1. Mineral Resources
  2. Online Spatial Data
  3. Mineral Resource Data System (MRDS)

Roscoe Placers

Past Producer in Jefferson county in Colorado, United States with commodities Gold, Silver
Map
XML
JSON
KML
B
Sections on this page
  1. Identification information
  2. Geographic coordinates
  3. Site location context
  4. Geographic areas
  5. Public Land Survey System information
  6. Commodities
  7. Materials information
  8. Alteration
  9. Host and associated rocks
  10. Nearby scientific data
  11. Geologic structures
  12. Ore body information
  13. Controls for ore emplacement
  14. Economic information about the deposit and operations
  15. Mining district
  16. Land status
  17. Ownership information
  18. Workings at the site
  19. Links to other databases
  20. Bibliographic references
  21. General comments
  22. Reporter information

Geologic information

Identification information

Deposit ID 10013746
MRDS ID D010205
Record type Site
Current site name Roscoe Placers

Geographic coordinates

Geographic coordinates: -105.43642, 39.7461 (WGS84)
Elevation 2109
Relative position 6.7 MILES S 75 W FROM GOLDEN

Site location context

Political divisions (FIPS codes)

Clear Creek(county)

Colorado(state)

United States(country)

North America(continent)

Land(continent)

USGS map quadrangles

Saddleback Mountain(quadrangle 1:24,000 scale)

Denver West(quadrangle 1:100,000 scale)

Denver(quadrangle 1:250,000 scale)

Hydrologic units (watersheds)

Clear(hydrologic unit)

South Platte(hydrologic accounting unit)

South Platte(hydrologic subregion)

Missouri(hydrologic region)

Geographic areas

Country State County
United States Colorado Jefferson
United States Colorado Clear Creek

Public Land Survey System information

Meridian Township Range Section Fraction State
6th Principal 004S;004S;003S 071W;072W;072W 05,06;01;36 Colorado

Comments on the location information

  • DISCONTINUOUS WORKINGS OVER ABOUT 4 MILES OF CREEK BED BELOW JUNCTION OF CLEAR CREEK AND NORTH CLEAR CREEK AND ON NORTH CLEAR CREEK, PROBABLY EXTENDING ONTO BLACKHAWK QUAD. ELEV AND LAT-LONG GIVEN ARE FOR JUNCTION OF CLEAR CREEK AND NORTH CLEAR CREEK (SQUAW PASS QUAD). ; INFO FROM LAND.ST :(1975)

Commodities

Commodity Importance
Gold Primary
Silver Primary

Materials information

Materials Type of material
Gold Ore
Silver Ore
Garnet Gangue
Magnetite Gangue
Pyrite Gangue

Alteration

  • (Local) Oxidized Au-Bearing Sulfides From Upstream Lode Mining And Milling Wastes

Analytical data

Result FIRST TESTS SHOWED 30 CENT/YD AT SURFACE AND 80 CENT/YD AT 18-FT DEPTH. DRILLING ESTIMATE IN 1935 INDICATED 43.88 CENT/YD BUT ACTUAL MINING YIELDED 60.95 CENT/YD. AMALGAMATED BULLION YIELDED 850 TO 860 FINE AU AND APPROX 140 FINE AG.

Host and associated rocks

  • Host or associated Host
    Rock type Unconsolidated Deposit > Sand and Gravel
    Rock unit name Post-Piney Creek Alluvium;Piney Creek Alluvium
    Rock description Post-Piney Creek Alluvium;Piney Creek Alluvium
    Stratigraphic age (youngest) Holocene

Nearby scientific data

(1) -105.43642, 39.7461
ListMap

Economic information

Geologic structures

Type of structure Regional
Structure description Front Range Uplift, Denver Basin
Type of structure Local
Structure description Blackhawk Fault, Floyd Hill Fault Zone

Ore body information

  • General form LENTICULAR, IRREGULAR
    Width 73.15M
    Depth to bottom 9.14M

Controls for ore emplacement

  • Coarse Gravel In Meanders At Fault-Weakened Widenings In Stream Valley

Economic information about the deposit and operations

Development status Past Producer
Commodity type Metallic
Deposit size Small
Significant No
Discoverer I. B. Humphrey
Year of first production 1932
Year of last production 1936

Mining district

District name Lower Clear Creek Area

Land status

Ownership category Private

Ownership information

  • Type Owner-Operator
    Owner Humphreys Gold Corp.
    Home office Denver, Co.
    First year 1937

Comments on the production information

  • PARTIAL PRODUCTION RECORD. FIGURES ARE CU YDS GRAVEL PROCESSED; FIGURES FOR OZ AU RECOVERED NOT AVAILABLE. 1934 AND 1935 PRODUCTION FROM CLEAR CREEK BELOW FORKS; 1936 YARDAGE FROM NORTH CLEAR CREEK.

