Dunite - volcanic rock

Organic
Dunite is an intrusive ultramafic igneous rock. It is an extremely environmentally friendly stone that does not contain harmful impurities and does not emit toxic substances when heated. It has high refractory properties, due to which it can be used for a long time. In the Urals, dunit has traditionally been considered one of the best stones for a bath.

History and origin

The dunite stone gets its name from the New Zealand mountain Dun, where it was discovered.

Being a deep igneous rock, dunite is formed at the initial stages of lava differentiation, when olivine and, in some cases, chromite crystallize from the melt. Settling at the bottom of the magma chamber, the mineral forms an almost monomineral rock.

mineral

The main component of dunite is olivine - it consists of 85-90% of it, which determines the color of the stone, which varies from dark gray to almost black and from yellowish green to dark green.

Under the influence of weathering, olivine, which is part of this rock, is converted into serpentine and partially into magnetite. Dunite is rarely found unaltered, usually being largely serpentinized or even completely serpentine. Also, chromium and magnetic iron ore are often found in dunite.

Usually dunite is found in the lower layered horizon of the main intrusions.

Mining

Being an ultrabasic igneous rock, dunite is commonly found in the mountains of the Urals and the Caucasus, as well as in the Baikal region, but its extraction is associated with certain difficulties. The Kytlymsky dunite deposit located in the north of the Middle Urals is widely known.

Reference! Outside of Russia, the main deposit of this rock is Dunite Mountain in New Zealand; dunite is also found in Kazakhstan and Central Asia.

Physicochemical characteristics

Dunite is characterized by a full-crystalline fine- or medium-grained structure, as well as a massive rock texture and high density. It is a mixture of olivine (up to 90%) with pyroxenes, amphibole and chromite. Also, this rock is extremely rich in magnesium and contains a very small amount of silica.

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Property Description
Density 3,28 g / cm³
Specific weight 3
Texture massive
  Structure Medium or fine grained
Radiance No
Mixing Pyroxene, amphibole, olivine and biotite
Transparency Opaque
Color in daylight Light green to black

Average chemical composition:

  • SiO2 35-40%,
  • MgO 38-50%,
  • FeO 3-6%,
  • Al2O3 up to 2.5%,
  • CaO up to 1.5%,
  • Fe2O3 0.5-7%,
  • Na2O to 0.3%,
  • К2About up to 0.25%,
  • TIO2 up to 0.02 %.

Stone types

In industrial mineralogy, the following types of dunite are distinguished:

  • chromite - containing chromite (iron and chromium oxide) up to 30%;
  • ilmenite - containing ilmenite (titanium iron ore) up to 36% and 4% of accessory minerals;
  • magnetite - containing titanomagnetite up to 30%.

Each variety has its own practical application.

Scope of the mineral

Dunite is widely used in the construction of baths and saunas to fill stoves and heaters:

  • low coefficient of linear expansion protects stones from cracking during repeated heating and cooling, as well as when exposed to hot water;
  • due to the granular structure, the stone has a unique heat capacity and at the same time increased thermal conductivity, which allows you to quickly heat the heater to the desired temperature and retain heat for a long time.

Interesting! The stone can withstand heating temperatures up to 1700 ° C, so it is used for metal casting.

Dunite is also used:

  • as a refractory material in metallurgical furnaces due to its refractory properties (a magnetite variety is used);
  • as a building material for refractory structures;
  • for the manufacture of heat-insulating inserts in the steel industry;
  • in the production of heat-resistant ceramics (the ilmenite variety is used);
  • for the manufacture of high-quality cladding materials for bathrooms, swimming pools, etc.;
  • for flooring - such floors do not slip and maintain a comfortable temperature in any weather;
  • as an ornamental stone;
  • when creating cement mixtures to increase the impact resistance of cement stone and concrete;
  • in agriculture to increase fertility; is the best source of microelements when growing potatoes (magnetite variety is used).
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Price

Dunite is a relatively inexpensive stone. Its price on the market is from 0.3 to 0.6 euros per 1 kg. Dunite for baths is usually sold processed and packaged in boxes of 20 kg, which ensures ease of transportation.

stones

Important! Do not chase the price, because there is a risk of running into a fake that releases sulfur when heated, resulting in the formation of sulfuric acid, which can be harmful to health.

Also, under the guise of dunite, pyroxenite is often sold, which is easier to mine, because its cost is lower, but it can crack under the influence of high temperatures and release toxic substances.

Medicinal properties

Useful properties of dunite for use in the bath are based on the presence of olivine in it (which is much more in dunite than in another widely used bath stone - dolerite), which has pronounced healing properties.

Bath procedures with dunite:

  • normalize cardiac activity;
  • reduce blood pressure;
  • increase immunity;
  • strengthen the nervous system;
  • help with colds;
  • used for eye diseases;
  • used for diseases of the musculoskeletal system;
  • disinfect problematic skin;
  • increase libido in men.

Specialists of the Institute of Mineralogy gave the highest rating to dunite as a stone for use in baths and saunas.

Dunite is a natural air purifier with a unique property: when heated in a bath, this stone reacts with carbon dioxide and thus purifies the atmosphere in the room, eliminating the appearance of extraneous odors.

dunite

Interesting about the stone

  1. The best variety of dunite for use in the bath is Ural. The stone should be laid on the bottom of the furnace under layers of other stones used for therapeutic purposes. This increases the overall healing effect, since dunite heats up quickly and retains heat for a long time. Use with white quartz and Himalayan salt promotes air ionization and creates a cozy microclimate in the home bath.
  2. The thermal stability of dunite is due to the low content of volatile substances in the composition. When calcined, the stone can only lose 1,5% of its mass, so it does not crack.
  3. Dunite can be ground into sand fairly easily. In this case, olivine grains take on the role of grains of sand.
  4. In the past, mineralogists believed that dunite might contain diamonds and platinum. There is unconfirmed evidence that such single finds have taken place, but over the past decades, despite intensive searches, such a breed has not been found.
  5. A separate advantage of the stone is its beautiful and unusual texture. Dunite has a huge number of shades and contains a variety of decorative inclusions, which naturally finds application in design.
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Due to its unique properties, dunit stone is widely used in industry, agriculture, and even in interior design. And the exceptional heat resistance and environmental friendliness, combined with the ability to have a healing effect, make dunite indispensable for use in baths and saunas.

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