Vermiculite is a hydrated magnesium aluminium silicate. 

Vermiculite, in its exfoliated (expanded) form, is lightweight, noncombustible, compressible, highly absorbent, nonreactive and may have high cation exchange capacity.

Vermiculite is one of the safesty, most unique minerals in the world.
 
Vermiculite is readily available around the world and is used in numerous applications.