Abstract

LESCANO, Leticia et al. Minerales asbestiformes en vermiculitas del sector centro-occidental de la provincia de Córdoba. Rev. Asoc. Geol. Argent. [online]. 2015, vol.72, n.3, pp.378-384. ISSN 0004-4822.

Two vermiculite mines of the province of Córdoba were studied: Mauro and La Isla. Mauro (32º16'39,6" S y 64º52'15" W) is located in the eastern flank of the cerro Negro in the sierra de Comechingones, 60 km west of La Cruz in the Calamuchita valley, and La Isla (31º49’30,6” S y 64º24’53” W), located in the eastern flank of the Sierra Chica, 2.5 km south of José de la Quintana in the department of Santa María. The western and central areas of the cerro Negro are constituted by serpentinites with several alteration degrees, cut by veins rich in asbestiform minerals. Where serpentinite is intruded by pegmatites, vermiculite halos are developed associated with fibrous minerals, which are object of mining work. The easter zone of the intrusive body is constituted by coarse-grained, fractured and hydrothermally altered amphibolite with tremolite associated. The mining works developed in La Isla, allowed to observe ultramafic bodies altered to talc, associated to amphibolites, intruded by granitoid dikes and pegmatites. In the contact zone between the intrusives and the ultramafic body, zones rich in vermiculite and amphibole, and veins with asbestiforms fibrous minerals have been generated. Studies with optical microscopy, scanning electron microscopy and X-ray diffraction were performed in order to characterize the present minerals. Anthophyllite, acicular, splintery and asbestiform amphiboles distributed in veins associated with vermiculite and tremolite-ferroactinolite in the mineralized rock were identified. The presence of these minerals in the studied mines is considered an alert to intensify the environmental controls if their exploitation were activated.

Keywords : Tremolite-ferroactinolite; Serpentinite; Anthophyllite.