Pioneer District

Site Name

Primary: Pioneer District
Secondary: Rico District

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Commodity

Primary: Silver
Primary: Zinc
Primary: Lead
Primary: Copper
Secondary: Sulfur-Pyrite
Secondary: Gold
Secondary: Sulfur, Sulfuric Acid
Secondary: Cadmium
Tertiary: Iron
Tertiary: Manganese
Tertiary: Aluminum

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Location

State: Colorado
County: Montezuma
District: Pioneer (Rico) District

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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.
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

Not available

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Production

Not available

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Deposit

Record Type: District
Operation Category: Past Producer
Operation Type: Unknown
Years of Production:
Organization:
Significant: N

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Physiography

General Physiographic Area: Intermontane Plateaus
Physiographic Province: Colorado Plateaus
Physiographic Section: Canyon Lands

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Mineral Deposit Model

Model Name: Polymetallic replacement

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Orebody

Not available

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Structure

Type: L
Description: Rico Dome, Calico Peak Anticline; Principal Named Faults: Alaskite, Blackhawk, Futurity, Hidden, Honduras, Knob Hill, Last Chance, Nellie Bly, Princeton, Sandstone Mountain, Silver Creek, Smelter, South Park, Spruce Gulch, 210 Drift, Yellow Jacket

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Alterations

Alteration Type: L
Alteration Text: Oxidation Of Pyrite Replacement To Au-Ag-Bearing Limonitic Iron Ore; Alteration Of Manganiferous Carbonates To Mn Oxides; Alteration Of Base-Metal Sulfides To Carbonates And Sulfates; Alteration Of Ag Minerals (Argentite) To Native Ag And Embolite (Cerargyrite And Bromyrite); Sericitization Of Feldspar In Porphyry And Arkosic Sandstone; Solfataric Alteration To Alunite At Calico Peak.

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Rocks

Not available

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Analytical Data

Not available

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Materials

Ore: Alunite
Gangue: Epidote
Gangue: Barite
Gangue: Celestite
Gangue: Limonite
Gangue: Rhodochrosite
Gangue: Pyrolusite
Gangue: Alabandite
Gangue: Siderite
Gangue: Garnet
Gangue: Aragonite
Gangue: Magnetite
Gangue: Allanite
Gangue: Rutile
Gangue: Dolomite
Gangue: Allophane
Gangue: Helvite
Gangue: Fluorite
Gangue: Calcite
Gangue: Clinozoisite
Gangue: Chlorite
Gangue: Serpentine
Gangue: Topaz
Gangue: Diaspore
Gangue: Andalusite
Gangue: Cordierite
Gangue: Tourmaline
Gangue: Prehnite
Gangue: Sericite
Gangue: Kaolinite
Gangue: Jarosite
Gangue: Molybdenite
Gangue: Tetradymite
Gangue: Huebnerite
Gangue: Sphene

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Comments

Comment (Deposit): MINES, PIONEER MINING DISTRICT, DOLORES COUNTY, COLORADO: UNPUB. ENG. REPT., 8 P.; (18) MUILENBURG, G.A., 1919, MANGANESE DEPOSITS OF COLORADO: CGS BULL. 15, P. 48-49; (19) NAESER, C.W., AND OTHERS, 1980, PLIOCENE INTRUSIVE ROCKS AND MINERALIZATION NEAR RICO, COLORADO: ECON. GEOLOGY, V. 75, NO. 1, P. 122-127; (20) PARKER, B.H., JR., 1968, PLACER GOLD IN SOUTHWESTERN COLORADO, IN SHOMAKER, JOHN, ED., GUIDEBOOK OF SAN JUAN-SAN MIGUEL-LA PLATA REGION, NEW MEXICO AND COLORADO: NEW MEXICO GEOL. SOC. 19TH FIELD CONF. GUIDEBOOK, P. 178-179; (21) PARKER, B.H. JR., 1974, GOLD PLACERS OF COLORADO: COLORADO SCHOOL MINES QUART., V. 69, NO. 4, P. 190-194; (22) PRATT, W.P., 1968, SUMMARY OF THE GEOLOGY OF THE RICO REGION, COLORADO, IN SHOMAKER, JOHN, ED., GUIDEBOOK OF SAN JUAN-SAN MIGUEL-LA PLATA REGION, NEW MEXICO AND COLORADO: NEW MEXICO GEOL. SOC. 19TH FIELD CONF. GUIDEBOOK, P. 83-87; (23) PRATT, W.P., 1976, PRELIMINARY GEOLOGIC MAP OF THE HERMOSA PEAK QUADRANGLE, DOLORES, SAN JUAN, LA PLATA,

