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Romancing the stone

The white calcite veins vividly contrast against the oppressive black shale, running hither and thither as though emplaced by Jackson Pollack rather than hydrothermal fluids. A flash of green catches the eye from out of the muck and dust, the mesmerising deep green of a Muzo emerald.
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Muzo emeralds fresh from the face in Boyaca, Colombia

Paul Harris in Muzo, Boyaca, Colombia

While emeralds can be found on five continents, Colombia's emeralds stand head-and-shoulders above the rest for their deep Muzo green colour, named after Muzo, the town in western Boyaca, in the eastern cordillera at the heart of the world emerald business.

Their deep green colour stems from their being vanadium-rich green beryl, and it makes them the emeralds of choice for ultra-luxury brands such as Cartier and Rolex.

First mined by indigenous tribes long before the arrival of the Spanish Conquistadores in the 16th century, emerald production in Colombia had remained a feudal activity until recently, with subsistence workers exploited like serfs by the ruthless and continually warring emerald tsars.

The biggest and baddest of these was Victor Carranza, who fought his way up from nothing to controlling the Muzo district with an iron fist and a private army which even held the FARC guerrilla at bay as he amassed a vast personal fortune. Having survived innumerable assassination attempts over the years, the aging Carranza and other warlords wanted things to change and reached out to a former US diplomat for help.

Charles Burgess was approached by Álvaro Jarro, the bishop of Chiquinquirá, who years before had officiated his marriage ceremony to a woman from Boyaca. Jarro had been instrumental in negotiating the 1990 peace agreement to end the emerald war and approached Burgess to see if foreign investors would be interested in coming to the emerald fields. Burgess found interest among a group of investors from Texas prepared to invest in the emerald business and bring it into the 21st century and so began an unexpected and unusual second career for him.

Minera Texas Colombia (MTC) was born in 2009 and took operational control of the Puerto Arturo mine on a profit-sharing basis on the condition that Carranza retired and left the day-to-day operations to MTC.

"My wife thought I was insane due to the history and wouldn´t tell her friends what I was doing. My former colleagues in the Bogota embassy thought I'd gone over to the dark side. We couldn't open a bank account and even our lawyers in Bogota didn't want to take us on," Burgess told Mining Journal at the MTC camp in Muzo.

With Carranza finally succumbing to cancer in 2014, MTC bought the mining titles shortly before he died. "We were extremely cautious and sent in an army of lawyers to Colombia to undertake due diligence to ensure everything was squeaky clean. Operating the mine for three years before making the purchase had given us the opportunity to fully study the situation," said Burgess.

 he uerto rturo mine in uzo oyaca olombia The Puerto Arturo mine in Muzo, Boyaca, Colombia


The task facing MTC was massive.

Mechanising mines where exploitation had been manual for centuries was challenging enough, but replacing feudal control structures based on power, patronage and violence with a corporate culture and procedures for a workforce with limited education meant undertaking huge cultural change.

Much of MTC's effort focused on people, creating dignified jobs through implementing improvements to health and safety, while weeding out members of the workforce who had participated in the violence.

Prior to the arrival of the company, the mines were operated by subcontractors with teams of 15-20 people who were paid by the owner if they found something. "It was treasure hunting, not a real job, and treasure hunters tend to fall out. We had to change their mentality towards a steady job with benefits. There is always going to be an issue with people wanting to walk off with an emerald but gradually people have realised they are part of a company which is helping to build a community," said Burgess.

"We brought in fair salaries which are paid on time, benefits, welfare, uniforms, safety gear, recreational activities and social projects to improve the quality of life for workers and their families. People are proud of their jobs and want to protect them," Alberto Saldarriaga, director of communications and corporate affairs, told Mining Journal.

With MTC approaching its 10th anniversary in November, Burgess believes a key success factor in the transformation was a lack of mining experience. "We were very fortunate in not being a mining company with preconceived notions about running a mine, so we came in with an open mind and wrote our own book. If we had of come in expecting to operate like a regular mining company we would have failed," said Burgess.

The company has been investing about US$20 million a year in capex to modernise the operation. The main ramp—one of six—is now 1,000m long and descends at a 12% gradient for a vertical distance of 150m with levels developed every 15m. Exploitation is via the cut-and-fill method using square set stoping, with an average of some 30 fronts active at any one time.

