Caracterización mineralógica del Caolín de Golpejas (Salamanca)

Abstract

In the present work, we propose a systematics of mineralogical characterization through field spectrometry VNIR- SWIR (visible, near-infrared and short-wave infrared) as well as the techniques most used for the identification and semi- quantification of special clays. The basis of the mineralogical study has been X-ray diffraction, according to the classical rou- tine of studies on clay minerals. As a case of study, the tin deposit of Golpejas (Salamanca) has been selected. The Golpejas tin deposit consists of several sheets of albite microgranite, more or less circular in shape, that intersect the metasediments of the schist-graywacke complex in the Iberian Zone. The emplazament took place during the extensional phase of Variscan Orogeny and the processes of greaseization and hydrothermal kaolinitization increased the concentration of Sn, Nb, Ta as well as kaolin. The albite leucogranite carrying the mineralization show a strong kaolinitization that occurred during the final phase of the mineralizing stage. As kaolinite group minerals (kaolinite, dickite and nacrite) have characteristic and differentiating features in the range of wavelenght studied with the proposed technique (VNIR-SWIR), the spectra obtained together with the classic clay mineral study techniques, allow us the mineralogical characterization of the Golpejas kaolin.