Darby Extension

The Darby Extension is a thorium and ree mine located in Custer county, Colorado at an elevation of 7,799 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: Darby Extension
Secondary: Derby Extension

Commodity

Primary: Thorium
Primary: REE
Tertiary: Barium-Barite
Tertiary: Copper
Tertiary: Lead

Location

State: Colorado
County: Custer
District: Wet Mountains Area; Mckinley Mountain Area

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: Surface/Underground

Ownership

Owner Name: C. L. Briggs, (Patented Mineral Rights)
Home Office: 1808 Juneway Terrace, Chicago 26, Il.
Years: 1953 -

Production

Not available

Deposit

Record Type: Site
Operation Category: Past Producer
Operation Type: Unknown
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

Model Name: Thorium-rare-earth veins

Orebody

Not available

Structure

Type: R
Description: Wet Mountains

Type: L
Description: Large, Northwest-Trending Dead Mule Gulch Fault; Smaller, Northeast-Trending Fault

Alterations

Not available

Rocks

Name: Gneiss
Role: Host
Age Type: Host Rock
Age Young: Paleoproterozoic

Name: Gneiss
Role: Host
Age Type: Host Rock Unit
Age Young: Paleoproterozoic

Analytical Data

Analytical Data: MINOR AMOUNTS OF CE, LA, ND, SM, TH AND Y DETECTED BY SEMI-QUANTITATIVE SPECTOGRAPHIC ANAYSIS
Analytical Data: CHANNEL AND GRAB SAMPLES: 0.19 TO 0.25% EQUIVALENT U, .001 TO .003% U, .12 TO 1.65% EQUIVALENT TH02, 1.39% TH02, 0.18% RARE EARTH OXIDES

Materials

Ore: Barite
Ore: Thorite
Ore: Chalcopyrite
Ore: Galena
Gangue: Calcite
Gangue: Siderite
Gangue: Limonite
Gangue: Quartz
Gangue: Pyrite

Comments

Comment (Location): NEAR DEAD MULE GULCH, ALONG NORTHEASTERN TRIBUTARY; ON A. GRIFFEN RANCH 8 MILES NORTH OF QUERIDA ; INFO FROM LAND.ST :(1976)

Comment (Development): THIS PROPERTY AND THESE MINERAL RIGHTS ARE SEPARATE FROM "GRIFFEN PROPERTY" ALSO ON THE SAME RANCH (1953)

Comment (Workings): TWO SHAFTS, TWO ADITS, NUMEROUS PROSPECT PITS; PROBABLY MOST EXTENSIVE WORKINGS WERE DEVELOPED FOR OTHER COMMODITIES

References

Reference (Deposit): CHRISTMAN, R.A., BROCK, M.R., PEARSON, R.C., AND SINGEWALD, Q.D., 1959, GEOLOGY AND THORIUM DEPOSITS OF THE WET MOUNTAINS, COLORADO, A PROGRESS REPORT: USGS BULLETIN 1072-H, P.522-524.

Reference (Deposit): NELSON-MOORE, J.L., COLLINS, D.B., AND HORNBAKER, A.L., 1978, RADIOACTIVE MINERAL OCCURRENCES OF COLORADO AND BIBLIOGRAPHY: COLORADO GEOLOGICAL SURVEY BULLETIN 40, P.120

Reference (Deposit): BROCK, M.R. AND SINGEWALD, Q.D., 1968, GEOLOGIC MAP OF THE MOUNT TYNDALL QUADRANGE, CUSTER COUNTY, COLORADO: USGS MAP GQ-596.

Reference (Deposit): CHRISTMAN, R.A., HEYMAN, A.M., DELLWIG, L.F., AND GOTT, G.B., 1953, THORIUM INVESTIGATIONS 1950-52, WET MOUNTAINS, COLORADO: USGS CIRCULAR 290, P. 24-25.

Colorado Mining Photos

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