The burning mountain
The phenomenon is explained by the slow, continuous underground combustion of the pyritic shale beneath the surface: damp air seeps through cracks in the rock and sustains a reaction that has been going on for centuries. The vapours rising from it reach 120°C deep down, then cool naturally to 42°C by the time they reach the treatment cabins. Free guided tours of the boreholes, in the area known as the "smoking mountain", are offered in the afternoon for groups of 10 to 60 people.
From spa to mines, and back to spa
Cransac has been a spa destination since the 19th century, when it drew nearly 5,000 visitors taking the cure each year. The coal boom then tipped the village into the mining era, under the name Cransac-les-Mines, until the mines closed in 1963. The spa later regained the upper hand, and the current establishment, run in its modern form by the Chaîne Thermale du Soleil since 2003, specialises in treating rheumatism and neck and lower back pain. On-site accommodation, the Logis des Boisements, welcomes spa guests, and a museum on site traces the village's history through its three main periods.
Practical information
Allow about 25 minutes by car from the cottage, for just over 23 km. Borehole tours are for groups only, in the afternoon; check dates directly with the spa. Outside the cure season, the village also offers occasional workshops (herbalism in particular) and farmers' markets. La Découverte in Decazeville, with its headframe and lake, is only about ten minutes' drive away: the two visits combine well on the same day.