The Grasberg minerals district is a copper, gold, and silver porphyry skarn deposit located in the remote highlands of the Sudirman Mountain Range in the eastern province of Papua, Indonesia, on the western half of the island of New Guinea. The district includes the following operating underground mines: Grasberg Block Cave (GBC), Deep Mill Level Zone (DMLZ), and Big Gossan (BG). The Grasberg minerals district also includes Kucing Liar (KL), which began development in 2021. The Deep Ore Zone (DOZ) ceased production at the end of 2021 and Grasberg open-pit (GRS_OP) in 2019.

The ore bodies are located within and around two main igneous intrusions: the Grasberg monzodiorite and the Ertsberg diorite. The host rocks of these ore bodies include both carbonate and clastic rocks that form the ridge crests and upper flanks of the Sudirman Range and the igneous rocks of monzonitic to dioritic composition that intrude them. The igneous-hosted ore bodies (GBC, and portions of the DMLZ) occur as vein stockworks and disseminations of copper sulfides, dominated by chalcopyrite and to a lesser extent bornite. 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 Grasberg minerals district is situated on the crest of the Jayawijaya mountain range at elevations over 2,000 meters with the highest peak, Puncak Mandala at 4,760 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 in the district, all occurring 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;
- BG;
- KL (development stage mineral reserve);
- Dom (classified as mineral resource).

The sedimentary rock units of the Grasberg minerals district are classified into the two main groups:

- Kembelangan Group is approximately 3,400 meters thick, consists largely of siliciclastic rocks,
and is divided into four formations:
- Middle to Upper Jurassic Kopai;
- Upper Jurassic to Lower Cretaceous Woniwogi;
- Lower to Middle Cretaceous Piniya;
- Upper Cretaceous Ekmai.

- New Guinea Limestone Group is approximately 1,700 meters thick, is carbonate dominated, and divided into four formations:
- Paleocene Waripi;
- Eocene Faumai;
- Oligocene Sirga;
- Upper Oligocene to Middle Miocene Kais.

There are two main intrusive bodies in the district: the GIC and the Ertsberg diorite. Mineralization occurred in a short timeframe between 2.5 to 3.5 million years, shortly after the emplacement of the metal-laden associated igneous rocks. All the porphyry and skarn copper ore bodies in the area contain gold and silver as additional metals. The structurally controlled porphyry systems in the district are derived from potassium-rich magmas, dioritic to monzonitic in composition. Exoskarn and associated mineralization is mainly present in the New Guinea Limestone Group rocks, particularly within the dolomite of the Waripi formation, but also within the Cretaceous Ekmai limestone and sandstone

All of the currently active operations are underground mines. The mining method for each reserve is as follows:
- GBC: block/panel cave mine.
- DMLZ: block/panel cave mine.
- BG: open stope mine.
- KL: block/panel cave mine.

Mine unit operations include drilling, blasting to develop access, undercuts, drawbell development, ore raise development, drawpoint development, cave initiation, as well as loading and hauling. Support equipment is used for maintaining underground access roads, underground crushers, conveyors, and other mine services.

Required underground mining equipment varies by individual operation and includes that equipment required to develop and construct the mines as well as production support. The primary mining fleet consists of load-haul-dump loaders with 11 metric ton capacity and haul trucks with 55 to 60 metric ton capacity.

The site infrastructure at PT-FI has been established over the history of the project and supports the current operations. The current major mine infrastructure includes: waste rock storage facilities, temporary stockpiles, riverine tailings management system, power and electrical systems, water usage systems, various on-site warehouses and maintenance shops, and offices required for administration, engineering, maintenance and other related mine and processing operations.

Grasberg Block Cave Underground Mine
The Grasberg Block Cave ore body is the same ore body historically mined from the surface in the Grasberg open pit. Undercutting, drawbell construction and ore extraction activities in the Grasberg Block Cave underground mine continue to track expectations. Monitoring data on cave propagation in the Grasberg Block Cave underground mine is providing confidence in growing production rates over time. As existing drawpoints mature and additional drawpoints are added, cave expansion is expected to accelerate production rates to an average of over 105,000 metric tons of ore per day in 2022 and 122,000 metric tons of ore per day in 2023 from five production blocks spanning 335,000 square meters. As of December 31, 2021, the Grasberg Block Cave underground mine had 336 open drawbells.

