Geological Prospecting

the totality of operations involved in discovering deposits of useful minerals. Geological prospecting is carried out on the basis of a study of the geological structure of the terrain together with geological mapping. Sometimes it is based on data from earlier geological surveying. As a scientific endeavor, geological prospecting depends on maps of the probable distribution of useful minerals in the territories under investigation or reconnaissance maps that predict the location of useful minerals. Prospectors take into account the conditions under which deposits of useful minerals are formed or the genesis that is manifested by the association of certain minerals with certain elements of the geological structure of the terrain. The use of these elements in searching for deposits of useful minerals requires a knowledge of what are called prospecting indicators. These include characteristics of the deposits’ link with elements of the local stratigraphy, lithology, tectonics, petrography, geochemistry, and geomorphology.

The types of special field and laboratory investigations that are made during prospecting depend on such geological conditions as the degree of exposure of bedrock, the thickness of the cover of loose deposits, and the relief of the terrain.

In surface geological and mineralogical exploration, the river-detritus, glacial-boulder, and concentrate methods are used. In areas covered by loose anthropogenic deposits, the regularities in the location of glacial boulders, river gravel, and slope talus are studied, the useful minerals located among them are determined, and the distribution of these minerals is characterized. Washing of river sands or loose deposits on slopes may yield valuable minerals, such as gold, platinum, tin ore, wolframite, and diamonds, which are found in the heavy fraction (concentrate) of these deposits. Tracing the a real distribution of valuable minerals in concentrates leads to discovery of placer and primary deposits of useful minerals. Shallow mining operations, such as the digging of test pits, trenches, and holes, are usually performed during geological prospecting. In places where theoretical considerations indicate the presence of buried deposits that do not reach the surface, geological prospecting involves drilling exploratory boreholes and, sometimes, digging deep shafts and adits.

Geochemical exploration includes metallometric, hydro-chemical, biogeochemical, and geobotanical surveying, as well as the analysis of gases and emanations.

Geophysical exploration is based on the use of differences in a number of physical properties between bodies of useful minerals and the enclosing rock. Differences in elasticity, magnetism, electrical conductivity, density, and radioactivity are tested. Airplanes, helicopters, and artificial satellites are used extensively in geophysical prospecting.