What is vermiculite?

Vermiculite is a mineral, similar to mica, that, after being mined, is milled into ore of various sizes and grades. The ore is then expanded by being heated and popped to produce a lightweight product that is used in industries such as construction, agriculture, horticulture, and wherever insulation is needed. The vermiculite, after being expanded, is shaped like small accordion-like pellets, usually gold-brown or metallic in color.




A large part of the vermiculite used in the United States came from a mine in Libby, Montana formerly owned by the Zonolite Company, now known as the W. R. Grace & Co.. This vermiculite mine was contaminated with fibrous amphibole asbestos in varying amounts. Zonolite Attic Insulation (ZAI) was one of the products produced from the Libby, Montana vermiculite. From approximately 1925 to 1984, this Zonolite Attic Insulation was manufactured and sold throughout the United States and Canada. The vermiculite mine in Libby was closed in 1990, and their vermiculite sold today doesn't come from the vermiculite mine in Libby, Montana.


The EPA strongly recommends that vermiculite insulation be left undisturbed because the Zonolite Attic Insulation contains asbestos. There is the potential of asbestos fibers being released into the air where they can be breathed or where they can settle onto building surfaces if there is any disturbance of the vermiculite insulation, and any disturbance afterwards can release this asbestos back into the air, continuing the cycle of exposure.

The following video shows what happens when vermiculite attic insulation is disturbed:


Hatfield's video in the Barbanti case (wmv - 9.37 MB)