Identifying the source of illicit gold from South America

Abstract

Illicit trade in gold, mainly sourced from South America and Africa, is used to fund criminal activities such as the drug trade. Laundering money through the purchase of illicit gold, then having it refined and being paid for in clean funds is a major problem, and drives further growth in illicit mining. In order to restrict the influx of illicit gold into the legal domain, it is necessary to be able to identify the traded item as being of a licit or illicit nature. The only way that this can be done with any certainty is by determining, from its chemical composition, the source of the gold and the means by which it has been processed and upgraded. The example dealt with here shows how the use of compositional, processing and geological knowledge is able to discriminate gold from different origins. Data derived from a physical sample is far better able to constrain the source than a paper trail of certification, which can be manipulated.

Challenging the traceability of natural gold by combining geochemical methods: French Guiana example

“…in the grain core). Trace element profiling of gold, which is the most common technique, has been used to help distinguish legal from illegal gold (Roberts et al, 2016) and to identify the source of the latter (Watling et al, 1994(Watling et al, , 2014Dixon and Merkle, 2019). The technique consists of quantifying the trace-level components within gold matrices by laser ablation inductively coupled plasma mass spectrometer (LA-ICP-MS) and is mainly based on the assertion that gold will inherit a unique trace element signature related to specific geological (e.g.…”

“…Deciphering gold fingerprints using trace elements is increasingly used in ore deposit studies (Banks et al, 2018;Chapman et al, 2021; and is the most common technique for identifying the source of illicit gold (Watling et al 1994(Watling et al , 2014Dixon and Merkle, 2019). However, in previous traceability studies this technique is only applied to raw spectral data without any calibration or standardization with matrix-matched reference materials.…”

“…But even the most advanced analytical methods will not resolve the uncertainty for samples with the same geological origin and related genetic processes. Keep in mind that seized gold is never entirely unknown and that determining its origin follows a forensic investigation that depends on the context of the seizure, the persons involved and the links to previous cases, and is therefore but one part of the information that helps trace the origin of the gold (Dixon and Merkle, 2019). Like the use of minor components or mineral inclusions, the trace elements fingerprint may help to go further into sample discrimination, but cannot substitute the KS method applied to the Ag content to trace and certify gold provenance within traceability framework.…”

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“…A disponibilidade de equipamentos analíticos e a simplificação dos procedimentos analíticos aumentaram significativamente a utilização de parâmetros químicos para se identificar a origem de minerais (Dixon and Merkle, 2019;Gäbler et al, 2013;Melcher et al, 2008), metais nobres (Dixon and Schouwstra, 2017;Dixon and Merkle, 2019;Roberts et al, 2016;Watling et al) e mesmo drogas ilícitas (Watling, 1998).…”

“…Mais recentemente duas publicações abordam a utilização de elementos-traço e isótopos para identificar ouro ilícito (Dixon and Merkle, 2019;Roberts et al, 2016). Robert e colaboradores desenvolvem um trabalho sobre a distinção entre ouro legal e ilegal na África do Sul.…”