Grade names listed: 553, 441, 411, 421, 3303, 3305, 2202, 2502, 1501, 1101.
Industrial route: SiO2 + 2C → Si + 2CO in an electric furnace; source states purity of this product is 97–98%.
After remelt, recrystallization, and acid purification the source states 99.7–99.8% silicon.
Crystalline silicon: diamond structure, melting point 1410 °C, boiling point 2355 °C, Mohs hardness 7, brittle.
Amorphous silicon is described as a grayish-black microcrystalline powder, more chemically active.