Bronzewing Mine (Bronzewing-Mount McClure Mine), Yandal Station, Leonora Shire, Western Australia, Australia

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The Bronzewing Gold Mine is located 83 kilometres north-east of Leinster, and was discovered by prospector Mark Creasy. He sold the lease to Great Central Mines for $115 million, earning him an entry into the Guiness Book of Records for the prospector with the richest payout for a mineral discovery. Part of this money was used to buy significant collections of Western Australian minerals, including the Borner Collection and Blair Gartrell Collections. These he donated to the Western Australian Museum and Kalgoorlie's Miners Hall of Fame. Information on Mark's life can be found by visiting the Miners Hall of Fame.

After initial strong gold recoveries, the mine has had a somewhat chequered ownership history. The mine opened in 1991. Great Central Mines was taken over by Normandy Mining in 1999, then in turn taken over by Newmont Mining Corporation in 2002. Between 1991 and 2004 the mine produced 3 million ounces of gold from eleven open cuts and two underground operations.

View Resources purchased the mine in 2004, and initially placed it under care and maintenance, before re-opening it again in 2007. Ore was mined from two pits (Success and Central), and two underground declines (Discovery and Calista). By 2008 gold recoveries were below expectations, and View Resources eventually went into liquidation. Navigator Resources purchased the mine in 2009, with mining starting the following year, but again gold recoveries were below expectation.

The mine is located in the Yandal Greenstone Belt, 250 kilometres long by 40 kilometres wide. The Belt also holds the Jundee and Darlot mines, along with several other smaller mines and prospects. As the mine is located in the Bates Creek drainage area, the surface contains a significant amount of alluvium 80 to 120 metres in depth from the surface. It contains ferro-saprolite grading to saprolite lower down, composed of kaolinite, smectite and quartz. The ferruginous saprolite is yellow brown to red brown in colour, dominated by kaolinite and goethite. Mottled saprolite further down is red hematite pseudomorphing other minerals. The saprolite also contains iron nodules, quartz, clay and silt. Relict chlorite, feldspars, calcite, mica and pyrite are also found in more minor amounts. Gold is found in the lower levels of the alluvium. Copper, silver and tungsten is also found but appears to have no direct relationship to the gold.

Fresh rock is encountered 80 to 120 metres from the surface. It contains iron rich tholeiitic basalts and dolerite units, with lesser ultramafic, felsic and sedimentary sequences. The area shows early thrusting following by three stages of deformation, with gold mineralisation associated with the final deformation stage. The high iron content of the host rocks favours the formation of iron sulphides caused by iron from the wall rock, with sulphur from the mineralising solution. The loss of this sulphur causes destabilization of the gold-sulphur complex leading to the precipitation of gold. The tendency of the host rock to fracture easily when subjected to water pressure also contributes to the high gold grades of these deposits.

Gold is found in association with quartz veins and pillow basalts. While the veins are sulphide poor, locally abundant pyrite has been found, with pyrrhotite, minor chalcopyrite, scheelite and visible gold. The deposit contains little in the way of supergene enrichment.

Mineral List

Actinolite Albite Ankerite 'Biotite' Calcite

Chalcopyrite 'Chlorite Group' Dolomite Epidote Gold

Ilmenite Magnetite Muscovite Pyrite Pyrrhotite

Quartz Rutile Titanite

18 entries listed. 16 valid minerals.

References