Telfer Mine, Rudall River District, East Pilbara Shire, Western Australia, Australiai

Regional Level Types
Telfer Mine	Mine
Rudall River District	Mining District
East Pilbara Shire	Shire
Western Australia	State
Australia	Country

A gold(-copper) mine located 500 km inland from Port Hedland, and about 80 km E of the Nifty copper deposit.
Owned by Newmont (70%) and BHP (30%) in 1984; by Newcrest Mining Ltd since 1990. Produced 117,000 ounces Au (1984).

Au-Cu deposit. Reef and stockwork domains in Proterozoic sediments, weakly metamorphosed, structurally deformed by folding and faulting and intruded by granites.
Famous for excellent chalcocite specimens.

Telfer is located in the Great Sandy Desert in the Paterson Province of Western Australia, approximately 450 kilometres east-south-east of Port Hedland. Telfer is approximately 1,300 kilometres by air and 1,900 kilometres by road from Perth.

The operation is comprised of two mines, Telfer Open Pit and Telfer Underground. Telfer Open Pit contains 2 open pits, Main Dome and West Dome. Open pit mining currently takes place in the Main Dome. The underground mine is located beneath the Main Dome open pit.

Situated in the Great Sandy Desert, the Telfer Au-Cu mine, is one of the most remote in the world. Some mineral specimen related literature on the internet note the mine is near Carnarvon. It is a very long walk from Carnarvon to the mine. Specimens are rare, as they are virtually all destroyed in the mining process. The deposit was discovered in 1971, and mining started in 1977. By the time it closed in 2000, 186t of Au had been produced. The closure was forced due to low prices, and problems the mine had in processing the low grade Au-Cu ore. Mining recommenced with an open pit in 2004 and then underground mining in mid 2006. The expected mine life of the open pit is 2023 and the underground workings 2015.

The ore bodies mined are hosted by the Telfer Formation, with the Malu Quartzite above, and the carbonate rich Puntapunta Formation below, within several other formations from the surface down. The Telfer Formation is mainly quartzites, sandstones and siltstones, 600-700 metres thick, and is aged late Mesoproterozoic to early Neoproterozoic.

The Telfer Formation contains a number of layers, from the base up:
2-5 m thick silicified siltstone with disseminated pyrite and siderite; 20-50 m poorly sorted quartz sandstone; 5-9 m fine grained siltstone, claystone, mudstone, minor carbonaceous limestone and calcareous sandstone with abundant pyrite and shortite pseudomorphs; 25-40 m fine grained quartz sandstone with silty or muddy interbeds; 1-4 m sideritic siltstone with minor fine grained sandstone and minor pyrite; 30-40 m stratified sequence of interbedded quartz sandstone and siltstone; 500 m well stratified calcareous and minor carbonaceous siltstones with interbedded sandstone; 10-90 m sandstone with pyrite.

Chalcocite is the main ore for the open pit, and chalcopyrite for the underground workings (Telfer Deeps). The mining area contains broad gentle domes, intruded by 680-620 Ma granitoids containing prophyry like Au-Cu, Au and W-Pb-Zn skarn mineralisation, and stratabound Au reefs.

These reefs are approximately 2 m thick, along the base of siltstone beds overlying a sandstone unit in the lower reaches of the Telfer Formation. The underground workings access at least eight main reefs. The supergene zone is 240-290 m below the surface and in some areas chalcocite has largely replaced pyrite. Mineralisation in the Main Dome extends to a depth of 1300 m, and 1500 m for the West Dome.

The main ore from the open pit was known as Middle Vale and E Reefs, being thin sheets of gold infused quartz-pyrite-chalcopyrite over a 20 square kilometre area. The primary minerals found are pyrite and quartz with gold, chalcopyrite, pyrrhotite, with minor bornite and chalcocite. Even more minor galena, sphalerite, scheelite, and Pb-Co-Ni sulphides. The pyrite could reach concentrations of up to 20% and extend 20-30 metres into the footwall as euhedral crystals in locally massive areas in quartz veins, or as course euhedral zones and fine grained mimicking the bedding structure of the host siltstones. Sericite, ankerite, dolomite, calcite, tourmaline and albite are said to be common.

In the 1990's, world class chalcocite crystals were found in what is known as the chalcocite blanket, which marks the present or past water table. The Western Australian Museum describes these as ranging from single crystals to clusters 6 cm across. A few are on a calcite matrix or are associated with calcite crystals. Cruciform twins, penetrating crystals and elongated prismatic crystals with arrowhead terminations are said to be common in the material they studied.

These crystals may never have come to the attention of the outside world if not for the actions of a miner working at the site. Figuring (probably correctly) they would be destroyed he removed a quantity, and then sold them to an Australian mineral dealer. These were sold at the 2001 Tuscon Show. A disagreement between two Australian mineral specimen dealers, resulted in the material being reported to Newcrest Mining, who called the police. The specimens were promptly withdrawn from sale. In 2004 the former employee faced court in Perth, and after a four day trial, the jury took one hour to acquit him of theft. The view of the court was the accused should be judged on the value of the material to Newcrest in its mining operations, that Newcrest would have destroyed the specimens in the mining process, which would have amounted to a few cents in metal content to the company. After the court case, Newcrest gave most of the specimens to Australian museums and some university geology departments. As such these chalcocite specimens are rare in private collections, being largely those bought in good faith, during the short time they were on sale.

Other Regions, Features and Areas containing this locality

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