Características petrográfico-mineralógicas de la alteración de basaltos de la
Meseta de Somón Curá, prov. de Río Negro
The mineralogical charactenstics of basalts from the northem of the Macizo of Somuncura (Río Negro Province) were studied. The objet of this paper is to assess the alteration grade, especiaily the presence of montmorillonite and volcanicglass. These materials provoke the degradation of the portland cement concrete when they are present in the aggregates, causing damage and some times fractures.