PGC Logo Learning from Rocks & Mines
Super Porphyry 2003 - 04
Super Porphyry Cu/Au Deposits of the World
Photo Index
In the Grasberg pit and surrounds

In the Grasberg Pit  -   Upper left:  Looking across the upper eastern benches to the Carstensz Glacier (white splash on the highest upper left horizon) below the peak of the 4884 m mountain, Puncak Jaya, which is concealed in the cloud behind. Puncak Jaya is the highest mountain between the Himalayas and Andes, and from 7 km to the ESE, looms over the Grasberg pit. The permanent Carstensz Glacier, just 4° south of the Equator, can be seen glittering from the Arafua Sea to the south and attracted the attention of early explorers. In 1936 a young Dutch geologist, Jean Jacques Dozy, who was a member of an expedition to be the first to climb Puncak Jaya, noted en route, the unusual magnetic, high grade copper mineralisation that formed a small mountain he named Ertzberg, rising from an alpine swamp. He also, in passing described a nearby rounded grassy hill, devoid of trees, that he named Grasberg. Dozy published a report on these discoveries on his return to the Netherlands in 1939, but because of its remoteness and the onset of World War II, it received little attention. This report came to the notice of Forbes Wilson, the Freeport Sulphur Exploration Manager on a trip to Europe in the late 1950s. It piqued his interest, prompting him to gain management approval to mount an expedition to Papua to inspect the Ertzberg in 1960, culminating in production commencing in 1972.

  Upper right:   Looking across the >2 km wide Grasberg pit. Lower right:  Widodo Margotomo of Freeport (centre, holding plan) points out aspects of the geology of the orebody to Stuart Hayward (Newcrest Mining - Australia), Liu Jianbing (Ivanhoe Mines - China), Peter Pelly (BHP Billiton - South Africa) and Colin McMillan (Newcrest Mining - Australia).   The group then studied mineralised and altered breccias and intrusives within the Grasberg Igneous Complex at a range of selected locations.

The pit visit was followed later in the day by briefings on both mine exploration and the geology of the underground deposits to be visited next day.

Photographs by Mike Porter

MASTER ALBUM INDEX | PorterGeo Home | More on This Tour | Other Tours

Another PGC International Study Tour
Developed & Managed by Porter GeoConsultancy