Pietra Serena Sandstone

Generale_Pietra Serena
Column in Pietra Serena Sandstone (Piazza Santissima Annunziata).

Lithotype

Pietra Serena Sandstone

Common names

Pietra Serena, Pietra Macigno, Pietra delle Colline di Fiesole, Pietra del Fossato, Pietra Bigia.

Rock classification

Sedimentary rock

Province of Florence: Fiesole, Monte Ceceri, Mugnone and Mensola Valleys, Gonfolina, Montebuoni, Greve.

This sandstone (turbiditic Macigno Formation) is dated to the Upper Oligocene – Lower Miocene. It is a quartz-feldspatic-micaceous sandstone in layers of different thickness (1- 5 meters) separated by thin levels of shales and siltites. The sandstone is classified as a lithic arcose.

Already employed in the Etruscan and Roman periods, it was used in Firenze mainly during the Renaissance, for flooring, stairways, square, columns, pilasters, cornices and other decorative architectural elements.

Prevailing silicate composition consisting of quartz, feldspar, micas; clay minerals are also present and, in small amounts, calcite.

Macroscopic description

Medium-coarse-grained sandstone, bluish-gray color when cut, it can become ocher for alteration. It is a hard, compact, non-polished, low-medium porosity rock.

Macroscopic aspect of a Pietra Serena Sandstone.
Macroscopic aspect of a Pietra Serena Sandstone.

Microscopic description

Clay-rich sandstone with a low content of calcitic cement. Clastic granules (medium-coarse grain) consist of quartz, feldspars, fragments of metamorphic and magmatic rocks, muscovite and biotite (often transformed into chlorite).

Thin section micrograph of a Pietra Serena Sandstone.