The Windarra region forms part of the Mt Margaret Goldfield. Mafic and ultramafics, metavolcanics and intrusives form important members of the Windarra greenstone belt. A major granitoid pluton has intruded the stratigraphy and has locally stoped out the main BIF. Mafic-ultramafic and BIF xenoliths thought to be stratigraphically equivalent to the Windarra sequence occur within the granites in the region.

The Windarra BIF is the lowest recognisable stratigraphic unit in the Margaret sector. The overlying ultramafic rocks host both the Mt Windarra and South Windarra nickel deposits and represent the base of the first cycle of ultramafic to mafic volcanics. It is the only ultramafic cycle in the region known to host economic nickel mineralisation. Three volcanic cycles are recognised in this sector with the rocks of the uppermost being overlain by conglomerate along the western margin of the Laverton tectonic lineament.

Mine Geology
The Mt Windarra nickel occurs towards the bottom of a thick ultramafic sequence at the base of the first volcanic cycle. Granular quartz-feldspar rocks in the Mt Windarra mine area may represent metamorphosed sandstone. The Windarra (Main) banded iron formation constitutes the base of the exposed stratigraphy, and the immediate footwall to mineralisation at South Windarra. The unit is an 80m to 150m thick sequence of siliceous and banded chemical sediments, containing variable amounts of quartz, grunerite, actinolite, mag ........

The underground mine at Windarra includes an underground crushing station at approx 450m depth with a horizontal shaft for hauling ore to the surface. Ore is crushed underground in a crushing station at the 450m level. The mining method used is sub level caving, which is amongst the most economic methodologies available and is suitable for this style of resource, was used at Mt Windarra for the last several years of operation and has been selected as the preferred method for the future. The cost of mining compares favourably with Kambalda style nickel mine and is similar to sub level cave mining costs in other locations in Australia, notably the Savannah nickel mine in northern WA.

Ore is crushed underground in a crushing station at the 450m level.

The combined ore feed (Cerberus and Mt Windarra ores) will be processed in a 700,000 tonne per annum concentrator plant of standard configuration. The plant has been designed and is considered low risk with a construction period of approx 12 months. The processing plant includes facilities for cyanide treatment of the gold tailings reserve on the site which will be carried out in parallel with the nickel flotation. Final smelting of gold will be undertaken through toll treatment at Kalgoorlie and Perth. Poseidon does not need to invest in any substantial capital facilities outside of the project boundary, other than some highway access, as these are all available. This includes sealed haul roads to the rail head at Leonora and rail transport to the export ports of Esperance (bulk) or Fremantle (containerised). Substantial capacity exists on this rail line and quotations from mine gate to port have been recei ........