Comment (Deposit): REPLACEMENTS; VEINS TIGHT AND BARREN IN SHALE. LATER, EAST-WEST-TRENDING, GREATER DISPLACEMENT CROSS VEINS DISPLACE VERTICAL VEINS, DRAGGING ORE ALONG CROSS VEINS. VERTICAL MINERALIZED VEINS (AND LESS REGULARLY CROSS VEINS) BRANCH UPWARD INTO IRREGULAR FRACTURES AND STRINGERS AND BECOME IMPOVERISHED WITHIN 5 TO 20 FT OF OVERLYING CRUSHED AND MINERALIZED LIMESTONE, BARREN BLACK SHALE, AND DISTURBED GYPSUM BEDS. FOURTH TYPE IS RICH CONTACT OR BLANKET REPLACEMENT IN CRUSHED OR BRECCIATED (POSSIBLY KARSTIFIED) LOWER HERMOSA LIMESTONE ABOVE VERTICAL AND CROSS VEINS ON NEWMAN HILL. OTHER HYPOGENE REPLACEMENT ORE OCCURS IN POROUS, RESIDUAL, SOLUTION BRECCIA OF GYPSUM BED FILLED BY SLUMPED SHALE FROM OVERHEAD. ALTHOUGH CLASSED AS BLANKET VEINS, MOST OAR LINEAR TO TABULAR IN SHAPE, AND INTERSECTING TRENDS AND STOPES OVER VERTICAL AND CROSS VEINS FORMS RHOMBOID PATTERN. OVERLYING IMPERVIOUS SHALE KEPT WATER OUT OF WORKINGS AND INHIBITED ORE OXIDATION. OTHER (FIFTH) TYPES OF REPLACEMENT INCLUDE

Comment (Location): (LAND STATUS AND ADMINISTRATIVE AREA LOCATIONS CALCULATED USING GIS OVERLAY ANALYSIS FOR SAN JUAN N. F.). ; INFO FROM LAND.ST :1975

Comment (Deposit): (A) MAGNETITE IN LIMESTONE NEAR EXPECTATION MTN, AND (B) ALUNITE REPLACEMENT FORMED BY NEAR-SURFACE SOLFATARIC ALTERATION OF CALICO PEAK PORPHYRY. SEVENTH TYPE IS AU PLACER FORMED IN QUATERNARY ALLUVIUM AND TERRACE GRAVEL ALONG DOLORES RIVER FROM BURNETT CREEK TO TENDERFOOT CREEK. ORES IN DISTRICT CHARACTERIZED BY VERY LIMITED VERTICAL RANGE, CONTROLLED PARTLY BY BOUNDING OF HERMOSA LIMESTONE OVER DOMED AREA; VEINS BECOME BARREN OF SULFIDES AT MAXIMUM OF ABOUT 150 FT BELOW BLANKET ORES. NEAR-SURFACE OXIDATION ON DOLORES MTN EXTENDS 30 TO 40 FT BELOW BLANKET AND POSSIBLY TO 200 FT, NORTH OF SILVER CREEK. ALTERATION FACILITATED BY DECOMPOSITION OF MANGANIFEROUS CARBONATE GANGUE. REPLACEMENT PYRITE OXIDIZED TO AURIFEROUS LIMONITE. SOME DOWNWARD ENRICHMENT OF AG AS ARGENTITE AND PEARCEITE. PARAGENESIS RELATED TO MONZONITE STOCK INDEFINITE, MCKNIGHT (1974) GIVES GENERALIZED SEQUENCE FOR SOME ORE AND GANGUE: (1) QUARTZ, RHODONITE, RHODOCHROSITE; (2) PYRITE; (3) SPHALERITE; (4) GALENA,

