscuez
Also, part of the Western emerald belt and are located a few kilometers north of Muzo, near the towns of Otanche, Santa Barbara, and San Pablo de Borbur. Characterized geologically by black carbonaceous sedimentary rocks traversed by veins of carbonates where Emeralds are held. It is estimated that the deposits of Coscuez have had a formation period of an estimated 36 million years. The Color of the Emeralds of these deposits is green with a tendency to yellowish green, have good gloss and most present faint inclusions such as the ones originated from Muzo but lacking parisite crystals.
The eastern belt is made up of the mining district of Chivor. Its deposits have an altitude of 900 to 1.200mts above sea level, the most important are Gachalá and Chivor.
The Mines of Gachalá
From the Gachalá mines some of the most famous Emeralds of Colombia have been obtained.
Gachalá is located in the municipality of Cundinamarca, east of Bogota on the eastern range and to reach it, you must travel 148 km of road from the capital. Among its best-known mines are La Vega de San Juan, Las Cruces, El Diamante, La Estrella, El Perro, La Mula and El Toro. (Saint John’s meadow, The Crosses, The Diamond, The Star, The Dog and The Bull). From the Gachalá mines some of the most famous Emeralds of Colombia have been obtained, known for their large size as 7.015 carat Emilia, found in 1969; three years later another wonderful Emerald was found, the 8.000 carat, called “The Tito” in honor of the miner Tito Daza who found it.
The Mines of Chivor
The Chivor mines, it is believed, were discovered in 1537 in one of the explorations sent by Gonzalo Jimenez de Quesada from what is now Bogotá and were abandoned by order of the Spanish Crown in the XVII century to be rediscovered in 1896. The emerald Chivor district is located in the municipality of Boyaca on the eastern ridge, 35Km to the northeast of Gachalá. Its most recognized mines are Gualí, Chivor, Buenavista, and Mundo Nuevo.
Emeralds deposits from Chivor are associated with three types of rocks: fibrous calcite veins, and veins that are identified by the precipitation of rhombohedral calcite, albite, muscovite (isinglass), quartz, fluorite, pyrite, and Emerald. Tectonic holes, polygenic hydrothermal whose size can reach 10 meters and can contain bags with emeralds, are composed of pieces of albites cemented by pyrite, black lutite and carbonate fragments. Albites rocks with black lutite horizons and epigenetic growth of albite, pyrite, mica, quartz and dolomite.
One of the most relevant characteristics of the Chivor Emeralds is the tendency of color towards blue tones due to the presence of vanadium as chromophore. The density of the Chivor Emeralds is 2, 68, its refractive index is between 1,571 and 1,577 with a birefringence of 0,006. Under the binocular magnifying glass we can see the inclusions of the Muzo Emeralds in the Chivor Emeralds, with the exception of the inclusions of parisite: iron pyrites in dodecahedron or grain shape that are very typical of the Emeralds found at the sites of Chivor. Additionally, the presence of Euclase, Rose Hydroxylapatite , Albite, Calcite and Andalusite should be mentioned, among other minerals that can be found at Chivor deposits which are parallel to the exploitation of Emeralds.
A particular variety of topaz is the sagenitic topaz containing fibers of hollow tubes filled with limonite, this topaz can be confused very easily with rutilated quartz because it contains rutile fibers. The synthetic topaz is not very common in the market and may even be more expensive than natural topaz.
In 1740, the “Braganza Diamond” (1680 carats) was found in Ouro Preto, Brazil. This diamond was thought to be the largest ever found, belonging to the Portuguese Crown, but unfortunately, it was not a diamond, just a colorless topaz.