Incas Mine

Site Name

Primary: Incas Mine
Secondary: Van Emmett Property
Secondary: Patented Claims: Incas, MS 17117
Secondary: Unexpected, MS 17118
Secondary: Incas No. 1, MS 18511
Secondary: Oriental, MS 18511
Secondary: Incas No. 2, MS 18513
Secondary: Incas No. 3, MS 18513
Secondary: Northern Slope, MS 18513
Secondary: Unexpected No. 1, MS 18513
Secondary: Unexpected No. 2, MS 18513
Secondary: Unexpected No. 3, MS 18513
Secondary: Great Divide, MS 18513
Secondary: Great Divide No. 2, MS 18513
Secondary: Great Divide No. 3, MS 18513
Secondary: Northern Knight, MS 18513
Secondary: Moonlight, MS 18513
Secondary: Gold Coin, MS 18740

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Commodity

Primary: Silver
Primary: Gold
Secondary: Lead
Secondary: Copper
Tertiary: Zinc
Tertiary: Tellurium

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Location

State: Colorado
County: La Plata
District: California (La Plata) District

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Land Status

Land ownership: National Forest
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.
Administrative Organization: San Juan N. F.

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Holdings

Not available

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Workings

Not available

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Ownership

Owner Name: Incas Mines, Inc.
Home Office: Durango, Co.
Years: 1950 -

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Production

Year: 1917
Material type: AU ACC
Description: Ap_Grade: ^1.46 Oz/Ton Au
Year: 1916
Material type: AG ACC
Description: Ap_Grade: ^1.13 Oz/Ton Au
Year: 1916
Material type: ORE AU AG ACC
Description: Ap_Grade: ^4.8 Oz/Ton Au
Year: 1921
Material type: ORE AU AG ACC
Description: Ap_Grade: ^1.03 Oz/Ton Au

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Deposit

Record Type: Site
Operation Category: Past Producer
Operation Type: Unknown
Year First Production: 1909
Year Last Production: 1922
Discovery Year: 1904
Discovery Method: Ore-Mineral In Place
Years of Production:
Organization:
Significant: N
Deposit Size: S

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Physiography

General Physiographic Area: Intermontane Plateaus
Physiographic Province: Colorado Plateaus
Physiographic Section: Navajo Section

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Mineral Deposit Model

Model Name: Polymetallic veins

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Orebody

Not available

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Structure

Type: R
Description: San Juan Uplift, Four Corners Platform

Type: L
Description: La Plata Dome

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Alterations

Alteration Type: L
Alteration Text: Sericitization, Kaolinitization

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Rocks

Name: Diorite
Role: Associated
Age Type: Associated Rock
Age Young: Paleocene

Name: Diorite
Role: Associated
Age Type: Associated Rock Unit
Age Young: Paleocene

Name: Diorite
Role: Associated
Age Type: Host Rock
Age Young: Late Jurassic

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Analytical Data

Analytical Data: CRUDE ORE MINED IN 1921-1922 CONTAINED 1 TO 1.465 OZ/TON AU AND 0.9TO 1.39 OZ/TON AG

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Materials

Ore: Galena
Ore: Pyrite
Ore: Sphalerite
Ore: Gold
Gangue: Quartz
Gangue: Calcite
Gangue: Ankerite

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Comments

Comment (Location): (LAND STATUS AND ADMINISTRATIVE AREA LOCATIONS CALCULATED USING GIS OVERLAY ANALYSIS FOR SAN JUAN N. F.). CLAIMS LIE NORTH OF LITTLE DEADWOOD GULCH ON TOP AND ON SE SIDE OF OHWILER RIDGE, 2.3 MILES SSE OF LA PLATA TOWNSITE (UNSURVEYED SECTIONS). ; INFO FROM LAND.ST :1974

Comment (Production): COMPLETE PRODUCTION RECORD. NO PRODUCTION REPORTED PRIOR TO 1909 OR FOR 1918-1920. AND AFTER 1922. ORE GRADES CITED ARE AVERAGE TENORS OF ORE REPORTED BY ECKEL AND OTHERS. FIGURES FOR 1911 INCLUDE SMALL AMOUNT OF PRODUCTION FROM GOLD COIN CLAIM.

