One of the smaller uranium mines in the Monument Valley area of Navajo County, Arizona, the Firelight No.6 Mine has also been referred to as the Naschoy or Noschoy Mine (Young and others, 1964; Chenoweth and Malan, 1973; Scarborough, 1981). Naschoy is a Navajo Indian word meaning "lizard" (Young and Morgan, 1943, p. 51). "Firelight No.6" is the name used in this report, however, because it appears in the official ore-production records of the U.S. Atomic Energy Commission (AEC). I examined the mine in late 1959, while employed by the AEC. Most of the information in this report is from AEC documents. The mapping and geological interpretation of the drill-hole data were done by Rudolph W. Kopf and other AEC geologists who worked in Monument Valley. A map of the underground workings (Figure 1) and other data pertaining to the Firelight No.6 Mine were recently located in the files of the U.S. Geological Survey (USGS) at the Denver Federal Center'! Warren I. Finch of the USGS permitted me to copy the map for the Arizona Geological Survey.