Comment (Deposit): DISTRICT KNOWN BY POPULAR NAME OF "RICO" BUT BLM CLAIM RECORDS ASSIGN DISTRICT NAME OF "PIONEER" NAMED AFTER FIRST LOCATED CLAIM. ADDITIONAL REFERENCES: (11) BASTIN, E.S., 1922, SOLVER ENRICHMENT IN THE SAN JUAN MOUNTAINS, COLORADO: USGS BULL. 735-D. P. 110-129; (12) COLLINS, G.E., 19318 LOCALIZATION OF ORE BODIES AT RICO AND RED MOUNTAIN, COLORADO, AS CONDITIONED BY GEOLOGIC STRUCTURE AND HISTORY: COLORADO SCI. SOC. PROC., V. 12, NO. 12, P. 407-424; (13) FARISH, J.B., 1892, ON THE ORE DEPOSITS OF NEWMAN HILL, RICO, COLORADO; COLORADO SCI. SOC. PROC., V. 4, P. 151-164; (14) HARRER, C.M., AND TESCH, W.J., JR., 1959, RECONNAISSANCE OF IRON OCCURRENCES IN COLORADO: USBM IC-7918, P. 27; (15) HENDERSON, C.W., 1926, MINING IN COLORADO, A HISTORY OF DISCOVERY, DEVELOPMENT, AND PRODUCTION: USGS PROF. PAPER 138, P. 114-117; (16) HEYL, A.V., 1964, OXIDIZED ZONC DEPOSITS OF THE UNITED STATES, PART 3--COLORADO: USGS BULL. 1135-C,P. 85-86; (17) MARRS, G.O., 1925, REPORT ON THE GOLD ANCHOR GROUP OF

Comment (Production): VALUES BY USING AVERAGE PRICES OF $20.55/OZ TO $20.66/OZ AU. CUMULATIVE AG FIGURE ESTIMATED DUE TO NECESSARY ROUNDING. CUMULATIVE PB, CU, AND AU FIGURES ESTIMATED DUE TO HENDERSON'S ESTIMATED ANNUAL FIGURES TABULATED FOR EARLY YEARS OF PRODUCTION. NO PRODUCTION REPORTED FROM DISTRICT IN 1958. LAST YEAR OF REPORTED PRODUCTION WAS 1977.

Comment (Production): COMPLETE PRODUCTION RECORD (EXCEPT FOR ORE TONNAGES) FOR 1879-1975. ALL METALS FIGURES FOR 1879-1968 ARE FROM MCKNIGHT, 1974 (AS COMPILED FROM DIRECTOR OF MINT REPORTS (1879-1896), COLORADO BUR. MINES REPORTS (1897-1904), AND USGS MINERAL RESOURCES OF U.S. (1905-1923) AS COMPILED IN HENDERSON, 1926; FROM USGS/USBM MINERAL RESOURCES OF U.S. AND USBM MINERAL YEARBOOKS (1924-1962); AND FROM USBM UNPUBLISHED STATISTICS (1963-1968). 1969 FIGURES ARE FROM USBM MINERAL YEARBOOK. ALL FIGURES FOR 1970-1976 COMPILED FROM COLO. DIV. MINES ANNUAL OPERATOR REPTS. FOR RICO-ARGENTINE AND ST. LOUIS MINES (ONLY OPERATING PROPERTIES IN DISTRICT) AS THOSE FIGURES WERE WITHHELD IN MINERAL YEARBOOKS. PYRITE FIGURES FOR 1943-1945 FROM COLO. DIV. MINES ANNUAL OPERATOR REPTS. FOR RICO-ARGENTINE MINE; OTHER PYRITE WAS PRODUCED INTO EARLY 1960S, BUT FIGURES ARE UNAVAILABLE. SULFURIC ACID WAS MANUFACTURED FROM PYRITE, BUT PRODUCTION AMOUNTS ARE UNAVAILABLE. CD FIGURES FOR 1969-1971 AND 1973 ARE FROM COLO. DIV.