The use of modern mining techniques such as bolting, shotcreting, steel sets and ventilation is enabling MTC to mine deeper than was possible before and taking the mine into new territory. "We are down 150m vertically, but we have no idea how far down the emeralds will go. It could be the deposit gets richer as we go deeper as that is where the fluids came from," mine manager Daniel Guerrero told Mining Journal.

Modernisation and mechanisation has improved access and safety with mechanised equipment undertaking mine development with orange Joy scoop trams shouldering much of the work. Emerald extraction is still a manual process as machines or explosives would damage the friable emeralds. "Modernisation has allowed us to increase productivity, advance quicker and be less wearing on the people, but extracting the emeralds is still done by hammer, chisel and knife," said Guerrero.

 meralds in situ in uzo oyca olombia Emeralds in situ in Muzo, Boyca, Colombia

The mines are wet due to the porosity of the shale, and hot, even with modern ventilation. When a zone of interest is found and a vivid green glistens in the rocks, activity grinds to a halt as the miners withdraw and geologists move in with their hammers and chisels for extraction, and a security team to monitor and record the extraction process. Extraction is slow like archaeology as the emerald-bearing vein is carefully chiselled out. Unlike most mining, the mine plan cannot revolve around extracting a certain tonnage each day to feed a mill but on having enough development faces to sustain a baseline. "Volume doesn't relate to the quantity of emeralds," said Guerrero.

MTC said production in 2016 was 719,687 carats and in 2017, 1.3 million.

Good geological conditions for hosting emeralds often mean poor ground conditions so as production inches forward, overhead support inches ahead to protect workers, with wooden pillars put in every 1.5m or so with the tunnel sides boarded up.

Once the stones are extracted, they are put in secure bags and taken to the surface for initial grading by size and colour, before being sent for cutting at the company's facility in the duty-free zone near Bogota airport. Modernisation means traceability, both for the company to keep track of its inventory and protect against theft and to meet ever-increasing requirements of the jewellery industry where the stones ultimately end up. "We video the stones being extracted, their location and record the date and hour of their birth. This goes onto a data sheet with a QR code, so each stone is traceable," said Guerrero.

Unusually for a mine, the main constraint on increasing production is people, but not in the way one would think.

"The main constraint is the supply of security personnel. We cannot bring on more workers if we don't have the supervisors and security personnel we can trust. One gem could pay the operating costs for a year, so we have to be very vigilant in the mine," said Burgess.

MTC is also innovating in its mine to market model which captures more of the value chain for the company, reinforces the traceability of the stones and further removes production from the cloak and dagger nature of the old-time emerald trade. Emeralds are cut by MTC company Emeralds of the Andes (EDLA), the largest and most modern emerald-cutting laboratory in the world. And MTC is looking to extend such innovation to create a jewellery brand rather than just exporting stones for others to set into pieces, an idea which is gaining support from the government.

"Blood diamonds raised consciousness about the ethical consumption of gems. Our traceability measures allows us to guarantee to our customers they were mined legally and ethically and were monitored from the mine to the consumer. We are reasserting in the high-end emeralds market that the Muzo mine produces the best emeralds in the world and that buyers can have confidence they are mined ethically," said Burgess.

As investment in the mine continues, the company aims to double the depth of the ramp and drive it down to 400m, depths emerald mining has never touched before. "We will open up a tremendous area which has never been mined before. We have no doubts about the future of the mine," said Burgess.

Modernisation has also included the development of a closely guarded exploration methodology to identify areas with the characteristics and potential to host emeralds. This has meant building a geological model from scratch using drilling, geophysics and other methods due to the lack of exploration in the past and the lack of analogue deposits elsewhere in the world to learn from, among other hurdles.

Exploitation used to be empirical with miners working by sight and looking for rock with calcite veins in the black shale, the glitter of pyrite and grey dolomite. Exploration drilling essentially seeks to encounter these pathfinder minerals to identify areas conducive for emeralds. "The shale has been folded which created openings and the positive conditions to grow the crystals," said Guerrero.

"It was a challenge to win the trust of the miners who had been operating the same way for generations and who could pick up on slight changes in the rocks and know when emeralds were near, especially since the geological team includes women. This meant combating superstitions about women underground bringing bad luck and scaring the emeralds away. But we won their trust by finding new zones," head of exploration Luis Giraldo told Mining Journal.

The Muzo region has undergone a transformation from being a place where mining was a curse which bought violence and tore the fabric of society apart, to one where mining has brought hope, opportunity, development and has brought society together.