Flying Into The Heart Of The Colombian Emerald-Mining Region

Bogotá, Colombia played host to the First World Emerald Symposium from October 13 to 15, bringing together various stakeholders of the Colombian and international emerald industry. Vital to the event were the various presentations made by Colombian (FEDESMERALDAS) and other trade organizations, private individuals, laboratories, scientists from universities and large mining companies, such as Muzo International and Gemfields. Topics covered a broad range of information creating an atmosphere for the exchange of data between attendees. The presentations featured an introduction to the geology of emerald formation, mineralogy and the engineering side of mining operations, focusing on various emerald mines around the world (www.worldemeraldsymposium.com).


GRS Gemresearch Swisslab AG was invited to take part in the Symposium in order to address the topic of color grading of emeralds. Following the presentation by Dr. Adolf Peretti, he was part of an expert panel of debaters who discussed topics such as the marketing of emeralds and various laboratory issues, including disclosure of treatments, color grading and origin determination. And he also organized an expedition into the remote areas where Colombia’s main emerald mines are located.

FEDESMERALDAS, the Colombian Emerald Federation, the country’s national organization which represents emerald producers, merchants, dealers and exporters, organized trips to various key mining sites in Colombia’s Eastern Andes ‘Cordillera Oriental’. Large mining companies openly welcomed a group of people to acquire first-hand insight from miners and experts in the field. This experience provided a unique opportunity for the group to cobine theoretical knowledge with practical field experience. GRS organized its own small expedition in tandem with the larger group’s expedition at the three different mining areas of Chivor, Cunas (La Pita area) and Muzo. We had to hand over our equipment for our filming and sampling activities, since we did not want to disrupt the organizers of the official field trip.

The expert GRS group included Adolf Peretti and Willy Bieri, and was accompanied by Jean Claude Michelou, former ICA Vice President, Colombian emerald expert and advisor to the UN, as well as former ICA President Wilson Yuen from Hong Kong. The expedition was conducted via private transportation as well as helicopters that provided efficient use of time for our visits to the mines.

The GRS-sponsored expedition had the following objectives:

  • Visit the mines, meet the miners and interview them about their mining experiences
  • Enter the mines to collect rocks and emerald specimens of known origin
  • Survey the mines with a drone to gather aerial reconnaissance
  • Obtain film and photographic footage of the interior and exterior of the mines

This field trip provided the foundation for future GRS seminars with a focus on Colombian emerald mines. In this article, we cover our expedition and share some of our experiences via a selection of images and video clips. Video clips of interviews with the miners and geologists are also included (see box). We also visited the TMC (Texas Mining Company) Muzo mine during the trip, but no filming was allowed inside that mine. So, instead, GRS offers photographic images and clips of these mines and inside the tunnels from previous expeditions to the Muzo mines from our archives (Figs. 22-24). As our recent inspection revealed, the documentation is still valid and accurately represents some aspects of current mining activity and their geology.

Figures 1-12

Expedition to Chivor

The journey to Chivor from Bogota takes about 4-and- a-half hours using a 4-wheel-drive vehicle. The emerald mining area we visited is situated in the Western Cordillera of the Andes (4° 51’ 10.08” N, 73° 23’ 6.72” W). On arrival, we were granted access to a private mine operated by SOESCOL Ltda and managed by Ubaldo Montenegro. The miner drove us in his specially designed 4×4-wheel vehicle to ‘San Gregorio’ ,one of his local mining titles. A few mining shafts were visible and we chose one for a closer inspection. We had to walk 2.7 km inside the mountain for a total of 5.4km there and back. This was a hard two-hour walk under conditions of extreme heat and high humidity. We were equipped with helmets, lamps and special boots plus a sufficient water supply to withstand the tunnel trek that took us deep into the mountain with temperatures reaching far above 40°C. It was necessary to pass a heavy steel door that keeps uninvited guests out of the mine. Inside the mine we encountered an emerald-bearing vein that had been mined only a couple of hours prior to our arrival. This was where we also met with miners who worked this part of the shaft. It was a rare opportunity to document the geology of the veins and acquire emerald material that had just been mined at this exact spot. One of the authors (Adolf Peretti) hammered Colombian emeralds directly from the rock (Fig. 3). Such samples are vital as they can be used for comparison against the results that are published in trade literature. They were carefully labeled and packaged for later chemical and sulfur isotope analyses. It was interesting to see the large and beautiful pyrite formations

