Abstract. As construction and building material, natural stone has a great potential to promote the commercial activities of certain European regions. Such is the case of Castilla y León in Spain, where many different rocks, ranging from sedimentary to metamorphic and igneous, are commercialized for building purposes. However, to be able to compete in a market subject to an economic crisis, highly exacerbated in the construction sector, and to compete with the lower prices offered by emerging countries, the issue would be to make the Spanish offer more attractive. Here we propose a complete characterization of rocks regarding their radiological properties, which are related to their mineralogy and geochemistry. Rocks emit natural radioactivity, and the presence of Rn and its decay products in dwellings has become an important issue in North America and Europe owing to its relationship with the carcinogenic effects of this gas. Although most of the studied rocks comply with the I parameter proposed in the European Norm 112 for Radiological Protection (accepted value I ≤ 1; average for sedimentary rock: I = 0.22, SD 0.14; average for metamorphic rocks: I = 0.70, SD 0.48; average for igneous rock: I = 0.86, SD 0.22), the inclusion of a proper radiological characterization in the list of characteristics would guarantee quality and safety in their use in comparison with products lacking this information. Some natural stones have been demonized for the potential exhalation of natural radioactivity, and the different parameters used should be addressed in a more systematic way.