Pizarras y metacuarcitas como pavimentos de exteriores: las rocas de Bernardos (Provincia de Segovia)

Abstract

The slates and metaquartzites of Bernardos (N of the Sierra of the Guadarrama) are studied as ornamental rocks. A detail characterisation of the mineralógicaI, petrological and petrophysics properties was realised. These metamorphic rocks consist of quartz, plagioclase, muscovite, clorite and biotite, and often the ilmenite is an abundant accessory mineral. The influence of the anisotropy on the physical properties is evaluated. In particular, the hydric behaviour and the abrasion and slip resistance show a pronounced directional dependence produce by the rock fabric. The physical properties of the marketed rocks depend strongly on direction of the cutting and type of finished. Thus, the types of commercial stones with the slab surface parallel to the cleavage plane (Pizarras de Bernardos) and to bedding plane (Cuarcita Segovia) present adequate properties as paving. On the other hand, the types of commercial stones, in which the direction of the cutting is non-parallel to rock structure, present excellent aesthetic properties. The commercial name of this kind of rocks is "Filita" (Filita Gris Cordillera) and is appropriated as cladding.