I know it's been around a long time and makes good insulation and is fairly inert but vermiculite has gained a bad rep for asbestos content. A lot of people up here have asbestosis and lung cancer from just living where it is mined.
http://en.wikipedia.org/wiki/Vermiculite
Although not all vermiculite contains asbestos, some products were made with vermiculite that contained
asbestos until the early 1990s. Vermiculite mines throughout the world are now regularly tested for it and are supposed to sell products that contain no asbestos. The former vermiculite mine in
Libby, Montana, did have
tremolite asbestos as well as
winchite and
richterite (both fibrous
amphiboles) in fact, it was formed underground through essentially the same geologic processes as the contaminants. A vermiculite mine in
Virginia has also been found to be contaminated by asbestos.
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Pure vermiculite does not contain asbestos and is non-toxic. Impure vermiculite may contain, apart from asbestos, also minor
diopside or remnants of the precursor minerals
biotite or
phlogopite.
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