Key facts

Concept

Pale grey unhomogeneous sandstone with fine grain.
Not a very porous rock, the interstices between the granules are almost completely occupied by carbonatic concrete.
The very rich carbonatic component is formed by algal fragments, foraminifera shells, bryozoa, plates of echinoderms and by a component of micro crystalline calcite, by nature, crystallized also inside the foraminifera shells. Less frequent are quartz, feldspars and fragments of magmatic and metamorphic rocks, and flint.