mineral, dietary, any of a group of inorganic elements that are essential to humans and animals for normal body function. In nutrition, minerals are those elements for which the body's requirement is at least 100 mg per day, and trace minerals are those elements that are needed in smaller amounts. Dietary minerals are derived from the earth's crust. Plants extract the minerals from the soil, and humans and animals, in their turn, consume the plants. There are seven major minerals. Calcium occurs mainly in the teeth and bones, but a small amount is found in blood plasma and other body fluids, where it influences nerve transmission, blood clotting, and muscle contraction. Dairy products and green leafy vegetables are dietary sources of calcium, and an adequate intake of vitamin D is required for calcium absorption. Phosphorus, also found in dairy products, is closely allied to calcium in bone and tooth formation and its association with vitamin D. It is present in every cell in compounds such as nucleic acids and adenosine triphosphate. Magnesium, also present in every cell, is necessary for carbohydrate and protein metabolism, cell reproduction, and smooth muscle action. Dietary sources include nuts, soy beans, and cocoa. Sodium is in the skeleton and extracellular fluids and is necessary for fluid and acid-base balance, cell permeability, and muscle function. It occurs in table salt (sodium chloride, the main source) and such foods as milk and spinach. Potassium, which is found in intra- and extracellular fluid, plays a major role in fluid and electrolyte balance and in heart muscle activity, and is also required for carbohydrate metabolism and protein synthesis. Its sources include legumes, whole grains, and bananas. Chlorine is found in extracellular fluid, where it helps maintain normal fluid-electrolyte and acid-base balance, and in the stomach, where it helps provide the acidic environment necessary for digestion. Table salt is its main dietary source. Sulfur, which is important to the structure of proteins, is also necessary for energy metabolism, enzyme function, and detoxification. Sulfur is obtained from protein foods, such as meat, eggs, and legumes. Some trace minerals are considered "essential" in human nutrition. The essential trace minerals include iron, which is a constituent of hemoglobin; iodine, which is necessary for thyroxine synthesis; and cobalt, which is a component of vitamin B₁₂. Other essential trace minerals are chromium, copper, fluorine, manganese, molybdenum, selenium, and zinc.

mineral water, spring water containing various mineral salts, especially the carbonates, chlorides, phosphates, silicates, sulfides, and sulfates of calcium, iron, lithium, magnesium, potassium, sodium, and other metals. Various gases may also be present, e.g., carbon dioxide, hydrogen sulfide, nitrogen, and inert gases. Ordinary well or spring water, in contrast, contains far fewer substances, mostly dissolved sulfates and carbonates, and calcium and other alkali and alkaline earth metals. Many mineral waters also contain trace elements that are thought to have therapeutic value. Spa therapy, widely practiced in Europe, advocates bathing in and drinking mineral waters as a cure for a variety of diseases. Many authorities believe that the success of such therapy really results from the beneficial effects of rest and relaxation. Famous European resorts include Bath, Spa, Aix-les-Bains, Aachen, Baden-Baden, and Karlovy Vary (Carlsbad). Prominent among resorts in the United States are Poland, Maine; Saratoga Springs, N.Y.; Berkeley Springs and White Sulphur Springs, W.Va.; Hot Springs, Ark.; French Lick, Ind.; Waukesha, Wis.; and Las Vegas Hot Springs, N.Mex. Many mineral waters are now prepared synthetically, the various mineral ingredients being added to ordinary water in proportions determined by careful chemical analysis of the original ingredients. See spring.

mineral oil: see petrolatum.

mineral, inorganic substance occurring in nature, having a characteristic and homogeneous chemical composition, definite physical properties, and, usually, a definite crystalline form. A few of the minerals (e.g., carbon, arsenic, bismuth, antimony, gold, silver, copper, lead, mercury, platinum, and iron) are elements, but the vast majority are chemical compounds. A generalized formula can usually be assigned to each mineral that is a chemical compound, although sometimes one element in a mineral may be replaced by another without changing the species of the mineral (isomorphism). Minerals combine with each other to make up rocks, which, as distinguished from minerals, are of heterogeneous composition. Minerals may occur in the massive state when conditions for the formation of crystals are unfavorable. Among the important physical properties of minerals are specific gravity, hardness, cleavage, fracture, luster, color, transparency, streak, striations, tenacity, fusibility, heat conductivity, taste, odor, feel, magnetism, and electrical properties. Minerals originate by precipitation from solution, by the cooling and hardening of magmas, by the condensation of gases or gaseous action on country rock, and by metamorphism. Minerals in rocks are frequently replaced by other minerals through the action of water or gases (metasomatism). Minerals, especially the metals, are of great economic importance to a highly industrialized civilization, entering into the composition of many manufactured articles. Many minerals which would otherwise be of no economic significance are highly valued as gems (see gem). Mineralogy, a branch of geology, is the science of minerals.

