NunnaUuni is the maker of soapstone wood stoves and has incorporated the century old technique for heat retention. The company, based in Finland has used periclase on the surface of the fire chamber which makes sure that the thermal properties remain strong.
Periclase can withstand temperatures up to 1600 centigrade and a melting point which is close to 2800 centigrade. When compared to talc, it is 6 times harder and the magnesium carbonate in the soapstone helps produce great heat which lasts longer as well. The structural design of NunnaUunni stoves requires heating of only 2 -3 hours to give steady and prolonged heat, for about 24 hours.
Heat from the NunnaUuni stove encompasses the house like the sunrays and envelops all with its warmth. The advantage of a soapstone fireplace is that the heat from it warms all surfaces it touches and not only the air inside the house. You can compare it to the effect of the sun in the open air.