The 'Fort Apache Limestone Member' defines a Permian limestone facies within the Fort Apache Indian Reservation. This paper establishes a widespread dolomite facies to the northwest in the Mogollon Rim region and an evaporite-dolomite facies to the north in the Holbrook basin, and suggests that 'Fort Apache Member' would be more appropriate. The member is thickest (about 140 feet) some 40 miles ENE of Fort Apache. Petrographic and textural studies indicate that these rocks were originally aragonitic or calcitic muds that accumulated in a shallow marine environment free of persistant currents or wave motions but periodically subjected to vigorous agitation of the sea bottom. Probably the dolomite is of early diagenetic (syngenetic) origin.