Vermiculite are a hydrous silicate mineral which is classified under phyllosilicate.
The expansion of the mineral on heating is termed as exfoliated vermiculite.
It is formed by weathering or hydrothermal alteration of Biotite or phlogopite. 

Colors: Silver & Golden 

Character: Non-toxic, flavorless, lightweight, corrosion resisting, netural PH 6.5-7.5 etc.

Size: 20-40mesh, 40-60mesh, 1-3mm, 2-4mm, 3-6mm, 4-8mm etc.