Mann Ranch

The Mann Ranch is a uranium mine located in Jefferson county, Colorado at an elevation of 5,801 feet.

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

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.

Site Name

Primary: Mann Ranch
Secondary: Mann Mine
Secondary: Vanadium Queen Mine

Commodity

Primary: Uranium
Tertiary: Molybdenum

Location

State: Colorado
County: Jefferson
District: Foothill District

Land Status

Land ownership: Private
Note: the land ownership field only identifies whether the area the mine is in is generally on public lands like Forest Service or BLM land, or if it is in an area that is generally private property. It does not definitively identify property status, nor does it indicate claim status or whether an area is open to prospecting. Always respect private property.

Holdings

Not available

Workings

Type: Underground

Ownership

Not available

Production

Year: 1958
Material type: 030 U
Description: Ap_Grade: ^0.14% U308
Year: 1956
Material type: U308
Description: Ap_Grade: ^0.36% U308
Year: 1955
Material type: ORE U
Description: Ap_Grade: ^0.21% U308
Year: 1961
Time Period: 1955-1961
Material type: ORE U
Description: Cp_Grade: ^0.27% U308

Deposit

Record Type: Site
Operation Category: Past Producer
Operation Type: Unknown
Year First Production: 1955
Year Last Production: 1961
Discovery Method: Ore-Mineral In Place
Years of Production:
Organization:
Significant: N
Deposit Size: S

Physiography

General Physiographic Area: Rocky Mountain System
Physiographic Province: Southern Rocky Mountains

Mineral Deposit Model

Not available

Orebody

Form: WEDGE

Structure

Type: R
Description: Denver Basin, Front Range Uplift

Type: L
Description: Golden Fault, Damming Fault

Alterations

Not available

Rocks

Name: Sandstone
Role: Host
Age Type: Host Rock Unit
Age Young: Late Cretaceous

Name: Sandstone
Role: Host
Age Type: Host Rock
Age Young: Late Cretaceous

Analytical Data

Analytical Data: ORE GRADES RANGED FROM 0.21 TO 0.27% U308

Materials

Ore: Uraninite
Gangue: Pyrite
Gangue: Ilsemannite

Comments

Comment (Location): ON SOUTH SIDE OF TURKEY CREEK AT BOTTOM OF HOGBACK, JUST ACROSS CREEK FROM FOUR CORNERS MINE ; INFO FROM LAND.ST :(1976)

Comment (Production): ESTIMATED FIGURES FOR 1961 CALCULATED FROM DIFFERENCE BETWEEN RICHTER'S TOTAL FOR 1955-60 AND NELSON-MOORE AND OTHERS' CUMULATIVE TOTAL FOR 1955-61.

Comment (Development): PRODUCTION FROM OLDER ADIT WAS 6 TONS AT 0.21% U308. TOTAL PRODUCTION THRU 1961 WAS 2893 TONS AT 0.27% U308 YIELDING 15579 LB U308

Comment (Deposit): URANIFEROUS ASPHALTIC MATERIAL (PROBABLY RELATED TO OIL SEEPS IN AREA) OCCURS IN ELONGATED WEDGES IN EITHER KASSLER OR UPPER SANDSTONE MEMBERS OF SOUTH PLATTE FM ON FOOTWALL OF DAMMING FAULT. ORE EXTENDS DOWNWARD ALONG BEDDING 10 TO 30 FT FROM FAULT. SIZE AND GRADE OF ORE DECREASE UPWARD ALONG FAULT PLANE. GOLDSTEIN (1957) BELIEVED URANIUM TO BE OF PRIMARY ORIGIN AND WAS PRECIPITATED FROM ASCENDING HYDROTHERMAL SOLUTIONS ALONG DAMMING FAULT AT ZONES OF FAVORABLE SANDSTONE PERMEABILITY.

Comment (Workings): 50-FT TUNNEL DRIVEN SE AND SSE. SECOND TUNNEL DRIVEN N80E FOR 320 FT, THENCE INTO APPROX 300 FT OF DRIFTS TO NW AND SE

References

Reference (Deposit): NELSON-MOORE, J.L., COLLINS, D.B., AND HORNBAKER, A.L., 1978, RADIOACTIVE MINERAL OCCURRENCES OF COLORADO AND BIBLIOGRAPHY: COLORADO GEOLOGICAL SURVEY BULL. 40, P. 193

Reference (Deposit): SCOTT, GLENN R., 1972, GEOLOGIC MAP OF THE MORRISON QUADRANGLE, JEFFERSON COUNTY, COLORADO: USGS MAP I-790-A, 1:24,000.

Reference (Production): RICHTER, 1964, P. 102; NELSON-MOORE AND OTHERS, 1978, P. 193

Reference (Deposit): RICHTER, D.H., 1964, MANN NO. 1 MINE, IN SIMS, P.K., AND SHERIDAN, D.M., GEOLOGY OF URANIUM DEPOSITS IN FRONT RANGE, COLORADO: USGS BULL. 1159, P. 104, PL. 5.

Reference (Deposit): GOLDSTEIN, E.H., 1957, GEOLOGY OF THE DAKOTA FORMATION URANINITE DEPOSIT NEAR MORRISON, COLORADO: ECON, GEOLOGY, V. 52, NO. 7, P. 775-785

Colorado Mining Photos

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