Vermiculite and Asbestos

Vermiculite is a naturally occurring mineral that may, in certain cases, contain asbestos. Vermiculite has the unusual property of expanding into worm-like accordion shaped pieces when it is heated. The expanded vermiculite is a fire-resistant, absorbent and odorless material; popular properties for manufacturing and companies used vermiculite to make products such as attic insulation, packing material and garden products.

What is vermiculite insulation and where does it come from?

Vermiculite is mined throughout the world. In the U.S., active vermiculite mining operations are in South Carolina and Virginia. When heated, the vermiculite ore expands into a light and fluffy material, which is fire resistant, inert, absorbent, and odorless. The properties of the vermiculite make it useful in lawn and garden, agricultural, and horticultural products. It is commonly used as an ingredient in:

• potting soil,


• thermal and sound insulation,


• construction material,


• insulation material and


• lightweight, absorbent packaging material.

How is W.R. Grace Co. involved in this issue?

the W.R.Grace company owned and operated a vermiculite mine in Libby, Montana for several years. Much of the vermiculite from this mine was used to make Zonolite attic insulation. They sold this product from 1963 to 1984. More than 75 percent of the vermiculite ore mined in the world came from the Libby mine, which has been closed since 1990.

EPA has found it impossible to estimate the number of homes, businesses and schools that may still contain Zonolite attic insulation.