Commonly found in ultramafic rock, including serpentine rock, and near fault zones. The amount of asbestos typically present in these rocks ranges from less than 1 percent up to more than 25 percent.
Can be released if the rock that contains it is broken or crushed.
In rock formations across the country, including in areas of Washington. It has been documented in some areas of Skagit and Whatcom counties. The most well-known location is the Sumas Mountain slide zone in Whatcom County. Evidence of naturally occurring asbestos has also been found in rocks from the north side of Burlington Hill and to the south of Beaver Lake in Skagit County.