Vermiculite - Definition and Overview

Diamond
Vermiculite
General
Category	Mineral
Chemical formula	(MgFe,Al)3(Al,Si)4O10(OH)2.4H2O
Identification
Colour	Honey
Crystal habit	Clay, scaly, aggregate
Crystal system	Monoclinic
Cleavage	Perfect
Fracture	Uneven
Mohs Scale hardness	2-3
Luster	Vitreous
Refractive index	Translucent
Pleochroism	None
Streak	Pale yellow
Specific gravity	2.4-2.7
Fusibility	?
Solubility	?
Major varieties
None

Vermiculite is a natural mineral which expands with the application of heat. It is formed by hydration of certain basaltic minerals, and is often found in association with asbestos. Mining operations in Libby, Montana were closed in 1990 in response to asbestos contamination. Expanded Vermiculite is used as a soil conditioner, as loose-fill insulating and packing material, as an insulating filler for plaster and concrete compounds, and as a carrier for dry handling and slow release of agricultural chemicals.

World production of Vermiculite in the year 2000 exceeded 500 kilotons (Metric). Major producers of Vermiculite include China, South Africa, Australia, Zimbabwe, and the United States of America.

Vermiculite is often used together with Perlite as a growing medium for hydroponics.

See also

• Perlite
• List of minerals