The "Macigno" sandstones from Matraia and Pian di Lanzola quarries (north-western Tuscany, Italy). A comparison of physical and mechanical properties

Within the framework of a research program devoted to quantify the natural stones quarried in the Garfagnana and Lunigiana areas (north-western Tuscany, Italy) in terms of quality, a careful study of the «Pietra di Matraia» and «Pietra di Pian di Lanzola» with respect to physical and mechanical properties was performed according to European Standards/Norms indications. The studied stones have been locally employed as building materials and as decorative stones from prehistoric times until today. They belong to the Macigno Formation (Upper Oligocene to Lower Miocene) that crops out extensively in the Northern Apennines and consists of grey to bluish-grey, well-consolidated, fine- to medium-grained, poorly to moderately sorted siliciclastic sandstones, with quartz, feldspar and micas. «Pietra di Matraia» and «Pietra di Pian di Lanzola» are to be regarded as heavy and compact arenitic arkoses, characterized by both low values of porosity and water absorptions at atmospheric pressure, unaffected by freeze-thaw cycles, with an high strength for compression, flexure and impact stress. Sandstones from the Matraia quarry show lower values of porosity and water absorption as well as a significantly higher value of flexural strength under concentrated load than those obtained on «Pietra di Pian di Lanzola» samples.