Warm Stone is a local heating device, inspired form the Berger Lamp system, and meant to be used on a coffee terrace during winter. It is made of steatite, a soft stone from Brazil with great thermal properties.
The brass body receives the fuel. To turn the lamp on, the catalytic burner needs to burn for a couple of minutes in order to reach the right temperature. The flame can then be blown and the stone placed on the top. The burner will keep on burning without any flame as long as there is some combustible left. A brass lid placed over the perforations will block the oxygen and turn the heat lamp off.
Once it has been heated up, the stone gently radiates the heat and remains warm for approximatly one hour due to its high thermal inertia.