In March 1971, the Arizona Bureau of Mines—predecessor of today’s Arizona Geological Survey—published the first issue of Fieldnotes. For nearly 40 years, Fieldnotes, and its successor, Arizona Geology, showcased all things geologic in Arizona. From the onset, the quarterly magazine printed topical pieces on Arizona’s mineral resources, energy potential, and environmental geology. In Fall 1988, Fieldnotes became Arizona Geology, and the newsletter was retailored to meet the needs of Arizona’s exploding population. There was increased focus on articles describing geologic phenomena—flash floods and regional floods, earthquakes, landslides, volcanism, swelling and shrinking soils, earth fissures, and more—with the most immediate and adverse impact on the lives and properties of our fellow Arizonans. But that was then and this is now! As print publication costs rise through the stratosphere, we simply can no longer afford to print and mail 4100 copies of Arizona Geology quarterly. Arizona Geology is going digital. We are suspending the print publication immediately and we are moving from a quarterly schedule to three times annually.

Pima County is endowed with many mineral resources, not only copper mines, but also the important products such as sand, gravel, and limestone used everyday in supporting the infrastructure of our cities. It is essential that these mineral resources, and the lands where they occur, remain available for exploration and development. This report presents an assessment of the mineral resources of Pima County based on hard data derived from many experienced geologists working in the private sector and from publications of state and federal government agencies.