ABSTRACT
Hot spring deposits form where minerals, chiefly mercury and gold, precipitate as the thermal spring water cools. Modern prospectors use geophysical techniques, geochemical surveys, and remote sensing to locate indicators of mineralization. Indicators of mineralization include bleaching caused by mineralizing fluids that alter feldspars to clay, and the weathering of pyrite that turns the landscape red. "Energy minerals" include uranium and coal. Uranium is used primarily to generate heat to run turbines in electrical power plants. The most important uranium minerals are the oxides uraninite and pitchblende. Uranium minerals, soluble in oxygen-rich groundwater, precipitate at the contact with a reducing environment. Metamorphic uranium deposits occur in metasediments and metavolcanics. Common rare earth minerals include apatite, fluorite, monazite, and zircon. Rare earth minerals are usually found in alkaline igneous rocks, that is, rocks with more alkali metals than silica. Calcium carbonate, in the form of limestone, is a common industrial mineral.
