Commodities
PrimaryGold, Silver
SecondaryCopper, Lead
TertiaryManganese, Molybdenum, Uranium, Antimony, Zinc, Bismuth
Commodity typeM
Deposit
Deposit typeVEIN, DISSEMINATION, REPLACEMENT
Model74: Replacement Mn
Deposit sizeS
Ore controlMETALLIFEROUS VEIN CONTROLLED BY REGIONAL RECTANGULAR FRACTURE SYSTEM IN GRANITES AND BY LOCAL RADIAL FRACTURE SYSTEM ASSOCIATED WITH EMPLACMENT OF CHICAGO BASIN PORPHYRY STOCK; DISSEMINATED MO AND OTHER ANOMALOUS METALS ASSOCIATED WITH HYDROTHERMAL ALTERATION WITHIN AND JUST BEYOND OLDER PHASE OF STOCK, ESPECIALLY IN PRINCIPAL BAND OF MINERALIZED VEINS; REPLACEMENT ORE ASSOCIATED WITH INTERSECTING SHEETED ZONES IN GNEISS AND SCHIST.
Geology
StructureNEEDLE MTNS UPLIFT, CHICAGO BASIN STOCK, EOLUS BATHOLITH, TRIMBLE STOCK, SAN JUAN UPLIFT, SAN JUAN BASIN, SAN JUAN VOLCANIC FIELD
AlterationCHICAGO BASIN STOCK SHOWS ALTERATION RELATED TO THREE SEPARATE PERIODS OF HYDROTHERMAL ACTIVITY. OLDER PART OF PORPHYRY IS FE-STAINED, BLEACHED, SILICIFIED ROCK CHARACTERIZED BY DISSEMINATED PYRITE-MO AND QUARTZ-SERICITE OR QUARTZ-SERICITE-KAOLINITE ASSEMBLAGES IN NETWORKS AND COARSE-GRAINED AGGREGATES. SERICITIZATION MORE INTENSE IN WEST PART OF STOCK. DICKITE-PYROPHYLLITE OF ADVANCED ARGILLIC ASSEMBLAGE IN EASTERN PART SUGGESTS LOCALLY INTENSE HYDROLYTIC ACTIVITY IN WHICHPYROPHYLLITE REPLACED SERICITE. PRIMARY SERICITE HALO IN EOLUS GRANITE AROUND EDGE OF OLDER PART OF STOCK. ALTERATION PHASE LARGELY COMPLETED BEFORE INTRUSION OF INNER YOUNGER PORPHYRY, WHICH CONTAIN INCLUSIONS OF OLDER ALTERED PORPHYRY BUT WHICH ITSELF SHOWS LESS INTENSE ALTERATION--WEAK AND IRREGULAR PLAGIOCLASE REPLACEMENT BY SERICITE, BIOTITE ALTERATION TO CHLORITE, RUTILE, AND SERICITE, LOCALLY INTENSE ARGILLIZATION, MOST COMPLETE AT OUTER MARGINS. LATER MAFIC DIKE CUTTING BOTH PORPHYRIES SHOWS CHOLRITIZED DIOPSIDE AND CLINOPYROXENE. UPPER PARTS OF METALLIFEROUS VEINS SHOW OXIDATION OF RHODOCHROSITE TO MN OXIDES, SUPERGENE ALTERATION OF SULFIDES (CHALCOPYRITE TO AZURITE, MALACHITE, COVELLITE; SPHALERITE TO HYDROZINCITE; GALENA TO ANGLESITE).
Economic & production
Development statusPast Producer
First production1880
Last production1936
Discovery year1880
Identification
Deposit ID60000375
MRDS IDD010711
Alternate namesTacoma District
RegionNA
Data scoreC
Coordinates37.59891, -107.60283
References
CROSS, WHITMAN, AND OTHERS, 1905, DESCRIPTION OF THE NEEDLE MOUNTAINS QUADRANGLE, COLORADO: USGS FOLIO 131.SCHMITT, L.J., AND RAYMOND, W.H., 1977, GEOLOGY AND MINERAL DEPOSITS OF THE NEEDLE MOUNTAIN DISTRICT, SOUTHWESTERN COLORADK: USGS BULL. 1434, 40 P.BARKER, FRED, 1969, PRECAMBRIAN GEOLOGY OF THE NEEDLE MOUNTAINS, SOUTHWESTERN COLORADO: USGS PROF. PAPER 644-A. 35 P.STEVEN, T.A., AND OTHERS, 1969, MINERAL RESOURCES OF THE SAN JUAN PRIMITIVE AREA, COLORADO: USGS BULL. 1261-F.MUILENBURG, G.A., 1919, MANGANESE DEPOSITS OF COLORADO: CGS BULL. 15, P. 49.A WORCESTER, P.G., 1919, MOLYBDENUM DEPOSITS OF COLORADO WITH GENERAL NOTES ON THE MOLYBDENUM INDUSTRY: CGS BULL. 14, P. 68-69.LAKES, ARTHUR, 1897, THE NEEDLES--LA PLATA MOUNTAINS, COLLIERY ENGINEER, V. 18, P. 74-77, 101-103.TRIPPE, T.M., 1905, REPORT ON THE AETNA MINE ACCOMPANIED BY A STATEMENT CONCERNING THE ADJOINING AZTEC AND REPUBLIC CLAIMS, LA PLATA COUNTY: COLO. DIV. MINES FILES, UNPIB. ENG. REPT., 3 P.COLORADO DIV. MINES INF. REPT. (BROOKLYN GROUP).BLM MINERAL SURVEYS