that accompanied the emeralds in the host rock (Fig. 5). The mine owner allowed us to operate a public licensed remote-controlled drone in order to properly survey the landscape. The drone allowed us to document the large- scale geological formations of the mine with a true bird’s-eye perspective (Fig. 6). We were able to acquire commercially relevant emerald rough of various shades of green from miners from a different tunnel (Fig. 11). These samples were later polished in our laboratory for calibration of different color varieties from the Chivor mining area.

Outside the mine, we came across some hard working Colombian miners (Fig. 9). Their faces were covered with black graphite soot from underground exposure and the rock particles of its surrounding host rock to the Colombian emeralds. The green rough emeralds were in stark contrast to the miner’s hands. Those miners’ hands symbolize the extremely hard conditions involved in this kind of mining activity.

Jean Claude Michelou assisted us with translation during the research sample acquisition for the laboratory using his expert negotiating skills and knowledge of the local customs (Fig. 4). The mines appeared to be involved in relatively small-scale mining. It appears that there were many liberties taken with regard to security and safety as we realized when comparing it with other very large mines in the east of the Andes. Our car was equipped with a GPS, which allowed us to return to Bogota the same day through the total darkness of the remote tropical areas.

Expedition to Cunas (La Pita Area) and Muzo

The following day we flew from Bogota by chartered helicopter but were only allowed to fly into the Cunas mine (5° 35’ 49.20” N, 74° 5’ 12.94” W). The TMC Muzo mine did not grant us landing permission. The Cunas mine, however, is very close to the Muzo mines. Both mining areas are situated among beautiful mountain landscapes along the River Mineros; approximately 40 minutes flying time from Northern Bogota airstrip Guaymaral. The flight path follows some fantastic scenery. It provided us with an impressive view into a natural paradise nestled in a classical area that had been riddled with conflict from different origins in the past (Fig. 25). However, the region is now “pacified” and this area was exceptionally made accessible to us. Previously, only very important emerald dealers were granted access to these mining areas. This was not possible without the heavy protection that the groups relied upon for security measures.

The Cunas mine is a medium-sized enterprise of commercial importance professionally organized by the Esmeraldas Santa Rosa company. The helicopter-landing pad is idyllically situated atop one of the steepest mountains emerging from the emerald-bearing river (Fig. 13).

We carried out a few extra flights around some very dramatic mountain peaks in the area (Fig. 25). On arrival, we were permitted to operate our drone over the Cunas mining area. The drone was followed by a few vultures, which constantly circled the mining camp. At lunchtime, we took the opportunity to interview the mine operation manager Alejandro Lemaitre (see box). The miners, we noticed, were being served food from a very clean, hygienic kitchen. We then encountered some miners performing gymnastic exercises in preparation for the arduous work that followed during their next shift (Fig. 16).

The descent from the Cunas mining camp from the top of the mountain to the river was steep, and heavily armed guards were observed on the way (Fig. 15). The mining operation is constantly confronted with air quality difficulties inside the tunnels, which have to be continuously monitored (Fig. 19). The mine tunnels are re-enforced with wooden supports. Small steel carts bring out the black crushed rock from the mines. Emerald-bearing veins are sealed in special bags right after they are discovered and are labeled with detailed information and then secured by a supervisor. It was possible to take some rock samples, but they did not contain emeralds. Of our two film cameras,
one stopped working when the temperature and humidity reached extreme highs. Large amounts of water were constantly being pumped out of the mines. The vein formation was different here. Some geological sketches could be drawn to record the details of the direction of shear zones, calcite veins and pyrite formations.

We left the area to continue to Muzo. While Willy Bieri continued his journey by helicopter to overfly the Muzo area (Fig. 20), Adolf Peretti went on with one of the miners from the Cunas mine, as well as Jean Claude Michelou and Wilson Yuen towards the Rio Minero to film. A paradise-like jungle flanks the Rio Minero.

