Section 06 Products of the chemical or allied industries 28 Inorganic chemicals; organic or inorganic compounds of precious metals, of rare-earth metals, of radioactive elements or isotopes 28 04 Hydrogen, rare gases and other non-metals. 28 04 61 Containing by weight not less than 99.99% of silicon Commodity Code Description 28 04 61 00 Containing by weight not less than 99.99% of silicon