Vermiculite and Its Uses

Vermiculite is the mineralogical name given to hydrated laminar
magnesium-aluminum-iron silicate which resembles mica in appearance. All
vermiculite ores contain a range of other minerals that were formed
along with the vermiculite in the rock. Vermiculite ores from some
sources have been found to contain asbestos minerals but asbestos is not
intrinsic to vermiculite and only a few ore bodies have been found to
contain more than tiny trace amounts.

Vermiculite mines are surface operations where ore is separated from
other minerals, and then screened or classified into several basic
particle sizes. Vermiculite is found in various parts of the world.
Locations of the predominant commercial mines are in Australia, Brazil,
China, Kenya, South Africa, USA and Zimbabwe.

When subjected to heat, vermiculite has the unusual property of
exfoliating or expanding into worm-like pieces (the name vermiculite is
derived from the Latin 'vermiculare' - to breed worms). This
characteristic of exfoliation, the basis for commercial use of the
mineral, is the result of the mechanical separation of the layers by the
rapid conversion of contained water to steam. During this exfoliation
process, asbestos fibers can potentially be released. The increase in
bulk volume of commercial grades is 8 to 12 times, but individual flakes
may exfoliate as many as 30 times. There is a color change during
expansion that is dependent upon the composition of the vermiculite and
furnace temperature.

Vermiculite has been used in various industries for over 80 years. It is
used in the construction, agricultural, horticultural and industrial
markets. Examples of products that contain vermiculite include potting
soil mixes, loose fill insulation, and packing material.