Pinos Altos Mine

The Pinos Altos Mine is a copper, zinc, and silver mine located in Grant county, New Mexico at an elevation of 6,900 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

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Site Name

Primary: Pinos Altos Mine
Secondary: Cyprus Pinos Altos

Commodity

Primary: Copper
Primary: Zinc
Primary: Silver
Secondary: Gold
Secondary: Bismuth
Secondary: Arsenic

Location

State: New Mexico
County: Grant
District: Pinos Altos District

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.

Holdings

Not available

Workings

Not available

Ownership

Owner Name: Exxon Minerals Co.
Home Office: Tucson, Az.
Years: 1972 -

Owner Name: Boliden Minerals Corp., Silver City, N.M. ; Cyprus Minerals/St. Cloud Mining Co. Joint V
Years: 1982 - 1987

Production

Year: 1990
Time Period: 1987-1990
Description: Cp_Grade: ^2.39% Cu, 3.61 Opt Ag, 0.010 Opt Au
Year: 1994
Time Period: 1987-1994
Description: Cp_Grade: ^4.31% Cu, 2.63% Zn, 2.73 Opt Ag, 0.028 Opt Au

Deposit

Record Type: Site
Operation Category: Prospect
Operation Type: Unknown
Discovery Year: 1948
Years of Production:
Organization:
Significant: N
Deposit Size: M

Physiography

General Physiographic Area: Intermontane Plateaus
Physiographic Province: Basin And Range Province
Physiographic Section: Mexican Highland

Mineral Deposit Model

Model Name: Skarn Cu

Orebody

Form: LENSES

Structure

Not available

Alterations

Alteration Type: L
Alteration Text: Outer 10 To 20 Ft Of Quartz Monzonite Pluton Is A Selvage Of Propylitic Or Argillic Alteration. Diorite Stocks On Margin Of Quartz Monzonite Pluton Are Pervasively Potassic-Altered. Lake Valley, Oswaldo And Syrena Limestones Metamorphosed To Marble. Clastics In Syrena Fm Metamorphosed To Wollastonite-Diopside-Tremolite Hornfels. Beartooth Sandstone Annealed To Quartzite.

Rocks

Not available

Analytical Data

Not available

Materials

Ore: Chalcocite
Ore: Copper
Ore: Covellite
Ore: Bismuthinite
Ore: Argentite
Ore: Tetrahedrite
Ore: Bornite
Ore: Chalcopyrite
Ore: Silver
Ore: Sphalerite
Gangue: Marcasite
Gangue: Goethite
Gangue: Sericite
Gangue: Kaolinite
Gangue: Pyrrhotite
Gangue: Garnet
Gangue: Magnetite
Gangue: Pyrite
Gangue: Hematite
Gangue: Quartz
Gangue: Calcite
Gangue: Rhodonite
Gangue: Limonite

Comments

Comment (Deposit): DEPOSIT CONSISTS OF TWO TYPES OF SKARN OCCURRING AS 25,000 TO 500,000 ST OREBODIES. EARLY (STAGE 1) SKARNS CONSIST OF RETROGRADE CALCITE-RHODONITE-PYRITE-SPHALERITE- MAGNETITE-HEMATITE MINERALIZATION OVERPRINTING PROGRADE GARNET SKARNS IN SYRENA FM. LIMESTONE ASSOCIATED WITH POTASSIC-ALTERED DIORITE INTRUSIVES. LATE (STAGE 2) SKARNS CONSIST OF CHLORITE-PYRITE-QUARTZ-CHALCOPYRITE-SPHALERITE-BARITE RETROGRADE MINERALIZATION OVERPRINTING PROGRADE GARNET SKARNS IN OSWALDO AND LAKE VALLEY FMS. LIMESTONE AND AS VEINS IN BEARTOOTH FM QUARTZITE ASSOCIATED WITH PROPYLITIC-ALTERED QUARTZ MONZONITE INTRUSIVES. STAGE 2 SKARN, RICH IN CU, BI, AND AS, OVERPRINTS EARLIER STAGE 1 ZN SKARN MINERALIZATION. WALL ROCK BETWEEN ORBODIES IS BARREN OF MINERALIZATION. EARLY ZN SKARNS ARE LOCATED AT TRANSITION FROM GARNET SKARN TO MARBLE IN THREE FAVORABLE BEDS IN THE SYRENA FM. LATE CU SKARN OVERPRINTS ON EARLY ZN SKARNS OCCUR ALONG NE-SW FRACTURE SETS. CU SKARNS ALSO OCCUR ALONG BASE OF OSWALDO

Comment (Deposit): FM/TOP OF LAKE VALLEY FM. AND ALONG NE-SW/NW-SE TRENDING CONJUGATE FAULT SETS IN BEARTOOTH FM. BEARTOOTH QUARTZITE ORES ARE CU-SILICA FLUX ORES.

