All gypsum deposits are of three types:
- syngenetic (rocks and gypsum included in them were formed simultaneously)
- epigenetic (the result of the hydration of anhydrite under the influence of groundwater).
In the first deposits, gypsum deposits are in the form of lenses and formations with a thickness of up to 20 m or more.
In the deposits of the second type - reservoirs complicated by internal tectonics, folding, blowing and pinching.
The gypsum deposits in Russia are almost always sedimentary.
The residual (gypsum accumulation during leaching of minerals in salt deposits) and metasomatic (gypsum substitution of carbonate rocks under the influence of sulfate waters) type of deposits is practically not found in the Russian gypsum industry.
From the point of view of geology, the gypsum deposits of Russia used by industry are located in the sedimentary layers of the Cambrian, Devonian, Carboniferous, Permian, Jurassic and Quaternary periods. The Carboniferous period accounts for more than 55% of reserves, then Permian (32%) and Devonian (10%).
According to an estimate made in 2003, the state balance of gypsum reserves is 3,275.9 million tons. Of the fields considered in the calculation, 24 are being developed, which is 28%.
As can be seen from the table, the main (more than half) of the gypsum reserves are concentrated in the Central Federal District, where the 6 largest deposits are located. Significant reserves of gypsum raw materials are also possessed by the Volga and Southern Federal Districts (in total - one third of the country's reserves).
In total, there are 86 gypsum deposits in Russia, most of which have small reserves. 90% of gypsum produced is accounted for by 19 major deposits with reserves of more than 25 million tons.
The nine largest deposits of Russia (over 100 million tons): Novomoskovskoye, Pavlovskoye, Skuratovskoye, Bolokhovskoye, Pletnevskoye, Baskunchakskoye, Lazinskoye, Poretskoye and Obolenskoye. They account for 75% of all production. Most deposits contain a mixture of gypsum (up to 90% usually prevails) and anhydrite.
For comparison, the world's proven gypsum reserves amount to more than 7,500 million tons. That is, half of the world's reserves are located in Russia. At the same time, the production of gypsum raw materials in the world is about 110 million tons per year, and in Russia - about 6 million tons, that is 5-6% of world production. Russian gypsum reserves will significantly increase production in the future.