Natural Occurrences of Asbestos

Clusters of disease have occurred associated with disturbance of asbestos-containing rocks. The appearance of potentially hazardous minerals often comes as a surprise when construction is not taking place in areas of known asbestos mining. Serpentine is so common in California that it is considered the official State rock, but it typically hosts the asbestos mineral chrysotile, and other minerals may also be encountered. Minerals are defined by chemical composition and crystallography. A suite of amphiboles is regulated because they had been mined for asbestos, but other amphibole compositions exist with different names and these can also be problematic. Unrelated minerals also can exist as fibers in dimensions like asbestos. Chrysotile in homes and farms deposited by floodwaters; dam construction involving fibrous glaucophane; road construction through rocks and soils with fibrous actinolite; and erionite, a fibrous zeolite, are used as examples. Lessons in management can be applied to situations encountered elsewhere.