Comment (Workings): RANDOM ROOM AND PILLAR MINING AT 450 TPD ORE AND 150 TPD WASTE FROM DEVELOPMENT WORK.

Comment (Development): HOLE DRILLED 1948 BY U.S. SMELTING, REFINING AND MINING CO. CUT A ZN OREBODY. DISCOVERY NOT PURSUED DUE TO HIGH HOLDING COSTS. EARLY 1970'S PROPERTY ACQUIRED BY EXXON MINERALS CO., REDISCOVERED ORE 1973, EXXON DRILLED 213 DIAMOND DRILL HOLES TOTALING 331,375.5 CUMULATIVE FEET DRILLING. SOME 7 MILLION TONS ORE DELINEATED, ALL AS HIGH GRADE OREBODIES SEPARATED BY UNMINERALIZED ROCK. PROJECT SHELVED IN 1978. IN 1982 BOLIDEN MINERALS, INC. LEASED PROPERTY, DID 7,950 FT UNDERGROUND DEVELOPMENT, CONDUCTED PILOT MILL TESTS ON ORE, AND DRILLED 135 DIAMOND DRILL HOLES WITH A CUMULATIVE FOOTAGE OF 77,311 FEET. RESERVES RECALCULATED AS ABOUT 1 MILLION TONS ORE. ABOUT $25 MILLION SPENT BY EXXON AND BOLIDEN. IN 1987 CYPRUS ASSUMED BOLIDEN LEASE IN A JOINT VENTURE AGREEMENT WITH ST. CLOUD MINING, A SUBSIDIARY OF GOLDFIELD. MINING BEGAN OCTOBER, 1987 WITH ST. CLOUD AS OPERATOR. IN LATE 1989 JOINT VENTURE WAS TERMINATED AND CYPURS TOOK OVER. IN 1992 CYPRUS CONVERTED FROM MINING ZN-CU ORE

Comment (Development): TO MINING CU ORES. RESERVES DEPLETED EARLY 1995.

Comment (Reserve-Resource): (1) EXXON ESTIMATE AT A CUT OF GRADE OF 1.23% EQUIVALENT CU. (2) BOLIDEN ESTIMATE AT A 3.4% CUT OFF GRADE.

Comment (Location): LOCATED NORTH AND WEST OF THE NORTHERN END OF THE PINOS ALTOS STOCK ABOUT 1.5 MILES NORTHWEST OF THE TOWN OF PINOS ALTOS.

Comment (Production): (1) TOTAL PRODUCTION 10/1987 TO 6/1994 IN WET ST. MINE HAD ABOUT 5 MONTHS RESERVES IN 10/1994. (2) PRODUCTION OF CU SMELTER FLUX ORE.

References

Reference (Deposit): FINNEL, T. L., 1976 USGS MISC. FIELD STUDIES MAP, MF-779

Reference (Deposit): MCKNIGHT, J. F., AND FELLOWS, M. L., 1978 ARIZONA GEOLOGICAL SOCIETY DIGEST, VOL 11, P. 1-8

Reference (Deposit): ENGINEERING AND MINING JOURNAL, JUNE 1979, VOL 180, NO 6, P. 35, 39

Reference (Deposit): NMBMMR GENERAL FILE DATA

Reference (Deposit): OSTERBERG, M.W., ET. AL., 1992, ORE CONTROLS AT THE CYPRUS PINOS ALTOS CU ZN AG SKARN DEPOSIT, NEW MEXICO: SME/AIME PREPRINT 92-13, 11 P.

Reference (Deposit): OSTERBERG, M. AND MULLER, P., 1994, GEOLOGY OF THE CYPRUS PINOS ALTOS DEPOSIT: CYPRUS-AMAX UNPUBLISHED REPORT, 29 P.

Reference (Production): OSTERBERG AND MULLER (1994), P. 3

Reference (Reserve-Resource): (1,2) OSTERBERG AND MULLER (1994) P. 3-4.

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