Mineral Wells, city (1990 pop. 14,870), Palo Pinto and Parker counties, N Tex.; inc. 1882. Aluminum products, bottled mineral water, clothing, and pharmaceuticals are produced, and there is gas processing. The mineral water made this hill city a popular health resort in the late 19th and early 20th cent., and oil activity in the area also spurred the city's growth. To the east is Lake Mineral Wells, a reservoir in the Trinity River system.

or sulphide mineral

Any member of a group of compounds of sulfur with one or more metals. The metals that occur most commonly are iron, copper, nickel, lead, cobalt, silver, and zinc. They are the ore minerals of most metals used by industry (e.g., antimony, bismuth, copper, lead, nickel, and zinc). Other industrially important metals such as cadmium and selenium occur in trace amounts in numerous common sulfides and are recovered in refining processes.

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Any of a large group of silicon-oxygen compounds that are widely distributed throughout much of the solar system. The silicates make up about 95percnt of the Earth's crust and upper mantle, occurring as the major constituents of most igneous rocks and in appreciable quantities in sedimentary and metamorphic rocks. They also are important constituents of lunar samples, meteorites, and most asteroids. In addition, planetary probes have detected them on the surfaces of Mercury, Venus, and Mars. Of the approximately 600 known silicate minerals, only the feldspars, amphiboles, pyroxenes, micas, olivines, feldspathoids, and zeolites are significant in rock formation.

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Any of the forms of silicon dioxide (SiO₂), including quartz, tridymite, cristobalite, coesite, stishovite, melanophlogite, lechatelierite, and chalcedony. Various kinds of silica minerals have been produced synthetically.

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Any naturally occurring inorganic compound with a structure based on close-packed oxygen atoms in which smaller, positively charged metal or other ions occur. Oxide minerals are common in all rock types, whether igneous, sedimentary, or metamorphic.

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or ore dressing

Mechanical treatment of crude ores to separate the valuable minerals. Mineral processing was at first applied only to ores of precious metals but later came to be used to recover other metals and nonmetallic minerals. It is also used during coal preparation to enrich the value of raw coal. The primary operations are comminution and concentration. Comminution is carried out by large jaw crushers and by smaller cylindrical grinding mills. Common methods of concentration are gravity separation and flotation separation. Gravity methods include jigging (ground ore is fed into a pulsating body of water so that the heavier mineral fractions settle out, leaving lighter wastes at the top) or washing the ore down inclined planes, spirals, or shaking tables so that mineral and waste fractions settle in different areas. Seealso beneficiation; mining.

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Any of a class of materials of biologic origin occurring within the Earth's crust that can be used as a source of energy. Fossil fuels include coal, petroleum, and natural gas. They all contain carbon and were formed as a result of geologic processes acting on the remains of (mostly) plants and animals that lived and died hundreds of millions of years ago. All fossil fuels can be burned to provide heat, which may be used directly, as in home heating, or to produce steam to drive a generator for the production of electricity. Fossil fuels supply nearly 90percnt of all the energy used by industrially developed nations.

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Any naturally occurring homogeneous solid that has a definite (but not fixed) chemical composition and a distinctive internal crystal structure. Minerals are usually formed by inorganic processes. Synthetic equivalents of various minerals, such as emeralds and diamonds, are manufactured for commercial purposes. Although most minerals are chemical compounds, a small number (e.g., sulfur, copper, gold) are elements. Minerals combine with each other to form rocks. For example, granite consists of the minerals feldspar, quartz, mica, and amphibole in varying amounts. Rocks are generally, therefore, an intergrowth of various minerals.

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Any of a group of important hydrous aluminum silicates with a layered structure and very small (less than 0.005 mm or microscopic) particle size. They are usually the products of weathering. Clay minerals occur widely in such sedimentary rocks as mudstones and shales, in marine sediments, and in soils. Different geologic environments produce different clay minerals from the same parent rock. They are used in the petroleum industry (as drilling muds and as catalysts in refining) and in the processing of vegetable and mineral oils (as decolorizing agents).

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Any member of a family of minerals that contains the carbonate ion, CO₃²⁻, as the basic structural unit. The carbonates are among the most widely distributed minerals in the earth's crust; the most common are calcite, dolomite, and aragonite. Dolomite replaces calcite in limestones; when this replacement is extensive, the rock is called dolomite. Other relatively common carbonate minerals are siderite, rhodochrosite, strontianite (strontium-rich); smithsonite (zinc-rich); witherite (barium-rich); and cerussite (lead-rich).

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