Appearance: White powder ; Hygroscopic fine white powder ; Finely divided white particulate dispersed in air. [Note: Exposure may occur when magnesium is burned, thermally cut, or welded upon.]
Si
Names: Silicon, Si, Element 14Elemental silicon, [Note: Does not occur freely in nature, but is found in silicon dioxide (silica) and in various silicates.]
Appearance: Steel-grey crystals or black-to-brown amorphous powder ; Black to gray, lustrous, needle-like crystals. [Note: The amorphous form is a dark-brown powder.]