Silica sand natural crystalline

Vitreous silica (silica glass) is essentially a supercooled Hquid formed by fusion and subsequent cooling of crystalline silica. It is found ia nature ia fulgerites, ie, fused bodies resulting from lightning striking quart2 sand. 

A variety of mineral-type materials are inorganic polymers [Ray, 1978]. Silica [(SiCLL] is found in nature in various crystalline forms, including sand, quartz, and agate. The various crystalline forms of silica consist of three-dimensional, highly crosslinked polymer chains composed of Si04 tetrahedra where each oxygen atom is bonded to two silicon atoms and each silicon atoms is bonded to four oxygen atoms. Silicates, found in most clay, rocks, and... 

The common availability of silica is not the sole reason for its extensive use. Probably, it is the chemical inertness and durability of silica which determined its popularity. The fillers discussed here include not only natural minerals but also a variety of synthetic products. Natural products can be divided into crystalline and amorphous. Crystalline silica fillers include sands, ground silica (or silica flour), and a form of quartz - tripoli, whereas the amorphous types include diatomaceous earth. 

Silica, the main component of silicates, is widely used as mentioned earlier. In its crystalline and noncrystalline polymorphs, silica is used industrially as a raw material for glasses, ceramics, foundry molds, in the production of silicon, and more recently in technical applications such as quartz oscillators and optical waveguides for longdistance telecommunications. Of the crystalline forms, only a-quartz is commonly used as sand or as natural and synthetic single crystals. Cristobalite is often utilized as the synthetic phase in glass-ceramics. 

Silica occurs in nature as quartzite rock and ganister, both being composed principally of quartz as sand or sandstone also consisting of quartz as flint pebble which is a crypto-crystalline quartz (i.e. the crystals are too small to be seen under the optical microscope but can be detected in other ways) and as chalcedony, opal and agate, which are also crypto-crystalline quartz. 

Details Crystalline silica, or free silica, occurs in nature. It is white or colourless. Silica is the basic component of quartz, sand, granite, and other mineral rocks. 

Since different phases of silica exhibit different solubility behavior, they are briefly described. By far the commonest crystalline form is quartz, the main constituent of common sand. However, under certain conditions in nature and in the laboratory, other forms arc produced. These forms in turn may be divided into the following classes ... 

Silica and silicates are synthetic and natural. The natural ones (sand, quartz, quartzite, novawite, tripoli, and diatomaceous earth) differ in their particle size, degree of crystallinity, and hardness. 6-Quartz is, moreover, the hardest of the common minerals. Quartz has a density of 2.65 g cm and a Mohs hardness of 7. 

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