In naturally occurring quartz is the preferred raw material silicon with oxygen to form silicon dioxide SiO2. For the extraction of the pure element therefore requires a chemical reaction in motion, the oxygen separates the connection.
At a temperature of 1460 ° C, slightly above the melting point of quartz (1413 ° C) uses the following response:

SiO2 + 2C -> Si + 2CO

It can therefore be in the presence of the element carbon silicon separated. Its combination with carbon to silicon carbide (SiC), is admitted by the melt iron as a catalyst prevented.
Since the isolated high-density silicon, it sinks to the bottom, where it from the other components can be separated.

The resulting material is called Rohsilizium or technical silicon. It has a concentration of 2 to 4% of foreign atoms, inter alia, carbon, iron, aluminum, boron and phosphorus. For the manufacture of electrical components may therefore not yet recovered, so further steps to increase the purity must be.