Monthly Archives: September 2016

How Mining Works, Volume II

We last left the Reverse Circulation drill out in a waterlogged field in Burkina Faso.  It’s 3 AM.  Night and day the drill chews through the soil and rock, manned by a crew of six drillers who station the rig at pre-identified GPS coordinates, drill to the depths and angles desired by project geologists, and then retract the drill rods to move on to the next hole.   At each borehole they leave behind orderly rows of sample bags containing samples from 30, 60, 120 meters deep.  The crew wears earplugs to protect themselves against the relentless hammering of the air compressor, and they work under the blazing beam of projection lights whose halogen beams banish shadows from the work zone.  These are probably the brightest lights in a 100-kilometer radius.  You cannot see or hear anything that is not within a 50-meter radius when you are next to a drill rig at night.  The crew moves across the dark fields leaving behind narrow boreholes, tracks from the massive tires of the drill rig, and orderly rows of sample bags that will be sorted by field crews in the morning and then transported back to the mining camp.

And then suddenly another light comes to life in the fields.  A motorcycle cruises along the laterite road, lights low, orienting itself towards the distant glow of the halogen lights, and pulls over into a field of knee-high sesame plants bending to earth under the dew.  Two men get off and one of them strides over to the neatly arrayed sample bags of a fresh borehole, pulls a pair of bulky Starsky and Hutch era headphones over his ears, and flicks a switch that brings the metal detector to life.  The red light blinks.  He runs the pad of the machine over the sample bags until it starts to whine in his ears, and the two men pull out the sacks of samples from meters 28-31 and wrestle them on to the back of the bike.   They spin around, carry the bags back to their camp, and then head out to chase the drilling crews again.  At dawn they’ll sleep, then later sift the stolen samples to see if the geologists were correct in identifying something interesting.  If their night goes well they can get a few grams of gold.

These men are orpailleurs.  It’s a French word that’s tricky to define, but it means prospectors, sample thieves, hopeful opportunists, career gold diggers, journeymen, and former cotton farmers.  They are men and women and children that look for gold flakes wherever they can be found.  They sieve for gold in riverbeds, dig narrow shafts by pick and shovel 15 meters into the ground, use metal detectors to search for surface gold and lift sample bags by dead of night.  Wherever the mine is, the orpailleurs can be found.  I see them on every trip that I take out to the field, typically riding in a peloton of three or four motorcycles with two men on each, one guy steering and the other guy holding the metal detector and shovel and picks.  Some of them search hopefully in low areas or exposed fields looking for a lucky find, and others are clustered in camps that have found a deposit and work tirelessly to pull it from the ground.  Conservative estimates suggest that there are hundreds of them on the concession, which is not atypical.  Similar to people brown-bagging liquor on a hot day, out of courtesy they wrap their picks and detectors in sacks as we drive by in our Land Cruisers, but they know who we are and we know who they are.  You can’t hide a 15-meter mine shaft.  They wave to us.

Even 800 years ago spotty plague victims in Europe might have heard about the riches of Timbuktu, where women’s ears drooped under the weight of massive gold earrings.  Salt and gold used to be key West African exports, although the salt market ain’t what it used to be.  Gold, meanwhile, has kept climbing steadily, and modern estimates suggest that 12% of the new gold brought to market annually has been produced by informal miners.  Most of the orpailleurs are people who don’t have a lot of alternatives to gold hunting.  Many of them are from the Mossi ethnicity of central Burkina Faso, which is the majority group but suffers from living on extremely flat and arid land.  Some of the orpailleurs are local people who were forced to find new revenue when the bottom dropped out of the lucrative export market for cotton a few years ago.  Others are Malians or Ivoirians who come to Burkina to seek treasure while escaping political unrest in their own countries.  A lot of factors influence whether people become orpailleurs: rainfall in central Burkina, the market price of cotton, the results of the presidential election in Côte d’Ivoire.  Interestingly, the number of orpailleurs doesn’t seem to fluctuate much according to the global price per ounce of gold itself.  All other commodities rise and fall, but gold is always worth its weight in gold.

Objectively, it’s not an attractive line of work.  Orpailleurs either strike rich or go destitute, and there is no in-between.  It’s an absurdly dangerous occupation.  They dig unreinforced shafts into the mud, which can flood or collapse instantly.  The ore that they extract may contain gold flakes amidst the dirt and rock, but to separate and refine it they run the ore through a bath of mercury or cyanide to separate out the heavy metals.  Their picks and metal detectors are fronted by suppliers who demand a heavy percentage of the orpailleurs take, so steel shovels are repaid in gold.  Those who don’t repay or hide discoveries are killed sometimes, and there’s no lack of pits for the bodies to disappear in.  A walk through an orpailleur camp is a study in hazards.  Children under ten smash rocks with sledgehammers, women sieve muddy rivers with the same bowls they’ll use to make dinner, men descend crooked shafts into the muck, and blue tarps line depressions in the ground where ore dissolves in brilliant blue pools of cyanide to be raked through later.

Like any good story, there’s a plot twist.  Although neither side likes to talk about it, there is a peculiar symbiosis between the formal mines, like where I work, and the orpailleurs.  People have been hunting for gold around here for centuries, but modern orpailleurs watch exploration crews closely and learn from them.  They observe what areas of the terrain are the most promising to scan with their metal detectors, and it didn’t take them long to learn how to snag sample bags and get access to deposits that may be 100 meters beneath their feet.  The other night I had a beer with a geologist and I asked questions about the timeline for how a gold exploration project develops.  Advanced exploration stages make sense to me: when you’ve identified the zones where gold is present, you must drill a lot of samples to determine where those deposits are concentrated and what are the most viable methods of extracting them.  But how do you know where to start exploring in the first place, in a region that has never been commercially mined before?  He explained to me about the belts of subterranean rock that have characteristics suggestive of gold deposits; but these belts are massive and can run from northern Mali down to the Atlantic coast.  How do you know where exactly to start drilling to explore in earnest?  Basically, he told me, they look to the orpailleurs.  Areas that have a high concentration of informal miners are likely to have promising deposits that can be mined at a large scale.  For all of the geological studies and diamond core drills and ground penetrating radar at our disposal, the initial decision to buy a concession and launch an exploration project depends in part on the guys riding through the sesame fields with metal detectors.




Burkina Faso 2009


(I got these photos from here and here and here.  All are public domain pictures of orpaillage sites in BF.  For various reasons I won’t upload pictures from my work site.)