The Jamestown District is a fluorine-fluorite and gold mine located in Boulder county, Colorado.
About the MRDS Data:
All mine locations were obtained from the USGS Mineral Resources Data System. The locations and other information in this database have not been verified for accuracy. It should be assumed that all mines are on private property.
Mine Info
Elevation:
Commodity: Fluorine-Fluorite, Gold
Lat, Long: 40.12722, -105.38750
Map: View on Google Maps
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Jamestown District MRDS details
Site Name
Primary: Jamestown District
Secondary: Central
Secondary: Jimtown
Commodity
Primary: Fluorine-Fluorite
Primary: Gold
Secondary: Uranium
Secondary: Copper
Secondary: Lead
Secondary: Silver
Tertiary: Tellurium
Tertiary: Molybdenum
Tertiary: Tungsten
Location
State: Colorado
County: Boulder
District: Jamestown District
Land Status
Not available
Holdings
Not available
Workings
Not available
Ownership
Not available
Production
Year: 1944
Time Period: 1903 through 1944
Mined: 33291.540 mt
Material type: fluorspar (acid spar)
Year: 1944
Time Period: 1903 through 1944
Mined: 64797.750 mt
Material type: fluorspar (metallurgical)
Deposit
Record Type: District
Operation Category: Past Producer
Operation Type: Surface-Underground
Years of Production:
Organization:
Significant: Y
Physiography
Not available
Mineral Deposit Model
Model Name: Alkaline Au-Te (Au-Ag-Te veins)
Orebody
Not available
Structure
Type: L
Description: through-going NW-trending faults
Alterations
Alteration Type: L
Alteration Text: sericitic and silicified wall rocks
Rocks
Name: Alkali-Granite (Alaskite)
Role: Associated
Age Type: Associated Rock
Age Young: Paleogene
Name: Granodiorite
Role: Host
Age Type: Host Rock
Age Young: Paleogene
Name: Granite
Role: Host
Age Type: Host Rock
Age Young: Precambrian
Name: Mafic Gneiss
Role: Host
Age Type: Host Rock
Age Young: Precambrian
Name: Mica Schist
Role: Host
Age Type: Host Rock
Age Young: Precambrian
Analytical Data
Not available
Materials
Ore: Tetrahedrite
Ore: Galena
Ore: Pyrite
Ore: Telluride
Ore: Fluorite
Ore: Gold
Gangue: Quartz
Comments
Comment (Commodity): Gold, and later, fluorspar are the main economic products; silver and lead are of secondary importance. Tellurium might be recovered from the gold-silver telluride ores. Molybdenum has been detected by drilling deep under Porphyry Mountain.
Comment (Location): District is centered on the granite-quartz monzonite porphyry stock of Porphyry Mountain one-half mile north of Jamestown and includes deposits within a radius of about 3 miles. It lies mostly in T 2 N R 71-72 W and occupies about 36 square miles.
Comment (Production): Total value of production since 1865 (to 1943?) estimated at $7,000,000, mostly in gold but including fluorspar valued at about $1,300,000. District output 1901 to 1943, inclusive, totals 57,614.8 oz gold, 200,925 oz silver, 963,951 lb lead, 144,611 lb copper valued at about $1,880,000. Fluorspar production continued until 1973, and its cumulative value now exceeds $25,000,000. Total production of gold estimated slightly over 200,000 oz. and of fluorspar 1 to 1.5 million tons.
Comment (Commodity): Gold-silver telluride minerals present.
Comment (Reserve-Resource): Sunshine Mining Co. evaluated the Jamestown project, including mainly the Bueno mine, in 1992, and concluded that no more work be done. Extensive files include various reports, assays and maps dated from 1930 to 1992 that may have dated or optimistic resource estimates.
Comment (Geology): The Jamestown district is underlain by igneous and metamorphic rocks of Precambrian age and intrusive rocks of Tertiary (Laramide) age. Major northwest-trending faults (breccia reefs) localize ore deposits that are more locally controlled by vein junctions, irregularity of the veins, and physical (chemical) character of wall rocks. Four ore deposit types are lead-silver deposits, fluorspar veins and breccia zones, pyritic gold veins, and gold-silver telluride veins.
References
Reference (Deposit): Vanderwilt, J.W., 1947, Mineral resources of Colorado: State of Colorado Mineral Resources Board, 547 p.
Reference (Deposit): Goddard, E. N., 1946, Fluorspar Deposits of the Jamestown District, Boulder County, Colorado: Colorado Scientific Society Proceedings, v. 15, no.1, 47 p.
Reference (Deposit): LEMMON, D.M. AND TWETO, O.L., 1962, TUNGSTEN IN THE U.S., USGS MAP, MR-25
Reference (Reserve-Resource): Sunshine Mining Co. Colorado exploration files, file ID 14, Boulder County, Jamestown project, unpublished data, available at Colorado Geological Survey.
Reference (Names): Dunn, L.G, 2003, Colorado mining districts: A reference: Golden, Colo., Colorado School of Mines Library, 364 p.
Reference (Production): Koschmann, A. H., and Bergendahl, M. H., 1968, Principal gold-producing districts of the United States: U.S. Geological Survey Professional Paper 610, 283 p.
Reference (Commodity): Nelson-Moore, J.L., Collins, D.B., and Hornbaker, A.L., 1978, Radioactive mineral occurrences of Colorado: Colorado Geological Survey Bulletin 40, 1054 p., 12 pl.
Reference (Production): Brady, B. T., 1975, Map showing fluorspar deposits in Colorado: U.S. Geological Survey Mineral Investigations Resources Map MR-70.
Reference (Geology): Lovering, T. S., and Goddard, E. N., 1950, Geology and Ore Deposits of the Front Range, Colorado: U.S. Geological Survey Professional Paper 223, 319 p.
Colorado Mining Photos
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