The Biancane nature park is a natural area near the center of Monterotondo Marittimo (GR) where the " biancane " characteristics are located, representing one of the many sites where geothermal energy strongly characterizes the landscape on the border between the provinces of Pisa and Grosseto . In fact, there are several types of geothermal manifestations such as showerheads, steam spills from the ground, putizze and fumaroles .
The steam that comes out of the fractures of the rocks has a temperature of about 100 ° C and consists of 95% of water vapor and the remainder of carbon dioxide , methane , ammonia , hydrogen sulphide responsible for the characteristic smell of rotten eggs, boric acid , nitrogen , hydrogen and to a lesser extent helium , argon , radon and other noble gases .
At the steam outlets there are crystals of native sulfur in the form of acicular aggregates or encrustations due to the oxidation of hydrogen sulphide due to contact with air. The presence of hydrogen sulphide also causes an intense acidification of the soil and the strong chemical aggressiveness of some components of geothermal fluids has produced an evident whitening of the soil.
All the rocks are altered by the circulation of geothermal fluids, alterations that occur with the disappearance of the original colors and with variation of the composition.
The Biancane with its Lagoni represent one of the areas of competence of the Archaeological Technological Park of the Grossetane Metalliferous Hills .