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The Colvocoresses Collection: Mines & mining in Arizona, Circa 1910-1950

Article Author(s): 

Michael Conway
Casey Brown
Rowena Davis

Figure 1. Distribution of the files, reports and maps comprising the Colvocoresses Collection. (Courtesy of USGS ScienceBase-Catalog. George M. Colvocoresses, Colvo to friends and associates, was a respected and sought after mining engineer and metallurgist during the first half of the 20th century. Mr. Colvocoresses graduated from Yale University in 1900 and was elected to the Mining and Metallurgical Society of America in 1914. At one time in the 1920s, he served as President of the Association of Copper Producers of Arizona. 

Figure 2. Castle Dome Copper Mine, an example of the presentation of documentation of an individual mine file from the Colvocoresses Collection at the Arizona Geological Survey Mining Data website. In spring 2015, the Arizona Geological Survey Mining Data site launched the Colvocoresses collection (Figure 1), comprising reports on field visits or submitted reports from approximately 300 Arizona mine and mining properties by Mr. Colvocoresses or his associates (Figure 2); 100 additional properties from elsewhere in the Southwest are not currently part of the online collection. The materials were originally donated to the Arizona Dept. of Mines and Mineral Resources by the estate of G.M. Colvocoresses; post-1940 additions to the collection came from George’s son, Colonel Alden P. Colvocoresses, or Bill Allison of Allison Steel Company.

Work and Projects

Mr. Colvocoresses spent many years in Humboldt, Arizona, and traveled widely across the American Southwest examining and reporting on 100s of mining prospects, mines and properties. Prior to 1920, Colvocoresses was the general manager of Southwest Metals Company. In late 1921, Southwest Metals acquired Consolidated Arizona Smelting Company and sometime thereafter Mr. Colvocoresses was appointed receiver in the Phoenix office of Consolidated Arizona Smelting Company.

Figure 3. Working map from the Copper Mountain mine file of the Colvocoresses Collection. Copper Mountain is located near Mayer in Yavapai County. In the mid-1920s, Mr. Colvocoresses partnered with Daniel M. Barringer to explore for an iron-nickel meteorite deposit at Meteor Crater, east of Flagstaff, Arizona. In January 1928, and following several frustrating years of dead ends and red tape, the Meteor Crater Exploration and Mining Company, with Barringer as vice president and Colvocoresses as general manager, began operations. A drilling program was designed to drive to 1,400 feet, but ran into substantial problems at about 800 feet attributable to encountering water in the Redwall Limestone. (Arizona Mining News Mining Journal, 8/15/1930)

The Colvocoresses Collection: A partial list

The Colvocoresses Collection at the AZGS Mining Data website includes 329 files (all files are in PDF format) comprising reports, maps (Figure 3), letters, and other documents pertaining to metallic mineral deposits of gold, silver, copper (sulfides and oxides), zinc, lead and other metallic ores. The greatest number of reports stem from, in order of decreasing abundance and with the number of files in parenthesis: Yavapai County (135), Mohave County (34), Maricopa County (31), La Paz County (18), Gila County (12), Pima County (10), Yuma County (7), Cochise and Graham Counties (6), and Coconino County (5).

Table 1. Partial list of Mines included in the Colvocoresses Collection*

Mine Name – Link County Mineral District
Abe Lincoln Yavapai County Black Rock Mineral District
Agua Fria Placer Maricopa County  
American Kirkland Mines Yavapai County Kirkland Mineral District
Artillery Peak Manganese Mohave County  
Big Bug Placers Yavapai County  
Bluebird Cobalt Prospect Graham County  
Cactus Queen Mohave County Cleopatra Mineral District
Castle Dome Copper Mine Gila County  
Christmas Mine Gila County Christmas Mineral District
Globe Arizona Copper Co.  Gila County Pinal Mountains Mineral District
Mineral Hill La Paz County Planet Mineral District
Oatman District Mohave County Oatman Mineral District
Pay Roll Mine Mohave County Wallapai Mineral District
Tiger Gold Yavapai County Tiger Mineral District
Unity Mine Yuma County  
Vulture Mine Maricopa County Vulture Mineral District


*A complete list of mines from the Colvocoresses Collection is located at

File Contents.  File contents may vary greatly from one file to the next; ranging from original, unpublished reports, letters, assays and maps to previously published materials including news and periodical articles.

