| Singewald, J. T. (1928) Notes on feldspar, quartz, chrome and manganese in Maryland: Maryland Geological Survey vol. 12 part 2: 106-107. Pearre, N. & A. V. Heyl (1960) Mineral deposits in serpentine rocks of the Piedmont Upland, Maryland, Pennsylvania and Delaware: U. S. Geological Survey: Bulletin 1082K: 799. |
Pilot, Cecil County, Maryland, USA