Comment (Production): MINES ANNUAL OPERATOR REPTS. FOR RICO-ARGENTINE AND ST. LOUIS MINES; CD RECOVERY IN OTHER YEARS UNCERTAIN. DISTRICT PRODUCED SMALL AMOUNTS OF FE ORE FOR SMELTER FLUX, BUT FIGURES ARE UNAVAILABLE. ORE TONNAGES NOT REPORTED FOR 1879-1903. ORE TONNAGES REPORTED FOR LATER YEARS (1906, 1917, 1926-1927, 1933-1936, 1938-1976) REFLECT PRODUCTION ONLY FROM PIONEER DISTRICT; ORE FIGURES FOR ALL OTHER INTERVENING YEARS FROM 1904 TO 1937 NOT REPORTED SEPARATELY BUT COMBINED WITH LONE CONE DISTRICT. ORE FIGURES WITHHELD IN USBM MINERAL YEARBOOKS FOR 1963-1968 AND 1970-1977. FIGURES FOR AU AND AG FOR 1879-1880 AND 1885, PB FOR 1879-1885, CU FOR 1879-1883 AND 1893-1894, ZN FOR 1896-1901 WERE ESTIMATED AND/OR INTERPOLATED BY HENDERSON (1926). AU AND AG FOR 1896-1903 DERIVED BY SUBTRACTING ESTIMATED AMOUNTS FOR LONE CONE DISTRICT. AU FIGURES FOR 1879 TO AT LEAST 1937 MOST LIKELY EXCLUDE SMALL AMOUTN OF AU DERIVED FROM PLACERING. AU FIGURES FOR 1879 TO AT LEAST 1903 CALCULATED BY MCKNIGHT FROM REPORTED

Comment (Deposit): GEOLOGIC SETTING CHARACTERIZED BY MAJOR EAST-WEST-TRENDING, BREACHED, ELLIPTICAL DOME (RICO DOME), WHICH HAS UPLIFTED MISSISSIPPIAN TO CRETACEOUS SEDIMENTARY ROCKS AROUND COMPLEXLY FAULTED CORE CONTAINING HORST OF PRECABRIAN QUARTZITE, GREENSTONE, AND METADIORITE. UPLIFT FORMED BY CRETACEOUS TO EARLY TERTIARY HORNBLENDE LATITE PORPHYRY LACCOLITHIC SILLS AND DIKES, LATER CRETACEOUS TO TERTIARY AUGITE MONZONITE STOCK ON DOME AXIS, AND PLIOCENE ALASKITE PORPHYRY AND CALICO PEAK PORPHYRY. MAIN TYPE OF ORE DEPOSIT IS MASSIVE SULFIDE REPLACEMENT IN MIDDLE HERMOSA FM LIMESTONE ALONG PORPHYRY INTRUSIONS AND NEAR INTERSECTIONS WITH FAULTS AND FRACTURES, AND CONTROLLED BY DOMINANT TRUNK CHANNEL ALONG NW-TRENDING BLACKHAWK FAULT. DOMINANT SULFIDES INCLUDE PYRITE, SPHALERITE, ARGENTIFEROUS GALENA, ARGENTIFEROUS CU SULFIDES, IN GANGUE OF QUARTZ, FLUORITE, RHODONITE/RHODOCHROSITE, AND MANGANIFEROUS CARBONATES. SPHALERITE AND GALENA USUALLY MASSED AT OUTER PERIPHERY OF PYRITE MASSES; ALSO MASSED AT

Comment (Deposit): TOP OF PYRITE WHERE COMPLETE THICKNESS OF LIMESTONE NOT REPLACED. CHALCOPYRITE FOUND IN SPHALERITE AND GALENA AND AS SEGREGATIONS IN PYRITE. MINERALIZATION MAY EXTEND IRREGULARLY AS DISSEMINATION (SIXTH MINERALIZATION TYPE) INTO ADJACENT SANDSTONE, SHALE, AND SERICITIZED ARKOSE AND PORPHYRY. SECOND TYPE IS CONTACT-METAMORPHIC MINERALIZATION IN MARBLEIZED OURAY (DEVONIAN) AND LEADVILLE (MISSISSIPPIAN) LIMESTONES, BASAL HERMOSA FM, AND LARSEN (PENNSYLVANIA) QUARTZITE, BASE-METAL SULFIDES OCCUR AS IRREGULAR PODS WITH PYRITE AND QUARTZ SCATTERED THROUGH MASSES OF SPECULARITE, MAGNETITE, AND CHLORITE REPLACING MARBLE AND ASSOCIATED WITH MANGANIFEROUS CALCITE AND SIDERITE GANGUE. THIRD TYPE IS VEINS IN VERTICAL, NE-TRENDING, SMALL-DISPLACEMENT FISSURES IN LOWER HERMOSA FM CONTAINING BASE-METAL AND AG SULFIDES AND PYRITE, WITH SOME FREE AU AND NATIVE AG. VEINS EXPLOITABLE WHERE THEY CROSS SANDSTONE, DISPLACE FOOTWALL SANDSTONE AGAINST HANGING WALL LIMESTONE, OR WIDEN INTO SHALE AND LIMESTONE

