Mineralogical and microtextural parameters in metals ores traceability studies

• Statistical tests are used to compare the chemical composition of the target minerals
• Traceability implies that, for each province and deposit, valuable minerals have a unique signature
• Establishing an ore identity card would help to control trade in the mineral industry
• We have established an original traceability method for base metals
• This method has contributed to discriminate the bulk ores from different deposits and provinces

The demand in mineral resources is increasing rapidly, but there is a lack of transparency in the trade of concentrated raw mineral materials because of speculation and involvement in the finance of armed conflicts. Because of the distance between primary extraction and the final production sites it is difficult to check the origin of these products. An identity card is required for mineral commodities, so that trading in the industry can be verified and the traceability of concentrates ensured. This problem may be considered as an inversion process: studying the products sold to identify the original ore. The discriminant parameters are mineralogical composition, identification of textural microfacies of the target minerals, “pseudo-paragenetic sequence”, and the contents and distribution of minor elements of target minerals. For base metal, the selected target minerals are pyrite, for its ubiquity, sphalerite for its ability to host numerous discriminant and potentially valuable minor elements in its lattice and chalcopyrite for its proximity with the two other minerals. The Kolmogorov–Smirnov distance and the Colin–White test are used to compare the chemical composition of the three target minerals. The application to Volcanic Massive Sulfide ore deposits shows that it is possible to distinguish pyrite, sphalerite and chalcopyrite between two ore deposits in the Iberian Pyrite Belt province and seven ore deposits from the Urals province using the selected characteristics. Ore deposits from different provinces may be discriminated using the identity cards, as well as different deposits in the same province.