Tulikivi's fireplaces are made from Finnish soapstone. Soapstone withstands high temperatures, stores the heat and then gradually releases it. Anything that can be cooked in a conventional oven can be cooked in a Tulikivi. The added plus of a Tulikivi is that a meal cooks while the fireplace generates heat for the house. This oven generates enough heat to warm an 850 square-foot area.