Vermiculite is a natural mineral, hydrated Aluminium-Magnesium Silicate. It looks like a laminated product dark-greyish coloured, quite soft, of similar aspect to mica, that contain interlaminar water.
It does not contain Asbestos in its composition.
The processed mineral has an aspect of fine and polygonal particles, of variable size, with metallic shining, that may contain small impurities as rest of rocks.
In contact with a flame at high temperature, the interlaminar water evaporates suddenly causing the separation of the laminates and thus its expansion like a bellows or worm, resulting in particles with metal shinning of dark-grey colour, low loose bulk density and a very high porosity.