Jamestown District

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

Name: Jamestown District  

State:  Colorado

County:  Boulder

Elevation:

Commodity: Fluorine-Fluorite, Gold

Lat, Long: 40.12722, -105.38750

Map: View on Google Maps

Satelite View

MRDS mine locations are often very general, and in some cases are incorrect. Some mine remains have been covered or removed by modern industrial activity or by development of things like housing. The satellite view offers a quick glimpse as to whether the MRDS location corresponds to visible mine remains.


Satelite image of the Jamestown District

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

Placer mines at Cripple Creek, Colorado ca. 1892

Check out this collection of Colorado's best historic mining photos: Incredible Photos of Colorado Mining Scenes.