Soungari Jean Paul YEO^1,, Zié OUATTARA², Wilfried DIGBEU², Ismaïla OUATTARA¹, Abou Junior DIABY², Ismaël SYLLA¹, Bamory KAMAGATE³

Artisanal mining is spreading inexorably throughout Côte d’Ivoire, particularly in the western part of the country, with certain socio-environmental risks affecting both the gold miners and the populations living near mining sites. Gold is often associated with other metals and metalloids such as arsenic and lead, which are toxic to animals and humans. These toxic elements, released during mining activities, are dispersed into water and soil, while a significant proportion remains trapped in the huge amounts of waste produced and dumped into the environment. In western Côte d’Ivoire, which has become a zone of intense artisanal gold mining activity, the consequences of the activity are little studied. Indeed, the solid mining residues from this activity have not yet been the subject of a dedicated study. The present study is conducted based on observations, macroscopic and microscopic descriptions, and geochemical analyses. Microscopic studies using transmitted and reflected light revealed that the rocks from the mining sites are volcanosedimentary formations (schists and micaschists). The observed outcrops are metamorphic rocks, mostly metagranites, mica granulites, as well as granites and microgranites. These rocks are mainly composed of quartz, micas, feldspars, amphibole, and accessory minerals such as chlorite, epidote, and sericite. There is also a notable abundance of sulfides, including pyrite, chalcopyrite, pyrrhotite, arsenopyrite, and magnetite in the rocky waste, whose oxidation can lead to acid mine drainage. Geochemical analysis also highlights the effects of sulfide oxidation in the form of enrichment of residues in Cadmium, Cobalt, Chromium, Copper, Manganese, Nickel, and Palladium compared to the average concentrations of the Upper Continental Crust (UCC) or Clarke values. The trace metal elements identified in this study are specific to the geological and geochemical context of the studied area.

Metals and metalloids, artisanal mining activity, mining solid residues, Western Côte d'Ivoire