TAO project: analytical traceability of gold in French Guiana

In conjunction with the WWF in French Guiana, BRGM conducted the TAO project in order to identify the geographical provenance of gold and thereby combat illegal gold mining.
22 February 2016

TAO – Analytical traceability of gold in French Guiana – The issues involved

The goal of the TAO project, conducted by the WWF in French Guiana in partnership with BRGM, is to identify the provenance of gold and thus help combat illegal gold mining. In this first episode, we look at the importance of tracing the origins of gold in French Guiana (2015).

© BRGM/WWF French Guiana

The Guiana Shield is one of Earth's richest environments. The Amazon has amazing biodiversity, with over 1 in 10 of all species. It also plays a key role in the planet's climatic balance. In the Amazon, the Guiana Shield is particularly important. Its biodiversity differs from elsewhere in the Amazon. This part is now also the best preserved of the Amazon massif. The main threat to the forests of the Guiana Shield is unmonitored, illegal gold panning. Gold panning is the mining of gold. When illegal, it is done without respect for the environment or for workers, with a particularly harmful impact on natural environments and thus on the resources of populations in the Guianese interior. Illegal panners exploit any deposits they find, whether within or outside protected areas. So we have deforestation, the destruction of rivers and river pollution several hundred kilometers downstream caused by suspended matter.

This milky, muddy appearance means the water is unfit for aquatic life. Another big pollution source is mercury, used by miners in the process of gold extraction. Mercury is highly neurotoxic, a violent poison for humans and living beings in general. The problem is that once mercury is present, it's hard to get rid of. The pollution lingers. It is estimated that 70-80% of gold now sold worldwide is of unknown origin, and thus potentially illegal. The problem is, it's hard to distinguish between gold from a declared mine and gold from an illegal mine. The TAO project now underway will tell us more about the physiochemistry of Guianese gold, and identify possible indicators of geographical origin. Every year in Guiana, some 10 tonnes of gold are produced illegally, i.e. 5-10 times more than that produced officially.

We therefore collected samples of gold from mines across French Guiana, to have a broad geographical coverage.

These samples are sent to the BRGM labs in Orléans, to look for trace elements in the gold that might give an indication of the gold's geographical origin.

TAO – Analytical traceability of gold in French Guiana – Analyses

The goal of the TAO project, conducted by the WWF in French Guiana in partnership with BRGM, is to identify the provenance of gold and thus help combat illegal gold mining. In this second episode, we explain the analyses needed to trace the provenance of gold (2015).

© BRGM/WWF French Guiana

In characterising gold, it is currently hard to know what might be the most effective “signature” for tracing this gold and being able to say, with confidence or 100% certainty that it comes from Guiana and nowhere else. The grains we're working on have been modified by streams, and so have certainly lost some original features. They may have lost their chemical characteristics, their shape. They've probably lost mineral inclusions initially present, from which we can trace the deposit. These are the parameters we're trying to bring out to find the source of the gold. To characterise the provenance of our gold grains, we've set up a whole series of tests. Earlier we mentioned morphoscopic characterisation, i.e. the shape of the grains, the roundness and wear, to see how far they've travelled.

Then we move on to "semi-chemical" analysis, using a scanning electron microscope, plus the characterising of mineral micro-inclusions that might be present, symptomatic of a known deposit. We move on to chemical analysis, this time with more precision, on an ad hoc basis, using the electron microprobe, with detection thresholds sometimes as low as a few hundred ppm, allowing certain elements to be measured. For others, however, present at even lower levels, say up to a few dozen ppm, require techniques such as laser ablation. The ultimate tool we use to test our gold grains is isotopic analysis, especially lead, to try to get yet another signature. Together, these various parameters, of chemical content, morphology, and isotope ratios, will be combined, to try to define a signature of a gold sample from a known deposit.

TAO Analytical traceability of gold in French Guiana – Applications

The goal of the TAO project, conducted by the WWF in French Guiana in partnership with BRGM, is to identify the provenance of gold and thus help combat illegal gold mining. In this third episode, we look at the practical applications of the physico-chemical traceability of gold (2015).

© BRGM/WWF French Guiana

The problems caused by illegal gold panning are many. First, of course, is the impact on the environment, on this preserved forest, especially in the Guiana Amazonian Park. There are other impacts, in terms of crime and, therefore, safety, the safety of local people who live close to the garimpeiros, but also of these garimpeiros, because of all the crimes that can be committed in the forest.

Gold tracing should have definite applications in law, in several ways. The first is the possibility for physiochemical comparison of samples seized in the context of legal proceedings and samples from the site, to confirm the gold's origin. The next is that, internationally, we envisage seizing criminal assets abroad, simply by identifying the origin of gold found at trading counters in Surinam or Brazil, as most gold extracted illegally in Guiana ends up in Brazil or Surinam.

We're at a mining concession of the Boulanger Mining Company. As a mining operator, and President of the ORkidé business cluster, I find this a good move, in that it will help differentiate gold produced by legal operators from that produced illegally. As you probably know, Guiana has many illegal operators. Aside from the fact that illegal operators loot reserves that could be legally exploited, they also give mining a bad image, as people can't always tell the difference between what goes on in legal mines and in illegal mines.

SAAMP has been a leader in precious metals for over 40 years, in France and overseas. We're based in French Guiana. The interesting thing with the TAO process is being able to offer gold of certified Guianese origin. The idea is to have a product, of controlled designation of origin, that is 100% "made in France". We work alongside manufacturers, jewelers, the jewelry industry, investors and industry in general. We sell them our gold and it would be valuable for all our customers to be offered gold that is traceable, clean and French.

It's important to know that gold has been extracted according to standards such as a controlled designated origin, or to economic, environmental or organizational standards, in the field. For that, you need a set of standards that are solid and verified in the field, at the mine. Physical traceability is about guaranteeing to consumers that their gold comes from a specific site and mine.