|Latitude & Longitude (WGS84):||31° 10' 43'' South , 121° 39' 0'' East|
|Latitude & Longitude (decimal):||-31.17885,121.65010|
|Köppen climate type:||BSk : Cold semi-arid (steppe) climate|
A nickel mine located a few km N of Kambalda. Part of the McMahon Complex, containing the Ken, Gellaty, Gordon, Wroth and Loreto shoots, all accessed via the McMahon decline. The McMahon deposit itself is central to these. No outcrop. Discovered 1968. Ore production began late 1972.
The komatiite flow in the area is 50 metres thick, increasing to 150 metres deep in an area called McMahon Deeps to the north-west.
The Footwall is metabasalt, ultramafics, and metasediments. The ultramafic host is foliated talc, dolomite, chlorite for the Hanging Wall ore, and talc-magnesite, chlorite rock for the contact ore.
The deposit contains two shoots called the upper McMahon Hanging Wall 350 metres by 170 metres, and lower McMahon Deeps as a narrow trough like structure, with several smaller deposits across 600 metres by 100 metres. Both trend north north-west. As the name suggests, McMahon Hanging Wall is entirely hanging wall ore, with McMahon Deeps contact ore and under 10% hanging wall ore.
McMahon Hanging Wall is Ni ore interleaved and in contact with sulphidic metasediments, which forms the Footwall. McMahon Deeps contains patchy mineralisation, best at its southern end.
McMahon Hanging Wall contains supergene pyrite, violarite, with minor chalcopyrite, marcasite, magnetite, chromite, and gersdorffite, grading 7-12% Ni.
McMahon Deeps contains primary ore of pyrrhotite, pentlandite, pyrite, chalcopyrite, and spinel grading at 10% Ni.
Commodity ListThis is a list of exploitable or exploited mineral commodities recorded at this locality.
13 valid minerals.
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
2500 - 4000 Ma
|mafic extrusive rocks 74248|
Age: Archean (2500 - 4000 Ma)
Description: Basalt, high-Mg basalt, minor mafic intrusive rocks; some andesite; agglomerate; mafic schist; amphibolite; dolerite; komatiitic basalt; carbonated basalt; basaltic andesite; mafic rock interleaved with minor granitic rock
Comments: igneous mafic volcanic; igneous mafic intrusive; synthesis of multiple published descriptions
Lithology: Igneous mafic volcanic; igneous mafic intrusive
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). 
|Neoarchean - Mesoarchean|
2500 - 3200 Ma
|Archean sedimentary rocks|
Age: Archean (2500 - 3200 Ma)
Comments: Yilgarn Craton
Lithology: Sedimentary rocks
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.