- From the 1920s to 1990, a
vermiculite ore produced by the Libby Mine in Montana, USA, may
have contained amphibole asbestos. It was sold in Canada as attic
insulation. This was sold under the brand name of "Zonolite," came
in paper bags & the vast majority of it contained varying
amounts asbestos. As asbestos is naturally occurring in vermeculite
rock, the level of asbestos content from sample to sample can vary.
The type of asbestos found in zonolite is actually a combination of
2 different types of asbestos, & is unique in its mineral
composition by comparison to vermiculite mined in other parts of
the world. For more information see
https://www.asbestos.com/products/construction/zon...
- Not all vermiculite insulation
produced before 1990 contains asbestos fibres.