Silicon is the second most common chemical element with a share of 25% in the earth crust after oxygen. It is mostly found as silicates or oxides in different minerals like quartz, feldspar or mica. Elementary silicon is very rare in nature.
The most important raw material for silicon metal production is very pure quartz, either in form of gravel or quartzite. According to his chemical formula pure quartz has about 47% of silicon, of which about 80% can be recovered in an industrial process.