Figure 4. Mine working of the Magma Mine superposed on a cross section of the geology of the Superior, Arizona, area.By way of example, I’ve detailed below the contents of the 22 page Magma Mine file (Figure 4). In production from 1880 to 1981, Magma Mine was formally an underground mine located near Superior in Pinal County. The mine yielded ore of copper, molybdenum, gold, silver, lead, zinc, manganese, arsenic, bismuth and cadmium hosted in Proterozoic and Paleozoic bedrock (Mindat)

P. 1 – 5    Report of North Magma Copper Company Property: Now Magma Extension Mining Company, Superior, Arizona by Kimball Pomeroy (ca. 1940s)    
P. 6 – 12    Cochran, W.D., 1940, Brief Report on the Magma Extension Mining Company Property, Pioneer Mining District, Pinal County, Arizona.    
P. 13    Letter from H.D. Wollahan to R.M. Auersperg concerning manganese at Magma Mine    
P. 14 – 15     Summary of Engineering and Mining Journal Article of 1 April 1946, Magma Reports Tonnage in New Property.    
P. 16     Letter from G.M. Colvocoresses to W.D. Van Dyke, Jr., Mining in the Superior area (June, 1945)    
P. 17    Letter from G.M. Colvocoresses to W.D. Van Dyke, Jr., Troubling mining reports (May, 1946)    
P. 18 – 20    Letters from W.D. Van Dyke, Jr. to G.M. Colvocoresses, Ongoing correspondence (June, 1946)    
P. 21 – 22    Cross section of Magma Mine showing workings and stratigraphy    



Arizona Mining News Mining Journal, 8/15/1930

Brown, C., Niemuth, N. and Bain, D, 2015, Arizona Geological Survey Mining Data. Arizona Geological Survey Online Mine Data Archive,

Brown, C., 2012, George M. Colvocoresses mining collection inventory. Arizona Geological Survey Open File Report, OFR-12-17, 20 p.

Brown, C. and Allison, M.L., 2012, Arizona Geological Survey Mining Records Digitization Project. Arizona Geological Survey Open-File Report OFR-08-12, 17 p.

Brown, C. 2014, Online mining for riches in historic Arizona mine data: James (Jim) Doyle Sell collection adds new records to AZGS Mine Site. Arizona Geology e-Magazine Summer 2014.  

Hoyt, W. G., 1987, Coon Mountain Controversies: Meteor Crater and the Development of Impact Theory.  University of Arizona Press, Tucson, Arizona, 442 p.

Mindat, 2015, Magma Mine.


Chief, Geologic Extension Service
AZ Geological Survey

Content Manager, Arizona Experience

Digital Librarian
Arizona Geological Survey

AZGS Mining Data Continues to Grow

In 2014, the Arizona Geological Survey launched its mining data website comprising exploration reports and maps for ~ 4,000 mines throughout Arizona. Many of these reports are the unpublished works of geologic consultants that are unavailable elsewhere. Digitized maps span the 20th century and reflect the changing nature of mining and exploration in Arizona.  Maps from the early to mid-century period are generally surface plans or underground sections. Later maps include surface and aerial survey products derived from geophysical exploration methods.

When first launched the site hosted reports, maps and photographs from the former Arizona Department of Mines and Mineral Resources collection. Since February 2014, we have added documents, maps and photographs from 13 private collections, the latest of which is the Colvocoresses Collection. AZGS Mining Data now hosts 7,421 reports (10s of 1000s of pages), 5,466 maps and 5,029 photos, with more to come.

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