Silica is found in the Earth’s crust, which is its most abundant source. Silica is derived from many different materials including rocks, sand, clay, and some soils. When combined with oxygen and other minerals, it is present in the form of silicon dioxide; meanwhile, it can also be found as silicates in some instances. Silica is used in many different applications and so, silica sand manufacturers mine it from the earth for use as proppants and for other