Mineralogy, geochemistry and origin of karst bauxite deposits from the Reserva Fiscal Ávila, SW Dominican Republic

Abstract

The energy transition requires growing amounts of critical metals. Among them, Rare-earth Elements and Yttrium (REY) are essential for renewable energy technologies. Karst bauxites have emerged as promising non-conventional REY sources, along with Sc and Ga. The Sierra de Bahoruco in SW Dominican Republic hosts the world's most REY-enriched karst bauxites. In response, the government designated the Reserva Fiscal Ávila (RFA) for resource assessment. This study provides the first mineralogical and geochemical data from the RFA bauxites, which include Al-oxyhydroxides, kaolinite, and Fe-oxyhydroxides. REY contents reach up to 2,542 ppm, with enrichment in light REE and Y. Correlations with Th and K suggest gamma-ray spectrometry as an effective exploration tool. The presence of Sc (up to 105 ppm) and Ga (up to 54 ppm) could add economic value beyond aluminum extraction.