In 2016, Metalor Technologies and the University of Lausanne (Switzerland) began a scientific collaboration to determine the origin of mined gold. This led to the creation of a new approach to validating the origin of doré – the GeoForensic Passport. This passport, which is based on the chemical composition of doré bars, was created for each supplier of Metalor using a multivariate statistical approach. Metalor now compares every doré received against that database, allowing it to identify any potentially problematic shipments.
At LBMA’s Assaying & Refining Conference, held in London on 13-14 March 2023, Dr Barbara E. Beck presented an update on her research on the GeoForensic Passport, originally presented at the Assaying & Refining Conference in 2021 alongside Dr Jonathan J. Jodry. Dr Beck’s update covered the real-world applications of the GeoForensic Passport, and the challenges and opportunities it presents. The following article is based on her presentation.
One of the major challenges in the supply chain is related to artisanal mines. For example, in 2001, there were 12 industrial mines employing 7,000 people in Burkino Faso. At the same time and location, there were 200 artisanal mines with more than one million people depending on this activity. Since then, due to the rising prices of gold, the informal mining sector has been increasing in importance. The aim now is to show whether it’s possible to use the GeoForensic Passport to prove the origin of the gold in an ASM context and allow these miners to integrate their material into the legal supply chain.
Figure 1: An artisanal mine in Peru. Photo: S. Ansermet
What do we need to set up the GeoForensic Passport?
The implementation of the GeoForensic Passport starts with a context study, which considers three issues:
(1) The structure of the supply chain. We need to assess whether the gold is the result of a single mine or a mixture of gold from several different sources. The ideal place to set up the GeoForensic Passport analysis is at points during the supply chain which experience bottlenecks, where gold naturally converges: for example, refineries, collectors, processing plants, at the border, etc. But it is also possible to implement the GeoForensic Passport at a mine.
Figure 2: A possible checkpoint for implementing the GeoForensic Passport: a processing plant in southern Peru where gold from more than 400 artisanal mines is processed. Photo: S. Ansermet
(2) The geological context. This knowledge can be useful in establishing the GeoForensic Passport, as the chemical variability of the doré bars is related to their geological context. This makes it simple to distinguish between doré from different geological areas depending on the composition of the material.
Figure 3: Miners sorting out the ore directly in the mine. La Rinconada, Peru. Photo: S. Ansermet
(3) The chemical analysis. This is the most important aspect of the context study. These chemical analyses are mostly related to doré bars, but it is also possible to work on chemical analysis of other materials, such as ore samples or even other metals (copper, etc). For our approach, we need a historical database of at least a few months’ duration, consisting of analyses of the chemical composition of doré (or ore, etc.) from one supplier. In order to understand the quality of the analyses, some information is necessary. These include the type of samples analysed (doré, ore, gold-bearing sand, etc.), the analytical protocol used (ED-XRF, AAS, pXRF, etc.), whether an existing protocol can be extended, who collects the data and how often, whether any historical analytical data is available and what are the difficulties of the specific data set.
Once the contextual study has been completed, we can start processing the data in order to identify samples whose declaration of origin does not correspond to its real origin.
We are developing several different applications for the GeoForensic Passport – some are already effective and others are under development. These applications look to address challenges within LSM refineries, ASM refineries, single mines, collectors and consumer concerns.
GeoForensic Passport in Action: ASM Mine
The GeoForensic Passport will be implemented on an artisanal mining site in the Ivory Coast, one of the oldest mining sites in the region, which is being threatened by a larger mining project nearby. The GeoForensic Passport team is working closely with the University of Abidjan, Ivory Coast, to protect this small-scale mine – and its miners and their livelihoods – by achieving the following:
- legitimising the production from the small-scale mine and allowing it to be sold at the market rate
- ensuring access to a legal supply chain – and shortening access to it
- distinguishing between gold produced in artisanal operations and gold produced in industrial mines
- strengthening the link between artisanal and industrial mining.
