How-To Make a Hypertufa Planter, Trough and Sculpture ...
Vermiculite resembles mica in appearance. It is crushed and heated aluminium-iron-magnesium silica. The typical vermiculite you acquire from a garden center will have a particle size smaller than perlite and the flake-like nature of vermiculite will make your hypertufa mix, block or scupture shape easier to carve and shape than perlite.