Comment (Deposit): COUNTRY ROCKS CONSIST OF SW-DIPPING JURASSIC SEDIMENTARY ROCKS INTRUDED BY DIORITE-MONZONITE PORPHYRY SILLS AND DIKES. FOUR MAIN VEINS OR MINERALIZED FAULT ZONES KNOWN AS EAST, BURRIS, BLOUNT, AND NO. 3 AND TREND NW; FIFTH ZONE, NO. 1, TRENDS NNW AND INTERSECTS OTHERS. VEINS CONSIST OF BRECCIATED, SHEETED SANDSTONE UP TO 15 FT WIDE, AVERAGING 3 FT. BRECCIA CONTAINS DISSEMINATED AU LOCALLY ASSOCIATED WITH PYRITE. ALTERED PONY EXPRESS LIMESTONE YIELDED MUCH OF ORE PRODUCED. IN UPPER LEVEL OF MILLER TUNNEL, 3-FT-THICK PONY EXPRESS MEMBER RECRYSTALLIZED TO COARSE-GRAINED MIXED CARBONATE. ORE APPEARS LOCALIZED AS REPLACEMENT IN LIMESTONE NEAR ITS COMMON INTERSECTION WITH VERTICAL VEIN AND EAST-TRENDING PORPHYRY DIKE. CRUSHED, MINERALIZED SANDSTONE (CORRESPONDING TO BILK CREEK MEMBER OF WANAKAH FM) ABOVE LIMESTONE ALSO PRESUMABLY MINED. DEEP NUGGET GOLD MINES TUNNEL DRIVEN TO CUT DOWNWARD EXTENSIONS OF VEINS BELOW WANAKAH AND ENTRADA, BUT APPARENTLY FRACTURES IN DOLORES FM (TRIASSIC) ARE

Comment (Deposit): NARROW AND ONLY SLIGHTY MINERALIZED.

Comment (Workings): MINE DEVELOPED BY NOS. 1 AND 3 TUNNELS, COMBINATION TUNNEL, LOWER PRICE TUNNEL, NEW PRICE TUNNEL, MILLER TUNNEL, SHAFT, AND OPEN CUT. TUNNELS DRIVEN GENERALLY NORTH TO NW INTO EXTENSIVELY MINED AREAS. MILLER TUNNEL DRIVEN GENERALLY N 18 W FOR 660 FT WITH RAISES AT 245 FT, 325 FT, AND 660 FT FROM PORTAL. THIRD RAISE IS 43 FT HIGH, INCLINED AT 80 DEG, EXTENDING TO 190-FT NW-INCLINED UPPER LEVEL.

Comment (Development): INCAS AND UNEXPECTED CLAIMS SURVEYED IN 1904 BY VAN EMMETT GOLD MINING AND MILLING CO., WITH REMAINING CLAIMS SURVEYED IN 1908. FIRST APPARENT PRODUCTION IN 1909, WITH INTERMITTENT PRODUCTION THROUGH 1922. NUGGET GOLD MINES DROVE CROSSCUT IN 1936-1937 TO DEVELOP VEINS AT DEEPER LEVELS.

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References

Reference (Deposit): ECKEL, E.B., AND OTHERS, 1949, GEOLOGY AND ORE DEPOSITS OF THE LA PLATA DISTRICT, COLORADO: USGS PROF. PAPER 219, P. 73-76, 125-129.

Reference (Deposit): COLORADO DIV. MINES INF. REPTS.

Reference (Deposit): BLM MINERAL SURVEYS MS 17117, 17118, 18511, 18513, 18740

Reference (Production): ECKEL AND OTHERS, 1949, P. 126 (AS COMPILED FROM USGS AND USBM RECORDS)

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