Nammuldi Mine (Nammuldi Group), Mount Brockman, Ashburton Shire, Western Australia, Australiai

Regional Level Types
Nammuldi Mine (Nammuldi Group)	Mine
Mount Brockman	Mountain
Ashburton Shire	Shire
Western Australia	State
Australia	Country

Nammuldi is an iron ore mine owned by Rio Tinto, and operated by its fully owned subsidiary Hamersley Iron Pty Ltd. Rio operates twelve iron ore mines in the Pilbara. The mine is 60 kilometres north-west of Tom Price, and produces 6.6 million tonnes of ore per annum. It started in 2006, with an expected life-span of 10 years. At Nammuldi are Pits A, B, C/D, E and F, which all access the Marra Mamba Formation, and near Pit F which mines detrital material. The mine is very near the Brockman 2 iron ore mine, and Silvergrass iron ore mine. Silvergrass contains Range Pit, Valley Pit, Flats Pit, all mining the Marra Mamba Formation, with an expected mine life-span of 7 years. Both mines access ore below the water table.

The mine is located in the 80 000 square kilometres Hamersley Iron Province, aged 2500 million years old (late Archaean to early Proterozoic)as rock formations known as the Hamersley Group. They have been formed by the chemical sedimentation of minerals in an ocean environment. Volcanic activity introduced basalts, and rocks like sandstone have developed from weathering, and the transportation of rocks when the area was being formed.

Layers of rocks have been deposited with different chemical compositions, some iron rich, alternating with silica rich rocks, and the occassional sedimentary layer. The Hamersley Group is 2.5 kilometres thick and contains banded iron formation units, being iron mineralisation of magnetite, hematite and gangue minerals such as carbonates, silicates and cherts.

The banded iron formations include the Brockman Iron Formation (620 metres thick), and the Marra Mamba Iron Formation (230 metres thick), with the latter being older and located under the Brockman formation. These formations have been enriched by iron which can make-up over 60% of the formation.

In the Brockman Formation the units are from lowest: Dales Gorge Member, Whaleback Shale, Joffre Member, and Yandicoogina Shale Member. Hematite is the dominant species with some goethite. The Marra Mamba Iron Formation is composed of more goethite than hematite compared to Brockman.

The Marra Mamba entry on Mindat is referring to some small specimen mines near Mt Brockman, in the same area, where Tiger Eye has been obtained. The original entry for Nammuldi listed it as a shaft. No historic reference could be found, and could be referring to the drill-holes during exploration by Rio of the deposit. The mines are large open-cut operations.

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