Monte Calvo, Hill in the province of Grosseto, Tuscany, Italy

Monte Calvo is a hill with a north-south ridge reaching 467 metres above sea level, located between Gavorrano and the hamlet of Ravi in the province of Grosseto. Its eastern slopes, steep and rocky, drop towards Ravi, while the western slopes overlook the Pecora river plain. The summit area is bare, covered by dry grasslands of Helichrysum italicum and Satureja montana.

Monte Calvo is a north-south ridge of massive Lower Jurassic limestone of the Tuscan Nappe, reaching 467 m, distinct from the sandstone Monte d'Alma it joins to the south. Its eastern slopes above Ravi show karst caves, sinkholes and deep rock fractures, and the contact with the Chianti macigno follows the Fosso dei Crognoli. The northern part is now quarried for limestone, while the Ravi area was once mined for pyrite, as at the Miniera Marchi.

The mountain's name, "Calvo" (bare), refers to its denuded summit, where dry grasslands of Helichrysum italicum and Satureja montana replace the surrounding scrub. In late May the giant umbellifer Ferula glauca, over two metres tall, opens broad yellow umbels on the rocky slopes above Ravi, a sight noted in the regional flora lists.

The summit ridge runs north-south at 467 m, with steep, rocky eastern slopes above Ravi and equally steep western slopes facing the Pecora plain between Scarlino and Gavorrano. The limestone bedrock lets almost no water stay on the surface, and the only stream, the Fosso dei Crognoli, is dry most of the year. The northern part is affected by limestone quarrying.

The eastern slopes above Ravi are dotted with karst features — caves, sinkholes and deep fissures in the limestone — and surface water is almost entirely absent because the rock is so permeable. The only stream, the Fosso dei Crognoli, is dry for most of the year despite lying in a wooded, sunken bed.