Soapstone is a natural material with many different types as regards composition and structure. They all share one thing in common, which is their high content in talc, which makes them a soft natural stone. The Mammutti soapstone types of NunnaUuni’s own deposit are primarily made of half talc and half magnesite. Talc has become schistose and foliated under intense pressure while becoming stratified with fine-grained magnesite. Magnesite converts to periclase (MgO) at temperatures exceeding 520 °C.
A soapstone type including fine-grained magnesite has been selected for the NunnaUuni fire chamber. Periclase formed on the surface and the soapstone’s talc are sintered together in the extreme heat of the fire chamber creating an extremely hard surface. This surface withstands decades of use and enables rapid storage of heat. NunnaUuni fire chambers are fully lined with soapstone and do not require insulating protective plates or cast structures.