Whim Creek Copper Mine (Whim Creek Copper prospect; Whim Well Mine), Whim Creek, City of Karratha, Western Australia, Australiai

Regional Level Types
Whim Creek Copper Mine (Whim Creek Copper prospect; Whim Well Mine)	Mine
Whim Creek	Creek
City of Karratha	Shire
Western Australia	State
Australia	Country

A copper mine located near the North West Coastal Highway between Roebourne and Port Hedland. Most of the specimens in collections were collected in 1985, mainly malachite, chrysocolla and golden crystals of wulfenite. Little material has been available since.

Copper mineralisation was discovered here in 1887 by prospector Phillip Saunders. Mining at the deposit has been sporadic. Minor production occurred from 1891-1893 by the Bateman Syndicate, and 1898-1901 by Preli & Co. Both closed due to the high cost of production and low copper prices. More substantial mining took place between 1906-1924 by Whim Well Copper Mines Ltd, later re-named Pilbara Copper Fields Ltd producing 67,177 tonnes of ore. Mining ceased at this time when the bulk of the near-surface secondary ore had been exhausted. Mining resumed in 1949 for copper as a fertilizer but ceased again in 1959. In 2003 large-scale mining of the deposit took place by Straits Resources and later BHP Billiton.

Whim Creek is a Cu-Zn-Pb-Ag deposit. Several small sulphide deposits formed in the area from volcanics and trough sedimentation in basins, which in turn were formed by oblique slip fault zones. The deposit initially plunges 20-25 degrees to the northeast, before steepening to 50 degrees at its northern limit. Folding divides the deposit into western and eastern shoots.

The primary sulphide ore is cobaltian pyrite-pyrrhotite-chalcopyrite-sphalerite of a highly variable texture with minor galena, magnetite, and arsenopyrite. Fine-grained disseminated sulphide is more common than massive sulphide pods. Quartz, chlorite, and siderite can be intermixed with the latter. A number of other sulphide species can be found in minor amounts including galena, argentian tetrahedrite, arsenopyrite, bismuthinite, bismuth, stannite, cobaltite, and rutile. Cassiterite is common as rounded grains.

The supergene zone is 25 metres to 75 metres in depth. Early reports indicate chalcocite was prevalent. Other species include covellite, chalcopyrite, and sphalerite.

The oxidized zone starts at 25 metres, composed of goethite-hematite, kaolinite, quartz, and cassiterite. The semi-arid environment has promoted the retention of an abundance of secondary ore minerals in this zone.

How the minerals were formed in the deposit is poorly understood. This is because there is little information about where in the deposit the specimens were obtained and their geological relationship. Azurite was said to be common in the early days of mining, however, by the 1980s the main specimens available was azurite pseudomorphed by malachite, commonly encrusted by crystals of wulfenite. In some cases, chrysocolla has pseudomorphed both the malachite and azurite.

A 1980 report describes osarizawaite ring crystals, probably the first time this form was described for the species. It is thought the inner portions of the crystals dissolved later. The species was found on one gossan as encrustations barely visible to the naked eye, with the crystals only 5-10 micrometres in diameter. As a result, they have not been seen in private collections so far.

Other Regions, Features and Areas containing this locality

References