Mineralogical Composition and Structure of Fibrous Anthophyllite: A Case Study from Argentina

In this work a multimethodological approach is taken, complementing field studies with petrographic-mineralogical, compositional and morphological analyses of anthophyllite in the “Coco Solo” mine from the province of Córdoba (Argentina). Fibrous minerals were studied by stereomicroscopy, polarizing light microscopy and SEM. The fibres have positive elongation, straight extinction and slight pleochroism. Thermogravimetric and differential scanning calorimetry (TG/DSC) data allowed the determination of the structural water content and temperature stability. X-ray diffraction was used for the characterization of the mineral fibres before and after heating at 1000 °C to identify the products of thermal decomposition. The crystal structure determined corresponds to anthophyllite. Finally, morphological analyses on acicular and fibrous phases were conducted. Particles up to ~1 µm were analysed by optical microscopy, while particles up to ~0.1 µm were examined by SEM. When complemented, these two techniques are useful to characterize the morphologies of the particles.