Are you thinking of purified silicon? Silicon is made starting with quartz, quartzite, or similar minerals rich in silicon dioxide. Crude silicon always requires additional purification for solar uses after it's initially created, so the purity of quartz going into the electric furnace isn't critical.

You can see the process flow from raw materials to completed PV modules here:

http://oasis.mechse.illinois.edu/me432/ME432_L31_Nov4.pdf