Mineralogical characterization of the polymetallic mineralized body of the Bajo de Limón Mine (Mora canton, Costa Rica)
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| Autores: | , , , , , , , , , |
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| Format: | artículo original |
| Status: | Versión publicada |
| Fecha de Publicación: | 2026 |
| Beskrivelse: | In Costa Rica there are various historical records about the mining activity developed between the end of the 19th century and the first half of the 20th century in the Central Valley, although none of them delve into the systematic characterization of the polymetallic structures located in the canton of Mora (San José province). This study presents the mineralogical characterization and genetic interpretation of the polymetallic veins of the inactive Bajo de Limón mine (Piedras Negras district, Mora canton), hosted in sandstones and shales of the Peña Negra formation (middle Miocene). The main vein is accessible via a tunnel approximately 189 m in length that cuts through at the groundwater level. Field observations, petrography (transmitted and reflected light), X-ray powder diffraction (XRD), and scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM–EDX) were integrated and complemented by physicochemical assays of drip waters and internal pools. Twenty-five mineral phases were identified, including primary sulfides (galena and sphalerite) and silicate–carbonate gangue minerals (α-quartz, muscovite/sericite, epidote–zoisite–clinozoisite, and calcite), as well as supergene minerals formed by oxidation and secondary precipitation processes (anglesite, cerussite, brochantite, malachite, azurite, goethite, gypsum, and clays). Mineral associations and textures indicate an evolutionary sequence from a hydrothermal stage, characterized by sericitic–propylitic alteration, to supergene oxidizing conditions. Waters exhibit slightly alkaline pH values and are dominated by calcium–magnesium bicarbonate facies, with a relative increase in SO₄²⁻ concentrations in internal pools, consistent with water–rock interaction and sulfide oxidation processes. Overall, the available evidence indicates a polymetallic hydrothermal system subsequently overprinted by supergene processes, whose genesis may be related either to a deposit within the VMS-SEDEX spectrum or to a Cordilleran-type hydrothermal vein deposit. |
| País: | Portal de Revistas UCR |
| Institution: | Universidad de Costa Rica |
| Repositorio: | Portal de Revistas UCR |
| Sprog: | Español |
| OAI Identifier: | oai:portal.revistas.ucr.ac.cr:article/11273 |
| Online adgang: | https://revistas.ucr.ac.cr/index.php/rgeologica/article/view/11273 |
| Palabra clave: | Sulfides Hydrothermal alteration Supergene minerals SEM-EDX X-ray diffraction Sulfuros Alteración hidrotermal Minerales supergénicos Difracción de rayos X |