Vermiculite is mined in several places in the world, but the EPA estimates that more than 70 percent of the vermiculite ore used in the manufacture of insulation came from one mine – the Libby Mine in Libby, Mont., – which was located in a region that contained deposits of tremolite asbestos, a natural type of asbestos. As a result, much of the vermiculite ore was found to contain tremolite asbestos, which in turn is present in the insulation.
The insulation in question was produced by the W.R. Grace company, which owned and operated the Libby Mine, and was sold under the trade name Zonolite. Grace discontinued production of Zonolite in 1984 and closed the mine in 1990, but it’s unclear as to how much Zonolite stock remained on the market for sale after that period.
How to recognize it:
Zonolite insulation looks like small, slightly puffy nuggets about 1/8 to 1/4 of an inch in length (similar in size to a pencil eraser). They range in color from silvery-gray to gold to brown and typically have a slight glittery appearance when clean. After years in the attic, however, Zonolite typically takes on a darker gray or black appearance.
By comparison, rock wool, which is sometimes mistaken for vermiculite insulation because of its similar light gray to dark gray color, is thick and wool-like in appearance, as opposed to granular. Another gray insulation is cellulose, which is simply finely ground or shredded paper or cellulose fiber and again does not have a granular appearance. The other popular type of attic insulation—blown fiberglass—is pink, yellow or white, and has a very fluffy, slightly fibrous appearance, similar to cotton candy.
What to do with it:
As with most forms of asbestos, Zonolite insulation primarily poses a health risk when it’s disturbed and the asbestos fibers have a chance to become airborne. If you have looked in the attic and suspect that you may have Zonolite insulation, your first step is to have it tested to see if does indeed contain asbestos.
Look in the Yellow Pages under "Asbestos consulting and testing," and contact one of the testing laboratories. They can provide you with instructions for how to safely take and package a sample of the material, which you can then send in for testing. The lab will contact you within a couple of days with the results of the test, and can discuss the amount of asbestos – if any – that’s present in the insulation.
If the insulation is found to contain asbestos, it should be removed to prevent possible future health risks to you and your family. Since the removal process will obviously stir up the fibers in the insulation, the EPA strongly recommends that you not attempt to do the removal yourself. Instead, check the Yellow Pages again under "Asbestos abatement," and contact a properly licensed abatement company to do the removal work.
For more information, including color pictures of what vermiculite looks like, visit the EPA web site at www.epa.gov, or call them at 1-800-424-4372.