Workings at the site

  • Type of workings Surface
    Length 6437.2M

Comments on the workings information

  • DREDGE AND DRAGLINE CUTS ALONG STREAM BED

Comments on development

  • ATTEMPTS TO WORK GRAVEL BY HYDRAULIC ELEVATING METHODS IN EARLY 1890S FAILED DUE TO INSUFFICIENT WATER PRESSURE. HUMPHREY'S CONSOLIDATION AND OPERATION OF PROPERTIES BY EARLY 1930S FOLLOWED SURFACE AND DRILL-HOLE TESTS OF PAYING GROUND. I.B. HUMPHREY DESIGNED SPECIAL SUCTION DREDGE WITH DIGGING LADDER BUT WAS NOT USED LONG DUE TO BOULDERS ENCOUNTERED AT DEPTH;ALSO BUILT HUMPHREY CONCENTRATOR TO SEGREGATE AU AND BLACK (HEAVY) SAND CONCENTRATES, WHICH WERE STOCKPILED FOR POSSIBLE USE. DRAGLINES, POWER SHOVEL, AMALGAMATION PLANT, AND SLUICES ALSO USED. PYRITE, OXIDIZED AU-BEARING SULFIDES, AND AMALGAM RECOVERED ORIGINATED AT LODE MINING AND MILLING SITES UPSTREAM AT IDAHO SPRINGS AND CENTRAL CITY. PLANT WAS DISMANTLED AT END OF 1936.

Reference information

Bibliographic references

  • Deposit

    PARKER, B.H., JR., 1974, GOLD PLACERS OF COLORADO: COLORADO SCHOOL OF MINES QUART., V. 69, NO. 3, P. 66, 98, 115-126.

  • Deposit

    SHERIDAN, D.M., AND OTHERS, 1972, GEOLOGIC MAP OF THE EVERGREEN QUADRANGLE, JEFFERSON COUNTY, COLORADO: USGS MAP I-786-A.

  • Deposit

    SHERIDAN, D.M., AND MARSH, S.P., 1976, GEOLOGIC MAP OF THE SQUAW PASS QUADRANGLE, CLEAR CREEK, JEFFERSON, AND GILPIN COUNTIES, COLORADO: USGS MAP GQ-1337.

  • Deposit

    FORBES, R.H., 1933, THE HUMPHREYS GOLD CORPORATION DREDGING OPERATIONS ON CLEAR CREEK: MINES MAG., V. 23, NO. 5, P. 9-10.

  • Deposit

    GARDNER, E.D., AND GUITERAS, J.R., 1937, PLACER OPERATIONS OF HUMPHREYS GOLD CORPORATION, CLEAR CREEK, COLORADO; USBM IC-6961, 16 P.

  • Production

    GARDNER AND GUITERAS (1937)

General comments

Subject category Comment text
Deposit HIGHER-GRADE DEPOSITS APPARENTLY DEVELOPED IN MEANDERS AND OTHER WIDE PLACES IN VALLEY WHERE STREAM WAS ABLE TO MOVE LATERALLY AND BUILD VALLEY FILL AT EXPENSE OF BEDROCK WEAKENED BY NW-TRENDING FAULTS DIAGONALLY CUTTING VALLEY. DISCONTINUITY OF PAYING GROUND AND, THEREFORE, PLACER WORKINGS COULD BE DUE TO VALLEY'S PHYSIOGRAPHIC CONSTRICTIONS AND POSSIBLE SLIGHT GRADE CHANGES THROUGH MEANDERS AND WIDE STRETCHES, BOTH OF WHICH WOULD AFFECT STREAM COMPETENCE.
Deposit A.B. Wilson decoupled Roscoe Placers from all the other Roscoes.

Reporter information

Type Date Name Affiliation Comment
Reporter 01-FEB-1983 Schwochow, Stephen D. Colorado Geological Survey
Editor 15-JUL-2008 Wilson, Anna B. U.S. Geological Survey

Beyond USGS

Supplemental information added by qvyshift.com. Not part of the original USGS MRDS record.

Maps centered on this site

Authoritative Colorado resources

These are landing pages for further research — the state agencies don't currently expose per-mine deep links.