Map showing thickness of potash in the Holbrook salt basin, Apache and Navajo Counties, Arizona. Contour interval is 10 ft. Note former helium producing area near northeastern extent of potash deposits and LPG-storage facility near the northwestern extent. Potash (K2CO3) is an essential ingredient of fertilizer, and is used in soap ceramics and glass.
The potash underlies about 600 square miles of the Holbrook Basin and resides in the Permian Supai Formation.
From 'Arizona has Potash' by Steve Rauzi (2008). http://repository.azgs.az.gov/sites/default/files/dlio/files/nid1238/sum...