Occurrences of Silica

High class silica sand or clear quartz crystals are combined in order to manufacture ophthalmic glasses and lenses. A great amount of the supply of radio grade quartz comes from Brazil and it can be found in the states of Minas, Bahia, Gerais, and Goiaz in great amounts. The deposits of quartz can be found in the form of veins, pipes, pockets, stock works and rock cavities, however not all the crystals are of radio grade and it is not common to find clear crystals. Only clear pyramid crystals can be chosen for tests, the ones that have a milky or grey color quartz cannot be used.  

The most common uses of silica
The most typical uses of silica sand or quartz and glass sand are for the manufacturing of glass. There has been a great amount of improvement and advancement in the manufacturing of the transparent, translucent colored or clear glass in the form of glassware as well as in sheets. The size of the grains of sand is very vital in the glass industry and it needs to be anywhere between forty to eighty mesh. It also has to have a high purity that has at least ninety eight percent of SiO2. In the case of the manufacturing of colorless glass, the content of iron cannot be above that of 0.04 percent. In the case of when it is utilized for optical purposes, iron oxide over that of 0.008 percent cannot be utilized. In the case of sand glass, iron and chromium are both intolerable impurity in it. Even the most diminutive presence of these impurities will cause color and the glass to melt. Glass is made by melting a mixture of the right amount of feldspar, limestone, dolomite, and ash soda along with glass sand anywhere from 1400 degrees C. to 1500 degrees C. in the furnace and this is then how the molten glass becomes shaped. 

Abrasives
Glass-sand that is free from organic impurities is utilized in the making of sand paper, abrasive cloth and so forth. In most cases the sands that are crushed from sandstone and quartzite are utilized. Sands from rivers cannot be utilized because they do not have the angular faces required.