Vermiculite was a popular insulating material produced by U.S. based W.R. Grace and sold by the tradename ``ZONOLITE``. It was used in thousands of Canadian homes primarily as attic insulation. Vermiculite was called the miracle material, once heated it was used for potting soil, fireproofing and insulation. It was a very popular product from the 1950`s to the late 1i970`s but has not been sold since 1984.
Vermiculite by itself is harmless. Vermiculite is a volcanic material compound that expands when it is heated and has the unusual property of expanding into work- like or accordian- like pieces. They are usually the size of a nickel or dime. Unfortunately, over 70 % of the vermiculite ore mined in the world came from Libby, Montana and that particular mine was naturally contaminated with tremolite an extremely carcinogenic form of asbestos.
If your home in insulated with vermiculate insulation it is advised that you have an asbestos specialist ascertain (through an environmental lab) if asbestos is present. If the asbestos laden vermiculite is exposed to the home environment the best advice would be to have an asbestos removal specialist remove it and replace it with safer insulation.