El Arco

Past Producer in Baja California, Mexico with commodities Copper, Gold, Molybdenum
Sections on this page
  1. Identification information
  2. Geographic coordinates
  3. Site location context
  4. Geographic areas
  5. Commodities
  6. Materials information
  7. Alteration
  8. Mineral occurrence model information
  9. Host and associated rocks
  10. Nearby scientific data
  11. Economic information about the deposit and operations
  12. Mining district
  13. Ownership information
  14. Reserves and resources
  15. Links to other databases
  16. Bibliographic references
  17. General comments
  18. Reporter information

Geologic information

Identification information

Deposit ID 10098728
MRDS ID MX00099
Record type Site
Current site name El Arco
Alternate or previous names Calmalli, Don Carlos

Geographic coordinates

Geographic coordinates: -113.38544, 28.05579 (WGS84)

Site location context

Political divisions (FIPS codes)

Pima(county)

Arizona(state)

United States(country)

North America(continent)

Land(continent)

Geographic areas

Country State
Mexico Baja California

Comments on the location information

  • ESTIMATED TO NEAREST 5 SECONDS.

Commodities

Commodity Importance
Copper Primary
Gold Secondary
Molybdenum Tertiary

Materials information

Materials Type of material
Bornite Ore
Chalcocite Ore
Chalcopyrite Ore
Covellite Ore
Cuprite Ore
Digenite Ore
Gold Ore
Molybdenite Ore
Pyrite Ore
Albite Gangue
Calcite Gangue
Chlorite Gangue
Epidote Gangue
Feldspar Gangue
Quartz Gangue
Sericite Gangue

Alteration

  • (Local) Zoned Outwardly: Silicic Core Ringed By Potassic And Propylitic Alteration Zones And Pyrite Halo. No Sericitic (Phyllic) Alteration Present.

Analytical data

Result 0.6% CU

Mineral occurrence model information

Model code 53
USGS model code 17
Deposit model name Porphyry Cu
Mark3 model number 4

Host and associated rocks

  • Host or associated Associated
    Rock type Plutonic Rock > Mafic Intrusive Rock > Diorite
    Stratigraphic age (youngest) Early Cretaceous
    Stratigraphic age (youngest) Early Cretaceous
  • Host or associated Associated
    Rock type Plutonic Rock > Mafic Intrusive Rock > Diorite > Diabase
  • Host or associated Host
    Rock type Volcanic Rock (Aphanitic) > Intermediate Volcanic Rock > Andesite

Nearby scientific data

(1) -113.38544, 28.05579

Economic information

Comments on the geologic information

  • GEOL.COM: COUNTRY ROCKS DOMINANTLY ANDESITE PORPHYRY, BRECCIA AND ASSOCIATED VOLCANICS CORRELATIVE WITH ALISTOS FORMATION. INTRUDED BY QUARTZ MONZODIORITE PORPHYRY BODIES AND POST-MINERAL DIABASE DIKES. POST-MINERAL REGIONAL METAMORPHISM TO GREENSCHIST FACIES DATED AT A93 M.Y..

Economic information about the deposit and operations

Development status Past Producer
Commodity type Metallic
Deposit size Large
Significant No
Discovery year 1968

Mining district

District name Calmalli

Ownership information

  • Type Owner
    Owner Industria Minera Mexico, S. A.

Reserves and resources

  • Type In-situ
    Estimate year 1978
    Total resources 6000000mt ore
    Commodity Subtype Grade units Group Importance Year
    Copper Cu 0.6 wt-pct Copper Major 1978

Comments on the reserve resource information

  • CALCULATED AT CUT-OFF GRADE OF 0.4% CU. DOES NOT INCLUDE SMALL TONNAGE OF HIGH-GRADE ORE FROM TRANSITION ZONE BENEATH OXIDE LAYER.

Reference information

Bibliographic references

General comments

Subject category Comment text
Deposit METAMORPHOSED PORPHYRY COPPER DEPOSIT. PRIMARY MINERALIZATION CONSISTS OF PYRITE, CHALCOPYRITE, BORNITE, MOLYBDENITE, MINOR MAGNETITE AND GOLD DISSEMINATED IN FRACTURES AND IN QUARTZ-KSPAR-CALCITE-CHLORITE-EPIDOTE VEINLETS (A3 MM WIDE). PYRITE:CHALCOPYRITE RATIO 1.3 TO 1 IN CENTRAL CORE, WITH INTERNAL SUBZONES OF 0.5 TO 1. GRADES OUTWARD TO 14:1 IN PYRITIC HALO SURROUNDING QMP INTRUSIVE. CAPPED BY GOETHITE LAYER AVERAGING 40 M THICK (MAX. 60 M). OXIDATION MINERALS: CHRYSOCOLLA, GOETHITE, HEMATITE, CLAY MINERALS, NEOTOCITE, DIOPTASE, AND MALACHITE. HIGH-GRADE TRANSITION ZONE 9 M THICK BELOW OXIDE ZONE CONTAINS BORNITE, CHALCOCITE, COVELLITE, DIGENITE, CUPRITE, AND NATIVE CU. LIMITED DISTRIBUTION OF GOLD.

Reporter information

Type Date Name Affiliation Comment
Reporter 01-JUL-1987 Staude, John-Mark G. (Page, Norman J.) U.S. Geological Survey
Updater 01-JUN-1988 Leonard, Kenneth R. U.S. Geological Survey

Beyond USGS

Supplemental information added by qvyshift.com. Not part of the original USGS MRDS record.