The Grasberg Block Cave fleet consists of approximately 580 pieces of mobile equipment. The primary mining equipment directly associated with production and development includes an available fleet of 88 LHD units and 33 haul trucks. Each production LHD unit typically carries approximately 11 metric tons of ore and transfers ore into the rail haulage system. The Grasberg Block Cave has a rail haulage system currently operating with 10 locomotives and 120 ore wagons that haul the ore to the first 2 of the 3 planned gyratory crushers located underground via an automated rail system. Each ore wagon typically carries 30 metric tons.

DMLZ Underground Mine
The DMLZ ore body lies below the DOZ underground mine at the 2,590-meter elevation and represents the downward continuation of mineralization in the Ertsberg East Skarn system and neighboring Ertsberg porphyry.

The DMLZ has continued its ramp-up of production. Hydraulic fracturing operations have been effective in managing rock stresses and pre-conditioning the cave following mining-induced seismic activity experienced from time to time. Ongoing hydraulic fracturing operations combined with continued undercutting and drawbell openings in the two currently active production blocks are expected to expand the cave, supporting higher production rates that are expected to average approximately 68,000 metric tons of ore per day in 2022 and 69,000 metric tons of ore per day in 2023 from three production blocks. As of December 31, 2021, the DMLZ underground mine had 174 open drawbells.

The DMLZ fleet consists of over 390 pieces of mobile equipment, which includes 63 LHD units and 34 haul trucks used in production and development activities. Each production LHD unit typically carries approximately 11 metric tons of ore and transfers ore into the truck haulage system. The haul trucks have a capacity of 55 to 60 metric tons and load ore from chutes fed by the LHDs and transfer it to one of two gyratory crushers. The crushed ore is conveyed to surface stockpiles for processing.

Big Gossan Underground Mine
The Big Gossan ore body lies underground and adjacent to the current mill site. It 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 mine utilizes a blasthole stoping method with delayed paste backfill. Stopes of varying sizes are mined and the ore dropped down passes to a truck haulage level. Trucks are chute loaded and transport the ore to a jaw crusher. The crushed ore is then hoisted vertically via a two-skip production shaft to a level where it is loaded onto a conveyor belt. The belt carries the ore to one of the main underground conveyors where the ore is transferred and conveyed to the surface stockpiles for processing.

The Big Gossan fleet consists of over 90 pieces of mobile equipment, which includes 14 LHD units and 10 haul trucks used in development and production activities.

Kucing Liar Underground Mine
PT-FI commenced long-term mine development activities for its Kucing Liar deposit in October 2021, which is expected to produce over 6 billion pounds of copper and 5 million ounces of gold between 2028 and the end of 2041. The Kucing Liar underground deposit lies on the southern flank of and underneath the southern portion of the Grasberg open pit at the 2,605-meter elevation level. Similar to PT-FI's experience with large-scale, block-cave mines, pre-production development activities will occur over an approximate 10-year timeframe. At full operating rates of 90,000 metric tons of ore per day, annual production from Kucing Liar is expected to approximate 600 million pounds of copper and 500,000 ounces of gold, providing PT-FI with sustained long-term, large-scale and low-cost production. Capital investments for Kucing Liar over the next 10 years are expected to average approximately $400 million per year. Kucing Liar will benefit from substantial shared infrastructure and PT-FI's experience and long-term success in block-cave mining.

Crushing and grinding facilyties consists of:
- Underground primary crusher where it is crushed and then conveyed to coarse ore mill stockpiles that feed the concentrators.

- Concentrators 1 and 2 or the North/South concentrators that include 2 secondary crushers, followed by 8 tertiary crushers in closed circuit with screens, then 2 HPGRs in quaternary crushing duty, followed by 8 ball mills;

- Concentrator 3 or the SAG1 concentrator which includes SAG mill in closed circuit with a pebble crusher followed by 2 parallel ball mills for size reduction;

- Concentrator 4 or the SAG2 concentrator which includes SAG mill in closed circuit with 2 pebble crushers followed by 4 parallel ball mills.

The concentrator facilities located at MP74 are at an elevation of 2,800 to 2,900 meters above sea level and approximately 110 kilometers from the portsite dewatering and shipping facilities. The concentrators treat primary crushed ore conveyed from underground mines to surface stockpiles at MP74.

The first processing facilities treating Ertsberg pit ores were commissioned in 1973 and have seen incremental capacity enhancements over the years. Ore is processed in the mill, which produces a copper concentrate by flotation. Ore is delivered from the mine to an underground primary crusher where it is crushed and then conveyed to coarse ore mill stockpiles that feed the concentrators. Ore is conveyed from the mill stockpiles to the copper concentrators.

Ore enters the C1/C2 concentrator, where the secondary crushers accept scalped feed and are followed by a tertiary crushing circuit operating in closed circuit with vibrating screens, which provide the initial size red ........