Site Background: Asbestos/Vermiculite Exfoliation

Asbestos/Vermiculite exfoliation uses heat to pop or expand the vermiculite ore. Expanded vermiculite is used to manufacture insulation, building products, agricultural products, and fireproofing material.

This exfoliation process released asbestos fibers from the Libby vermiculite ore into the air, where they could be inhaled. It also produced waste material, the unpopped part of the ore, often known as "stoner rock." Before 1991, the Tampa site processed at least 48,991 tons of vermiculite from a mine in Libby.

The Libby mine shut down in 1990. The plant now processes vermiculite from Virginia, South Carolina and South Africa. In contrast, several studies of vermiculite mined elsewhere (South Carolina, Virginia, and South Africa) reported that levels of amphibole asbestos were either not detectable or were present at much lower levels than those found in the Libby vermiculite.