The chrysotile of asbestos occurrencesin the Mellid area, NW Spain

This paper is based on field data collected during a basic survey of mining exploration carried out by the authors for the Instituto Geologico y Minero de España. The investigated area belongs to the southeastern part of the Ordenes Complex and is mainly composed of metabasites and ultramafic rocks. Inside the area, three great ultramafic bodies can be mainly considered. They are more or less parallel and trend in a NNE direction, being separated by zoisite-bearing amphibolites. Asbestos showings are numerous in the eastern ultramafic body, which forms the Careon range, the length of the fibra ranging up to 14 mm. Only two minor asbestos occurrences have been found in the central body, and, finally, a few asbestos veinlets have been seen in the western ultramafic body, with fibres not reaching 1 mm in length. Chrysotile asbestos mineralization in the area always belongs to the ‘cross-fibre’ type. Brief descriptions of asbestos occurrences and geological framework are made, and hypotheses about asbestos genesis in the area are finally set up.