There are lot of silica mines built in the recent times. The current price of high-quality silica sand ranges from about $50 to more than $100 per ton. The places that contains hundreds of millions of tons, meaning it could turn into a multi-billion dollar industry that employs hundreds during the next few decades. Silica is the more abundant element in the Earth’s crust after oxygen. It does not exist in its pure or original form but rather belongs to silicate class as silicon di oxide. The most common mineral is quartz.
Quartz is usually colourless bit it has the property to imbibe purities which gives different shade. Different colours of pink, purple or green occurs because of the impurities in quartz. The quartz is a metamorphic rock. Volcanic areas are also rich in minerals. Silicification, which is an important indicator of hydrothermal alteration, is not recognizable on TM and hyperspectral images. Quartz has no diagnostic spectral features in the visible and reflected IR wavelengths recorded by these .systems. Variations in silica content are recognizable in multispectral thermal IR images, which is a promising topic for research.
The difference between the two forms of silica is often razor thin. A 2011 report from the Wisconsin Department of Natural Resources says distinguishing between crystalline and amorphous silica is “not always clear cut” and that the forms of silica can change depending on temperature and treatment.
They use the hydraulic fracturing. This extracts oils and natural gas through hydraulic drilling. Water and chemicals are injected into horizontal fissures deep underground. This helps in easier extraction of oil and natural gas. However this leads to a lot of environmental impact. Infact, in South Africa a moratorium is imposed to determine the health hazard posed by these mining procedures. The Toxic research centres have found that there are two varieties of silica- crystalline silica and amorphous silica. Amorphous variety is carcinogenic. Small particles, when inhaled leads to deposits in the lungs. Over a period of times, they eventually build into dangerous levels.