Indonesia

Big Gossan Mine

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Categories

Overview

Mine TypeUnderground
Commodities
  • Copper
  • Gold
  • Silver
Mining Method
  • Blast Hole Stoping
  • Cemented paste backfill
Production Start... Lock
Mine Life2041
ShapshotThe Big Gossan mine is a part of Grasberg minerals district.

BG ore body lies underground and adjacent to the current mill site.
Related AssetGrasberg Complex

Owners

SourceSource
CompanyInterestOwnership
Freeport-McMoRan Inc. 48.76 % Indirect
PT Indonesia Asahan Aluminium (Persero) 51.24 % Indirect
PT Freeport Indonesia (operator) 100 % Direct
In Indonesia, PT Freeport Indonesia (PT-FI) operates in the Grasberg minerals district.

Freeport-McMoRan have a 48.76 percent share ownership in PT-FI and the remaining 51.24 percent share ownership is held by PT Indonesia Asahan Aluminium (an Indonesian state-owned enterprise).

Deposit type

  • Skarn
  • Sediment-hosted

Summary:

The Grasberg minerals district is situated on the crest of the Sudirman Mountain Range at elevations over 2,500 meters with the highest peak, Puncak Jaya at 4,884 meters. Ore deposits in the Grasberg minerals district have economic copper, gold, and silver mineralization in porphyries and skarns. The primary sulfide mineralization is chalcopyrite, with lesser bornite, chalcocite, and covellite. Gold concentrations usually occur as inclusions within the copper sulfide minerals although in some parts of deposits gold can also be strongly associated with pyrite.

There are five major ore bodies all within the center of the Grasberg minerals district:
• Grasberg Intrusive Complex (GIC) includes the GBC and the depleted GRS_OP.
• EESS includes DMLZ and depleted GBT, IOZ, DOZ block caves.
• BG.
• KL (development stage mineral reserve).
• Dom (classified as mineral resource).

The Big Gossan mine is a tabular, near vertical ore body with approximate dimensions of 1,200 meters along strike and 800 meters down dip with varying thicknesses from 20 meters to 120 meters.

The sedimentary-rock hosted ore bodies (portions of the DMLZ, KL and all of the BG) occur as “magnetite-rich, calcium/magnesian skarn” replacements, whose location and orientation are strongly influenced by major faults and by the chemistry of the carbonate rocks along the margins of the intrusions.

The copper mineralization in these skarn deposits is dominated by chalcopyrite, but higher bornite concentrations are common. Moreover, gold occurs in significant concentrations in all of the district’s ore bodies, though rarely visible to the naked eye. These gold concentrations usually occur as inclusions within the copper sulfide minerals, though, in some deposits, these concentrations can also be strongly associated with pyrite.

Reserves

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Mining Methods

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Comminution

Crushers and Mills

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Processing

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Production

Combined production numbers are reported under Grasberg Complex

Operational metrics

Metrics202320222021202020192018
Daily ore mining rate 000000000000
Daily milling rate 000000000000000000003,800 t

Production Costs

Commodity production costs have not been reported.

Heavy Mobile Equipment

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Personnel

Mine Management

Source Source
Job TitleNameProfileRef. Date
....................... Subscription required ....................... Subscription required Subscription required Feb 21, 2024
....................... Subscription required ....................... Subscription required Subscription required Feb 22, 2024
....................... Subscription required ....................... Subscription required Subscription required Feb 21, 2024

Aerial view:

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