ECONOMIC GEOLOGY 437 Variety and Use of Mineral Deposits The range of ‘geologic bodies and materials’ that is utilized by man has grown in scope and volume over the course of history, but falls into a few practical groups Construction Materials These include building stones, sand, aggregates, clay, and cement raw materials The high cost of transporting these bulk products requires source rocks to be as close as possible to the place of utilization, but typically the costs of extraction and treatment are low A long history of use (the stone walls of Jericho were packed with a clay mortar circa 8000 bc) has built a body of experience concerning desirable source materials and their properties In developed countries today, geological knowledge is applied to not only ensure that technical specifications are met, but also to discover and delineate those particular sources that best suit land development planning and minimize environmental problems Some industrial rock products are valuable enough for export, such as clays for ceramics and ornamental stone for decorative use in buildings Fuel or Energy Mineral Deposits These include hydrocarbon fluids, coal and uranium Coal is a sedimentary rock derived from plant remains, the fossil fuel on which modern industrial development was built Together with petroleum, this versatile material supplies most of the worlds’ energy needs It is also a major industrial raw material for the manufacture of chemicals, and coke for iron and steel production Economic deposits of uranium-bearing minerals, the base on which the atomic age is built, occur at a scale of magnitude nowhere near that of coal and oilfields Industrial Minerals Sometimes termed non-metallic minerals, these are valued for their chemical and/or physical properties and the fact that they are not of widespread occurrence In general, prices are sensitive to market demand and product specifications (with premium prices for premium grade products), and quality is a major factor in the economic geological evaluation of mineral reserves and productive life of industrial mineral deposits A vast range of industrial minerals is produced in an equally impressive range of tonnages Minerals with valuable chemical properties, used mainly in the chemical and fertilizer industries, include rock phosphate, potash and mixed chloride salts, sulphur, nitrates and borates Fluorspar and limestone are prominent as fluxes in the metallurgical industry and ceramics, and other process industries consume silica sand, feldspars, and kyanite Physical attributes useful in filler and extender applications make talc, limestone and kaolin competitive in paints, paper and plastics Other minerals with useful physical properties include asbestos, barytes, diatomaceous earth, and the lightweight aggregates perlite, pumice and vermiculite Hardness is utilized in abrasives such as corundum, garnet and industrial diamond The extensive list of industrially useful minerals makes it clear that a wide range of geological knowledge finds application in the search for industrial minerals and in ensuring products that conform to specifications set by the industrial user Metallic Mineral Deposits The metallic ore minerals are commonly metal compounds such as sulphides and oxides in which the metal content is high compared with rock-forming minerals Natural concentrations of ore minerals form discrete ore bodies that may typically contain only a few percent of the valuable metal Unlike many industrial minerals that find direct use after mining and limited beneficiation, the ore minerals, in general, must be reduced to metal by complex processing Modern mining and mineral extraction procedures are tending towards greater use of chemical and bacterial leaching methods for suitable ores, such as in-situ extraction of some uranium deposits, and heap leaching of some gold ores The great bulk of metalliferous ore, however, is mined by surface or underground rock-breaking methods Run of mine ore is first crushed and milled to a fine pulp, from which the desired ore minerals are separated from the gangue minerals by various methods to produce a concentrate Metal is then extracted from the mineral concentrate by further treatment, which may include smelting or various chemical methods such as solvent extraction and electrowinning, followed by refining to market standards The expensive multi-stage process of extraction results in complex engineering works at the site of large ore bodies, often in remote locations The commonly used metals are sometimes grouped for convenience by their geochemical or industrial affinities Base metals include Pb, Zn, Sn and Cu Iron and ferroalloy metals include Cr, Co, Ni, Mn and V Light metals include Al, Ti, Mg, Li and Be The precious metals comprise Ag, Au and PGM (platinum group metals) (Table 1, Figure 5) The attached statistical data illustrate some world production rates and the relative importance of the broad mineral groups in the world economy It should be noted that most metal production tonnages are less by one or two orders of magnitude