Koolyanobbing, Yilgarn Shire, Western Australia, Australiai

Regional Level Types
Koolyanobbing	- not defined -
Yilgarn Shire	Shire
Western Australia	State
Australia	Country

The name comes from the local aboriginal language meaning 'place of large rocks', which is apt for an iron ore mine.

The mine is located 54 kilometres north north-east of Southern Cross.

The first non-aboriginal person to explore the area was gold prospector Henry Dowd in 1887 and 1891. He was rather unimpressed with the rocks seen, but placed some in a bottle anyway, and buried it by a survey peg at what would later be known as Dowd or Dowd's Hill. The bottle was discovered in 1963.

Mining first took place by the Western Australian Government in 1948, supplying iron ore to its charcoal iron plant at Wundowie.

Geological surveys in 1952 identified significant iron ore. Dampier Mining (a subsidiary of BHP) mined iron ore here between 1967 to 1983. The ore was railed to its steel blast furnace at Kwinana, south of Perth.

Mining recommenced in 1993 by Portman Mining, which was taken over by Cliffs Natural Resources in 2008, who have continued mining. Ore is railed to the port of Esperance. They also mine iron ore at Mt Jackson and Windarling Range to the north of Koolyanobbing.

Dowd's Hill is the largest of five mining areas extending south along the Koolyanobbing Range. It is hosted by a 60 kilometre long north north-west trending greenstone belt, truncated west, north and south by the Koolyanobbing Fault.

The dominant rock is fine to medium grained actinolite amphibolite, with thin discontinuous bands of chert, banded quartzite, and banded iron formations. The latter is composed of banded magnetite schist and quartz-magnetite, which is turn contains siderite, and massive pyrite with hematite, minor magnetite, and graphite.

Dowd's Hill is the largest deposit, 900m long by 50-300m wide and 50-80m deep from the surface. The ore is massive hard goethite, course grained friable specular hematite, massive fine grained hematite, ochrous yellow limonite, minor magnetite, bands of chlorite schist, and friable iron leached jaspilite.

Specimens from the mine were once thought rare. Across 2010-2011, local collector and specimen miner, Fred Rose, sold about four dozen specimens, which are now in private collections. These variously covered fine grained, iridescent and botryoidal goethite, bladed specularite, hematite mica, micro magnetite crystals, some on ironstone and banded iron formation matrix.

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