1936 - Colijn expedition, including Jean-Jacques Dozy, is the first outside group to reach the Jayawijaya mountain glacier and discover Ertsberg.
1960 - Freeport expedition, led by Forbes Wilson & Del Flint, explores Ertsberg.
1963 - The Dutch transfer Netherlands New Guinea to the United Nations, who in turn delivers it to Indonesia. Mining project plans are shelved due to the policies of the Soekarno regime.
1970 - Full-scale project construction begins.
1972 - The first trial shipment of Ertsberg copper concentrate is exported.
1980 - GBT Underground Mine becomes operational.
1985 - Additional underground copper deposits discovered under the GBT underground mine.
1990 - Construction work continues on expansion to 52,000 t/d.
1991 - New Contract of Work with a 30-year term and two 10-year extensions is signed with the Government of Indonesia. By year-end, reserves total almost 770 million metric tons.
2000 - Memorandum of Understanding on socio-economic resources, human rights, land rights, and environmental rights announced by leaders of LEMASA (Amungme people’s organization), LEMASKO (Kamoro people’s organization) and PTFI. DOZ underground mine development begins. Record copper production of over 1.64 billion pounds of copper.