South Windarra was mined intermittently by WMC between 1974 and 1992 using a combination of open-cut and underground mining techniques. A total pre-mining resource size of 6 million tonnes of ore @ 1.39% Ni for 83,405 tonnes of contained nickel metal was defined by WMC at South Windarra. Records show that 3 million tonnes of ore at 1.40% Ni was mined from the South Windarra Deposit, producing a total of 41,301 tonnes of nickel.
Poseidon has completed an evaluation of the remaining mineralisation at South Windarra which was identified and left behind by WMC. A reinterpretation of the geology and mineralisation trends at South Windarra led to a new understanding in the direction of the lava channel which hosts the nickel deposit. Poseidon believes the nickel bearing channel trends shallowly eastwards rather than steeply southwards as interpreted by WMC (diagram below).
Poseidon completed a ground seismic analysis to assist with the location of the potential extension to the South Windarra ore body in early 2011. Poseidon believes that significant evidence exists for an extension of the mineralisation, which would provide additional concentrator feed in future years. South Windarra includes a small residual resource at the base of the existing pit which is not believed to be significant and an eastern extension to the pit (identified by WMC) which is believed to demonstrate the trend of the main ore channel.
Poseidon Nickels reinterpretation determined that there was limited potential to continue mining below the existing workings. Subsequently the company commissioned an independent scoping mining study of the remnant nickel resources below the South Windarra pit and underground workings to determine if the South Windarra pit was suitable for in-pit tailings disposal of the generated tailings waste from the proposed nickel concentrator at Mt Windarra. This evaluation of the resource at the base of the pit determined that the pit is suitable to be used as an in-pit tailings dam, with the tailings being pumped via a pipeline from Windarra and deposited into the flooded pit.
The East Lode mineralisation remains accessible as it is separated from the mined out South Windarra ore bodies and is open for exploration down plunge, towards the east. The in-pit tailings will sterilise the remnant nickel resources below the South Windarra pit and underground workings as well as an area to the west of the South Windarra pit, however the East Lode remains in the company’s Resource Table under the South Windarra Project (See under Facts & Figures). The JORC compliant resource estimation for the East Lode is 772,000t @ 0.98% Ni for 7,500 tonnes of nickel metal at a 0.8% cut-off grade.