GeoForensic Passport in Action: Certifying Origin of Gold in an LSM Context
The GeoForensic Passport is also being used within large-scale mines to certify their production. It provides assurance that the gold originated from the mine named as its primary production site. The use of the GeoForensic Passport in this manner helps avoid reputational risk for both the mine and the refiner by guaranteeing the origin of the product.
GeoForensic Passport: For Consumer Assurance
In addition, the GeoForensic Passport is being developed to meet the end consumer’s need for due diligence, by establishing a responsible supply chain that guarantees the origin of the gold for the consumer. The GeoForensic Passport team is working with luxury product wholesalers in Switzerland to achieve this.
Traceability tools will become increasingly important, not only for gold. With the energy transition to net zero, the demand for metals will increase, leading to a depletion of ore deposits, which are becoming increasingly difficult and expensive to exploit, and consequently leading to soaring prices.
Illegal mining, in particular, is booming, as it offers economic opportunities to precarious populations. However, this type of mining is also the least likely to comply with social and environmental standards.
The traceability of raw materials and transparency in the supply chain are therefore major issues which will become even more important in the years to come, particularly for the extraction countries and for the countries in which the processing and associated industries are located. For the former, it is essential that states are able to control the conditions of production, so that operators can access a legal supply chain. For the latter, it is a question of guarding against reputational risk. The public is increasingly aware of the social and environmental impacts of mining, and there is a strong demand for guarantees regarding the origin of metals and the sustainability of their production.
What is the GeoForensic Passport?
The GeoForensic Passport is a technical tool based on geochemical and geostatistical methods with which the declaration of origin made by a supplier of precious metals can be confirmed. Confirmation of origin is possible using a series of scientific methods, following which even small percentage mixtures (<10%) can be detected. It provides a direct link between the ore body/mine and the refinery. It uses existing analytical equipment for the analysis; therefore, the method is low cost.
By design, the GeoForensic Passport is immune from declaratory fraud and is a safe, scientifically proven and reliable anomaly detection tool.
The results depend on the quality of the analyses and access to a historical database with data collected for a few months before the implementation of the GeoForensic Passport.
What are the benefits of the GeoForensic Passport?
There are many existing and potential benefits of utilising the GeoForensic Passport. Several of these are outlined below:
- The GeoForensic Passport provides a proof of origin that directly links the mined vein to the refinery. It can therefore be used to prove that only gold produced in a specific mine is found in a specific doré of that mine.
- The GeoForensic Passport is based on a reference bank of chemical analyses. For this, we don’t need to make extensive fieldwork and get reference samples from every mine. We build it up at the check point, for example, at the refinery, at the processing plant, etc.
- Analyses are very often carried out either at the refinery or other checkpoints and are therefore an integral part of the refining or pre-refining process. The implementation of the GeoForensic Passport is therefore very low cost, because it is based on these already existing analyses and can be easily integrated into the industrial process. These chemical analyses can, for example, be performed with an ED-XRF device, a relatively inexpensive instrument that has recently improved a lot. While samples do not require a significant preparation time, the equipment needs to be calibrated properly. At Metalor, for example, the ED-XRF device used for the GeoForensic Passport is calibrated for 20 different elements, using 120 standards developed at Metalor. Still, this approach is much more affordable than those used in the past, involving very expensive MC-ICP-MS or LA-ICP-MS, which are reserved for further investigations. Indeed, if, through our statistical approach, a doré bar is determined to be non-compliant, we rely on other investigations to understand this non-compliance.
- The immediate validation of the declared origin of a doré can be achieved on arrival at the refinery. With the GeoForensic Passport in hand, every doré received at the refinery is systematically analysed and tested to understand if it is compliant or not – that is, if its declaration of origin can be validated or not. In most of the cases, this validation is straightforward, but if the assignation is not clear or is only partially clear, further analysis is used. The more data available for any given customer, the more stable the system. This means that after a couple of months of data gathering from any given mine, the need to use additional analysis becomes less frequent.
Find out more
You can find out more about the origin of modern gold, archaeometry and other research conducted by the Faculty of Geosciences and Environment at the University of Lausanne, Switzerland, on its website: https://gold-dna.ch/