|Latitude & Longitude (WGS84):||22° 25' 20'' South , 117° 20' 15'' East|
|Latitude & Longitude (decimal):||-22.42238,117.33775|
|Owned/operated by:||Rio Tinto Group (100%)|
|Köppen climate type:||BWh : Hot deserts climate|
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.
Commodity ListThis is a list of exploitable or exploited mineral commodities recorded at this locality.
1 valid mineral.
Rock Types Recorded
Select Rock List TypeAlphabetical List Tree Diagram
Entries shown in red are rocks recorded for this region.
This geological map and associated information on rock units at or nearby to the coordinates given for this locality is based on relatively small scale geological maps provided by various national Geological Surveys. This does not necessarily represent the complete geology at this locality but it gives a background for the region in which it is found.
Click on geological units on the map for more information. Click here to view full-screen map on Macrostrat.org
0 - 2.588 Ma
Age: Pleistocene (0 - 2.588 Ma)
Comments: regolith; synthesis of multiple published descriptions
Reference: Raymond, O.L., Liu, S., Gallagher, R., Zhang, W., Highet, L.M. Surface Geology of Australia 1:1 million scale dataset 2012 edition. Commonwealth of Australia (Geoscience Australia). 
2500 - 2800 Ma
|Archean sedimentary and volcanic rocks|
Age: Neoarchean (2500 - 2800 Ma)
Stratigraphic Name: Fortescue Group
Comments: Hamersley Basin
Reference: Chorlton, L.B. Generalized geology of the world: bedrock domains and major faults in GIS format: a small-scale world geology map with an extended geological attribute database. doi: 10.4095/223767. Geological Survey of Canada, Open File 5529.