Vermiculite is a natural mineral, a magnesium-iron-aluminium-silicate, which expands approximately 10x in volume when heated between 900 and 1200 degrees. This process of heating in which the grains are ‘inflated’, similar to making popcorn, is called expansion.
The ore is mined in various places in the world in open mines: USA, Australia, China, Russia, Zimbabwe, South Africa, etc.
The special properties of expanded vermiculite are non-combustibility and a high absorption and insulation capacity. It is precisely because of these properties that it is an important additive in the production of insulating mortars. In addition, expanded vermiculite is also used as a soil improver, absorbent, feed additive, etc.
Vermiculite is a natural, non-toxic silicate mineral with the chemical formula (Mg,Fe2+,Fe3+)3[(Al,Si)4O10](OH)2·4H2O. It is generally brown, yellow or dark green, with an oil-like luster, but turns gray when heated.
| Vermiculite |
Physical properties |
| Hardness |
Mohs scale hardness 1.5-2 |
| Density |
50-250 kg/m³ |
| Crystal system |
Monoclinic |
| Luster |
Greasy or vitreous |
| Color |
Colorless, yellow, green, brown, black |
| Diaphaneity |
Translucent |
| Associated mineral |
Asbestos, clay |
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