Vermiculite
Vermiculite is a naturally occurring mineral used in insulation, gardening, and construction products. Vermiculite itself is not asbestos, but the world's largest vermiculite mine — in Libby, Montana, operated by W.R. Grace — was contaminated with tremolite asbestos, resulting in widespread exposure that caused hundreds of asbestos-related deaths.
From the 1920s through 1990, the Libby, Montana vermiculite mine produced approximately 80% of the world's vermiculite supply. The ore deposit was heavily contaminated with tremolite and winchite asbestos fibers. Miners, their families, and Libby residents were exposed to asbestos at catastrophic levels, resulting in an EPA Superfund designation and a public health emergency declaration.
The contaminated vermiculite was sold nationwide under the brand name Zonolite and used primarily as loose-fill attic insulation. An estimated 35 million American homes may contain Zonolite insulation. While undisturbed vermiculite insulation poses limited risk, any disturbance — renovation, insulation removal, or even walking in an attic — can release asbestos fibers.
The Libby disaster is one of the worst cases of industrial asbestos contamination in U.S. history. W.R. Grace established a bankruptcy trust to compensate victims. If you have Zonolite or other vermiculite insulation in your home, do not disturb it — contact a certified asbestos abatement professional for evaluation. Learn about asbestos exposure sources.
- Also known as
- Zonolite, Vermiculite insulation
- Category
- Asbestos
- Related terms
- Chrysotile, Friable Asbestos, Asbestos Abatement, Occupational Exposure, Bankruptcy Trust
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