Asbestos is a term used for several types of naturally occurring fibrous minerals.
The most common and abundant type found in El Dorado County is chrysotile, but tremolite asbestos has also been found. Both types of asbestos occur naturally in serpentine rock, but tremolite may also occur in certain other common rocks, especially near faults. Asbestos is not found in all serpentine rock or fault zones. This variability can occur within the same serpentine rock outcropping. Serpentine rock is abundant in the Sierra foothills, the Klamath Mountains, and the Coast Ranges, where it is commonly exposed near faults.