During the filming, the river sounds were accompanied by a symphony of sounds from the jungle’s abundant wildlife. It was interesting to imagine that this area was once dominated by the Muzo Indios considered to be among the mightiest warriors of the Andes. We stayed overnight and approached the Muzo mining area by private car. On the way, we sampled some rocks for research purposes and filmed the ‘eagle nest’ of the ‘ legendary Emerald Tsar and miner Victor Carranza. Before he passed away, he opened the way to the Texas Mining Company (TMC) operation. We finally entered the large mining area of TMC and were carefully vetted by security personnel before being allowed entry to the mining area (Fig. 21).

The mining area of Muzo (5° 32’ 7.12” N, 74° 8’ 47.02” W) was completely sealed off with barbed wire, roadblocks and heavily armed security personnel. Two months previously, the mining concession area of TMC was intruded upon by a large mob of several hundred locals who looted one of the mining shafts, carrying off part of a rich emerald find in one of the tunnels. Reportedly, many millions of US dollars worth of material was pilfered from the mine. There were serious hostilities and brawling between the mob and the security personnel. In the aftermath of this violent outburst, new barracks are being built to host a platoon of armed military for the protection of the mining area.

Due to security concerns, no filming was permitted once inside the secure area of the mine’s inner circle. However, we were allowed to enter the mine by a shaft (Fig. 22) and visit one of the famous tunnels of the mine (Puerto Arturo). An elevator took us 100 meters below ground. Only a very limited view of the mine without visiting the larger tunnels was granted. However, the outcrop that was being worked on presented some very interesting insight into the Muzo- style vein types (Fig. 23).

We noticed that an elaborate security system was in place. For example, the wood pillars had red and green reflectors mounted on them as an aid to orientation. This allowed one to determine in which direction the nearest safety exit could be located (by going in the direction of green and not red). This is critical in cases of accidents where huge amounts of dust would create absolute darkness. Finding the exit is crucial to survival, and this was something that was not seen in other mines.

A very professional kitchen is installed in this mine, and miners were brought to the dining area by buses. The entire mine is organized in a very professional manner. The large number of miners indicated that an additional large tunnel must have been operating which was not shown to us on this trip, and we felt that it was a pity that the mining company had to have such strenuous security measures in places. We observed all the efforts made to achieve a professional mining operation with as much extra comfort as possible for the miners. It is hoped that this operation may be able to generate peace and comfort for everyone including the small-scale miners in the surrounding regions.

The trip back to Bogota took an unexpected turn for Willy Bieri when his helicopter had to make an emergency landing in Muzo. One of its doors opened during the flight and on approach to Bogota a heavy thunderstorm was underway. It was sheer luck that a small window of opportunity could be found within this raging storm. The lightening spectacle provided us with rare footage for our Colombian emerald film and revealed an interesting aspect of the emerald mines of Colombia – constant re-orientation and reversals of fortune.

Figures 13-25


Colombia’s emerald mining looks very promising going forward with the evolution of small and medium-scale mining into larger consolidated operations by big-players like Gemfields and MTC. They allow for the introduction of modern mining technologies and larger scale geological surveys along with a combined knowledge of potential reserves and resources. These changes, however, together with new government regulations, have created some discomfort among the traditional mining sectors who fear that the uniformity and traditions of the small scale mining may be rapidly overridden. This is key to avoiding future conflict while ensuring the welfare of the local population by including them in the added-value chain of marketing downstream. It is generally agreed that FESMERALDAS’s first Symposium played an important first step in this process of discussions and awareness leading to inclusivity and prosperity for all. The laboratories will also contribute a positive and important role in promoting the finest emerald quality that the world has seen so far.♦

Expedition Videos

Link to YouTube playlist (all videos available in 1080p, Full HD resolution, for interviews subtitles CC available)


Dr. Adolf Peretti is the CEO of GRS Laboratories and Mr. Willy Bieri is managing gemologist at GRS Gemresearch Swisslab AG, Lucerne, Switzerland

Article from GRSContributions to Gemology’, reprinted in ICA InColor | Winter 2015