Comment (Deposit): AND MONTEZUMA COUNTIES, CPLORADO: USGS OF 76-314; (24) RICKARD, T.A., 1896, THE ENTERPRISE MINE, RICO, COLORADO: AIME TRANS., V. 26, P. 906-980; (25) RICKARD, T.A., 1898, VEIN STRUCTURES IN THE ENTERPRISE MINE, RICO, COLORADO SCI. SOC. PROC., V. 5, P. 123-130; (26) RITTER, E.A., 1913, THE RICO MINING DISTRICT, COLORADO: MINING WORLD, V. 38, P. 895-898; (27) SERNA-ISAZA, M.J., 1971, GEOLOGY AND GEOCHEMISTRY OF CALICO PEAK, DOLORES COUNTY, COLORADO: COLORADO SCHOOL OF MINES THESIS T-1338. INDIVIDUAL RECORDS PREPARED FOR PRINCIPAL MINES AND TYPES OF MINERALIZATION AND UNUSUAL MINERALOGIES: (1) MASSIVE SULFIDE REPLACEMENT (BLANKET VEIN) , FISSURE VEIN, SINGLY OR IN COMBINATION (A. B. G., ARGONAUT, AZTEC, CZLIFORNIA, C. H. C., N.A. COWDREY, ENTERPRISE, EXPECTATION, FALCON, FOREST-PAYROLL, GOLD ANCHOR, IRON CLAD, IRON, JOHNNY BULL, JONES, LEXINGTON, LILLIE D., LOGAN, NEWMAN, PRO PATRIA, PUZZLE, RESOLUTE, RICO-ARGENTINE, RICO-ASPEN, ST. LOUIS, SAMBO, SILVER SWAN, SOUTH PARK, UNCLE REMUS,

Comment (Deposit): UNION-CARBONATE, WELLINGTON, YELLOW JACKET); (2) CONTACT METAMORPHIC (ATLANTIC CABLE, MONTEZUMA, SHAMROCK); (3) OTHER REPLACEMENTS (EAGLE PROSPECT, MAGNET PROSPECT, CALICO PEAK ALUNITE; (4) PLACER (DOLORES RIVER PLACERS). ; INFO.SRC : 1 PUB LIT; 2 UNPUB REPT

Comment (Deposit): TETRAHDERITE-TENNANTITE; (5) CHALCOPYRITE, COSALITE; (6) DOLOMITE, CALCITE; (7) FLUORITE; (8) AG SULFIDES; (10) PYRITE, QUARTZ. NAESER AND OTHERS' (1979) AGE DATES SHOW LATE CRETACEOUS TO EARLY TERTIARY EMPLACEMENT OF HORNBLENDE LATITE PORPHYRY AND MONZONITE, BUT DISCORDANT AGES INDICATE LATE TERTIARY THERMAL RESETTING OF APATITES, POSSIBLY CAUSED BY BURIED INTRUSION ON EAST SIDE OF RICO AND PROBABLY RELATED TO CALICO PEAK STOCK AND ALASKITE PORPHYRY (BOTH DATED AS PLIOCENE). AS ORE VEINS CUT BOTH HORNBLEND LATITE PORPHYRY AND ALASKITE PORPHYRY, AT LEAST SOME MINERALIZATION AND ALTERATION IS LATE TERTIARY (PLIOCENE); GENERAL TERTIARY AGE ASSIGNED TO ALL DEPOSITS EXCEPT LATTER. SUPERPOSITION OF KNOWN AND POSTULATED INTRUSIVE CENTERS SUGGESTS POSSIBLE PORPHYRY-TYPE MINERALIZATION AT DEPTH.

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References

Reference (Production): MCKNIGHT, 1974, P. 6; HENDERSON, 1926, P. 117; USBM MINERAL YEARBOOKS 1969-1981; COLORADO DIVISION OF MINES ANNUAL OPERATOR REPTS.

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