Does vermiculite insulation contain asbestos fibers?

Prior to its close in 1990, much of the world’s supply of vermiculite came from a mine near Libby, Montana.

This mine had a natural deposit of asbestos which resulted in the vermiculite being contaminated with asbestos.

Attic insulation produced using vermiculite ore, particularly ore that originated from the Libby mine, may contain asbestos fibers.

Today, vermiculite is mined at three U.S. facilities and in other countries which have low levels of contamination in the finished material.