Serpentine Subgroup from selected localities.
USA | |
| Van Gosen, Bradley S. (2005) Reported historic asbestos mines, historic asbestos prospects, and natural asbestos occurrences in the eastern United States. USGS Open-File Report 2005-1189. |
| [var: Picrolite] Mineralogy of Pennsylvania - 1922; Samual S. Gordon, pg. 173 |