..... Click the link for more information. and larger than those of silt silt, predominantly quartz mineral particles that are between sand size and clay size, i.e., between 1-16 and 1-256 mm ( 1-406 – 1-6502 in.) in diameter. Silt, like clay and sand, is a product of the weathering and decomposition of preexisting rock.
..... Click the link for more information. or clay clay, common name for a number of fine-grained, earthy materials that become plastic when wet. Chemically, clays are hydrous aluminum silicates, ordinarily containing impurities, e.g., potassium, sodium, calcium, magnesium, or iron, in small amounts.
..... Click the link for more information. . Sand is formed as a result of the weathering weathering, collective term for the processes by which rock at or near the earth's surface is disintegrated and decomposed by the action of atmospheric agents, water, and living things. Some of these processes are mechanical, e.g.
..... Click the link for more information. and decomposition of igneous, sedimentary, or metamorphic rocks. Its most abundant mineral constituent is silica, usually in the form of quartz quartz, one of the commonest of all rock-forming minerals and one of the most important constituents of the earth's crust. Chemically, it is silicon dioxide, SiO2.
..... Click the link for more information. , and many deposits are composed almost exclusively of quartz grains. Many other minerals, however, are often present in small quantities, e.g., the amphiboles, the pyroxenes, olivine, glauconite, clay, the feldspars, the micas, iron compounds, zircon, garnet, tourmaline, titanite, corundum, and topaz. Some sands—e.g., coral sands, shell sands, and foraminiferal sands—are organic in origin. Sand grains may be rounded or more or less angular, and differences in shape and size account chiefly for differences in such important properties as porosity (proportion of interstices to the total mass), permeability to gases and liquids, and viscosity, or resistance to flow. Permeability and viscosity are also affected by the proportion of clayey matter present. The chief agents in accumulating sands into deposits are winds, rivers, waves, and glaciers; sand deposits are classified according to origin as fluviatile, lacustrine, glacial, marine, and eolian. The most extensive superficial deposits are seen in the desert desert, arid region, usually partly covered by sand, having scanty vegetation or sometimes almost none, and capable of supporting only a limited and specially adapted animal population.
..... Click the link for more information. and on beaches. The surface of a sand deposit may be level or very gently sloping, or the sand may be gathered by wind action into ridges called dunes. Sandstone sandstone, sedimentary rock formed by the cementing together of grains of sand. The usual cementing material in sandstone is calcium carbonate, iron oxides, or silica, and the hardness of sandstone varies according to the character of the cementing material; quartz
..... Click the link for more information. and quartzite rocks are indurated masses of sand, and sand deposits are sometimes formed by the weathering of sandstone and quartzite formations. Sand is used extensively in the manufacture of bricks, mortar, cement, concrete, plasters, paving materials, and refractory materials. It is also used in the metallurgical industry, in the filtration of water, in pottery making, in glassmaking, in the manufacture of explosives, and as an abrasive. Other industrial uses are numerous. Although soils entirely composed of sand are too dry and too lacking in nourishment for the growth of plants, a soil that is to some extent sandy (a "light" soil) is favorable to certain types of agriculture and horticulture, as it permits the free movement of air in the soil, offers less resistance than a clay soil to growing roots, improves drainage, and increases ease of cultivation. Sand to which nutrient solutions have been added is often used in soilless gardening.
sand
Mineral, rock, or soil particles that are 0.0008–0.08 in. (0.02–2 mm) in diameter. Most rock-forming minerals are found in sand, but quartz is by far the most common. Most sands also contain a small quantity of feldspar, as well as white mica. All sands contain small quantities of heavy rock-forming minerals, including garnet, tourmaline, zircon, rutile, topaz, pyroxenes, and amphiboles. In the pottery and glassmaking industries very pure quartz sands are used as a source of silica. Similar sands are used for lining the hearths of steel furnaces. Molds used in foundries for casting metal are made of sand with a clay binder. Quartz and garnet sands are used extensively as abrasives. Among ordinary sand's many uses, it is a basic ingredient of mortar, cement, and concrete. See also tar sand.
sand
Sand
sand [sand]
Sand
small fragments of loose sedimentary rock or contemporary sediment. Sand consists of round and angular grains of various minerals and rock fragments ranging from 0.1 to 1 mm (from 0.05 to 2 mm or larger, according to other classifications). It also has admixtures of silt (aleurite) and clay particles.
Sand may be designated by its origin as river, lake, sea, fluvioglacial, or eolian sand. In terms of mineralogical composition the most common sands are quartz, glauconite-quartz, feldspar-quartz, and mica sands. Sand may contain valuable minerals— gold, platinum, diamonds, sapphires, rubies, zircon, rutile, sphene, and ilmenite—some of which are extracted. Both natural sand and man-made sand, produced by crushing rock, are used in construction and in the building-materials industry. Quartz sand is used as a raw material in making glass, as a component in manufacturing porcelain, earthenware, and construction ceramics, and as material for making casting molds. The quality of sand is determined by the size of its grains, its mineralogical composition, and the amount of impurities.
Sorted sand must have a strictly regulated grain composition. Natural sand is usually supplied in two grades: large (5–0.63 and 5–1.25 mm) and small (1.25–0.14 and 0.63–0.14 mm). Impurities may not exceed 2 percent. There are two grades of crushed sand, 800 and 400, depending on the strength of the original rock.
REFERENCES
Fadeev, P. I. Peski SSSR, part 1. Moscow, 1951.Trebovaniia promyshlennosti k kachestvu mineral’nogo syr’ia, 2nd ed., issues 2, 29, 74. Moscow, 1959–63.
Grauvakki. Moscow, 1972.
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