How can I tell if my vermiculite insulation contains asbestos?

The majority of all vermiculite insulation produced before 1990 used contaminated vermiculite from Libby.

Asbestos fibers in vermiculite are too small to be seen by the naked eye. Only a trained technician using a microscope can see asbestos fibers.

However, due to limitations in the methods even trained technicians cannot always determine if all vermiculite contains asbestos. Therefore, to be safe, you should assume that vermiculite insulation may be contaminated with asbestos.