A good sauna stone has to accumulate heat, release it slowly and be heat resistant. For this purpose, dense and heavy stones are a good option. These grey rounded volcanic stones are known as olivine diabase and were collected in Finland. Olivine diabase is a very heavy stone with a density of approximately 3.5 kg/dm3. It is highly valued as a sauna stone for its durability and high heat capacity.
 
These are highly recommended for HUUM stoves to support both the visual design as well as the optimal sauna experience, but you are welcome to use your own stones that you collect or purchase from elsewhere. Please note that some types of stones are less effective in saunas, while some can even break and be dangerous. If you are unfammiliar with the right types of stones to be used in saunas then use a reputable supplier or get in touch with us at tere@estoniansaunas.com for advice.