the chemical, physicochemical, biochemical, and microbiological methods of extracting minerals from the places where they are deposited. The mining of minerals by geotechnological methods is usually conducted through boreholes drilled from the surface to the locality. Examples of geotechnology are underground coal gasification, bacterial lixiviation, sulfur liquefaction, sublimation of substances, the extraction of mineral products from thermal waters and volcanic deposits, and the thermal extraction of petroleum and its distillation products. About two-thirds of the world’s sulfur is produced by underground liquefactions of ore bodies using superheated water, which results in high quality (99.99 percent pure). The method can be used to mine asphalt, borax, ozokerite, and other minerals that melt at 80°-90° C. Potassium salts can be mined by dissolving them, with subsequent pumping of the solution and evaporation aboveground.

Industrial experiments on the acceleration of extraction of metals from ores, increasing stratum pressure at petroleum-bearing localities, and so on by artificial stimulation of microbiological activity are being carried out (1971). Geotechnology makes possible the exploitation of localities with noncommercial ore contents and a broadening of the mining of trace elements.