Dunit – stone for baths and saunas

Natural stone is an invariable attribute of a Russian sauna with a stove. And just stones are often used in the decoration of the steam room. Today our site of advice will tell you about such an interesting stone as dunite, which will be an excellent choice for arranging a bath and sauna, as it has a number of positive characteristics.

Dunite was discovered for the first time in New Zealand, near the Dun Mountains. This is what became the reason for this name. Dunite is formed deep underground, below the earth’s crust, so it is absolutely safe from the point of view of the radiation background. Dunite belongs to ultrabasic stones, it contains from 30% to 45% silicon oxide, due to which the stone perfectly tolerates a large amount of heating and cooling, while not releasing toxic compounds.

The approximate chemical composition of dunite looks like this:

• MgO – about 38-50%
• SiO₂ – 35-40%
• FeO – 3-6%
• Fe₂O₃ – 0.5-7%
• Al₂O₃ – up to 2.5%
• CaO – 0.5-1.5%
• Na₂O – up to 0.3%
• TO₂O – up to 0.25%

Dunite is a grainy stone. Most often, the granular structure is small, but it can be medium or even large. In color, the stone is not remarkable for anything special – gray, brownish, interspersed with green, black shades. If the stone contains inclusions of a metallic color, it means that it contains sulfur, and this is not good for use in a steam room – they will release harmful acids.

The main characteristics of dunite:

• Density 3.28 g / cm³
• Specific heat 0.7–0.9 kJ / kg · K
• Melting temperature over +1200 ° C
• Young’s modulus 0.89–1.95 · 10^five MPa
• Poisson’s ratio 0.16-0.40
• Shear modulus 0.476-0.706 · 10^five MPa
• Thermal conductivity 1.2–2.0 W / m · K
• Thermal diffusivity 7.2-8.6 m²/from

The characteristics of dunite allow it to be used as a refractory stone, for example, when lining a furnace in a bath.

Important! Dunite heats up quickly, conducts heat, but also cools down quickly. For this reason, and also because of its not very presentable appearance, it is usually used in heaters as the first layer of stones..

For heaters, dunite is sold in packs of 20 kilograms, the price is low – from 300 to 1000 rubles for such a volume, that is, from 15 rubles per kilogram. The downside is that there may be defective stones in the package, with cracks and inclusions of sulfur. Therefore, always ask for a certificate and buy stones from trusted manufacturers. In addition, after you open the package at home, review all stones to remove those that crumble or have metal inclusions, indicating the presence of sulfur..

The benefits of using dunite in baths and saunas include:

• Low price.
• Ability to withstand very high temperatures without cracking.
• No smell when heated.
• Heating occurs quickly, the stone gives off heat evenly.
• Protects against poisoning by interacting with carbon dioxide.
• It has a beneficial effect on the musculoskeletal system, strengthens the nervous system, and has a good effect on the condition of hair and skin.

There are also disadvantages of dunite in the bath:

• Serves only 6 years.
• Seemingly not very pretty, ordinary cobblestone.
• There is a risk to buy a fake or a stone of low quality, with cracks and inclusions of sulfur.

Dunite “colleagues” that can replace it in stoves or be used together with it are talcochlorite, porphyrite, gabbro, raspberry quartzite, jadeite. By the way, the portal described in detail how to make a metal frame for a heater with your own hands.