The Roscoe Placers is a gold and silver mine located in Clear Creek county, Colorado at an elevation of 6,919 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
Elevation: 6,919 Feet (2,109 Meters)
Commodity: Gold, Silver
Lat, Long: 39.74611, -105.43583
Map: View on Google Maps
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Roscoe Placers MRDS details
Site Name
Primary: Roscoe Placers
Commodity
Primary: Gold
Primary: Silver
Location
State: Colorado
County: Clear Creek
District: Lower Clear Creek 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
Ownership
Owner Name: Humphreys Gold Corp.
Home Office: Denver, Co.
Years: 1937 -
Production
Not available
Deposit
Record Type: Site
Operation Category: Past Producer
Deposit Type: Placer
Operation Type: Unknown
Year First Production: 1932
Year Last Production: 1936
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: LENTICULAR, IRREGULAR
Structure
Type: R
Description: Front Range Uplift, Denver Basin
Type: L
Description: Blackhawk Fault, Floyd Hill Fault Zone
Alterations
Alteration Type: L
Alteration Text: Oxidized Au-Bearing Sulfides From Upstream Lode Mining And Milling Wastes
Rocks
Name: Sand and Gravel
Role: Host
Age Type: Host Rock
Age Young: Holocene
Analytical Data
Analytical Data: 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.
Materials
Ore: Gold
Ore: Silver
Gangue: Pyrite
Gangue: Garnet
Gangue: Magnetite
Comments
Comment (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.
Comment (Workings): DREDGE AND DRAGLINE CUTS ALONG STREAM BED
Comment (Location): 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)
Comment (Production): 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.
Comment (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.
Comment (Deposit): A.B. Wilson decoupled Roscoe Placers from all the other Roscoes.
References
Reference (Deposit): PARKER, B.H., JR., 1974, GOLD PLACERS OF COLORADO: COLORADO SCHOOL OF MINES QUART., V. 69, NO. 3, P. 66, 98, 115-126.
Reference (Deposit): SHERIDAN, D.M., AND OTHERS, 1972, GEOLOGIC MAP OF THE EVERGREEN QUADRANGLE, JEFFERSON COUNTY, COLORADO: USGS MAP I-786-A.
Reference (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.
Reference (Deposit): FORBES, R.H., 1933, THE HUMPHREYS GOLD CORPORATION DREDGING OPERATIONS ON CLEAR CREEK: MINES MAG., V. 23, NO. 5, P. 9-10.
Reference (Deposit): GARDNER, E.D., AND GUITERAS, J.R., 1937, PLACER OPERATIONS OF HUMPHREYS GOLD CORPORATION, CLEAR CREEK, COLORADO; USBM IC-6961, 16 P.
Reference (Production): GARDNER AND GUITERAS (1937)
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