Quartz flint

Sihca, the other most important class of sihcon compounds, exists as sand, quartz, flint, amethyst, agate, opal, jasper, and rock crystal. It is discussed separately under Sihcon Dioxide. Silicates and silica have many applications... 

By far the most widespread of these oxygen compounds is silicon oxide, or silica (SiOa), which we know in such various forms as sand, sandstone, quartz, flint, agate, and opal. 

Although methods are available for synthesizing silicon dioxide, there is no practical reason for doing so. The abundant quantities of silicon dioxide found in the earth s crust are sufficient to satisfy all industrial needs. Among the minerals and earths that contain silicon dioxide in an uncombined form are quartz, flint, diatomite, stishovite, agate, amethyst, chalcedony, cristobalite, and tridymite. 

Abrasive materials are usually classified into two groups, natural and manufactured ones. The natural abrasives are generally referred to as those that have been produced by the uncontrolled forces of nature and because of that, they can contain many impurities and vary in quality. Emery, corundum, quartz, flint, garnet, diamond, tripoli, diatomaceous earth, sandstone, pumice, and natural sharpening stones are some of them (Krar 1995 Jacobs 1928). On the other hand, artificial abrasives were first developed in the late nineteenth century and overcame the problems of impurities and inconsistencies, since their manufactore could be carefully controlled. Some manufactored abrasives are carbide of silicon, aluminum oxide, glass, and the metallic abrasives such as steel wool and steel shot and grit (Krar 1995 Jacobs 1928) (Table 1). 

Chalcedony. A cryptocrystalline, fibrous form of quartz flint, for example, is chalcedonic. 

The Rosin-Rammler (1933) distribution was first developed for broken coal, but it has since been found to be applicable to many other materials, such as cement, gypsum, magnetite, clay, dyestuffs, quartz, flint, glass, and ores. From probability considerations, the authors obtained... 

Cryptocrystalline flint will show more cristobalite development under heat treatment than will quartz flint. This property has an important bearing on thermal shock resistance of whiteware bodies, allowing more resistant bodies to be made using quartz flint. Impurities in the flint and the fineness to which it is ground have a decided effect on the behavior of the body this effect is probably of more commercial importance than that caused by the type of flint used. The maturing temperature of a body is now lowered materially by the use of cryptocrystalline flint, but overfiring will take place more rapidly than in bodies where quartz flint is used. 

After oxygen, silicon is the most abundant element in the earth s crust, It occurs extensively as the oxide, silica, in various forms, for example, flint, quartz, sand, and as silicates in rocks and clays, but not as the free element, silicon. Silicon is prepared by reduction of silica, Si02- Powdered amorphous silicon can be obtained by heating dry powdered silica with either powdered magnesium or a... 

Silicon makes up 25.7% of the earth s crust, by weight, and is the second most abundant element, being exceeded only by oxygen. Silicon is not found free in nature, but occurs chiefly as the oxide and as silicates. Sand, quartz, rock crystal, amethyst, agate, flint, jasper, and opal are some of the forms in which the oxide appears. Granite, hornblende, asbestos, feldspar, clay, mica, etc. are but a few of the numerous silicate minerals. 

Ground or powdered flint or quartz other than natural sand... 

Flint, quartz, transfers, frits, glazes, dusts... 

Berg-kalk, m. rock time (Geol.) mountain limestone. -kiesel, m. rock flint, chert felsite. -kohle,/. (mineral) coal, -kork, m. mountain cork (a light form of asbestos), -kreide, /. rock lime, -kristall, -krystall, m. rock crystal (transparent quartz), -kupfer, n. native copper, -lasur, /. azurite. -leder, n. mountain leather (a form of asbestos), -maun, m miner. 

Silica, Si02, is a hard, rigid network solid that is insoluble in water. It occurs naturally as quartz and as sand, which consists of small fragments of quartz, usually colored golden brown by iron oxide impurities. Some precious and semiprecious stones are impure silica (Fig. 14.36). Flint is silica colored black by carbon impurities. 

Name from silex (Latin = flint) flint commonly consists of quartz (Si02)... 

Flint is a hard and easily split variety of the mineral quartz (composed of silicon dioxide), which occurs not only as flint but also in a wide range of other varieties. Some of these exhibit different colors and colored patterns and have characteristic crystalline structures, while others are amorphous (see Textbox 21). In all its varieties, nevertheless, the hardness of quartz is very high, being graded as 7 on the Mohs scale (see Textbox 23). Almost all varieties are either transparent or translucent and display a distinctive luster. These properties made quartz an attractive material for making ornamental... 

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