Cosmos’ cluster, or ‘camp’ of nickel sulphide deposits, occurs within or adjacent to a local sequence of ~2.7 billion year (Ga) old (Archean age), and now metamorphosed, komatiitic lavas that are part of the Agnew-Wiluna Greenstone Belt (AWGB) of the Kalgoorlie Terrane of the Eastern Yilgarn Craton.

The genetic formation model for the nickel mineralisation is the ‘Kambalda-style’ model where precipitation of nickel sulphides is interpreted to occur in channelised komatiitic lava flows and/or lava tubes. This model proposes two dominant deposit types – Type 1 and Type 2.

‘Type 1’ deposits are interpreted to have formed where the hottest lava in the centre of a lava channel thermally erodes into a sulphidic substrate and massive sulphides accumulate at the channel’s base. This high-grade primary formation style is applicable to the Cosmos, Cosmos Deeps, AM1, AM2, parts of AM5 and the Odysseus Massive zones.

Type 1 deposits are often subject to mobilisation into structural sites when massive sulphide bodies behave plastically or even re-melt under the high metamorphic temperatures and pressures that are generated by local or regional tectonic faulting and/or folding events. The Cosmos Deeps and the Odysseus Massive zone are examples of this remobilisation style.

‘Type 2’ deposits are interpreted to have formed from cooler and slower-flowing lavas than those for Type 1 deposits. In this model, the mineral olivine is envisaged to cryst ........

Cosmos Nickel Complex is located 30km north of Leinster and include high grade deposits at Cosmos, Cosmos Deeps, Prospero, Tapinos, AM1, AM2, AM4 and Odysseus North Massive Sulphide, medium grade deposits at AM5 and AM6 and large low-grade Mt Goode deposit.

The Cosmos Project comprises the development of the Odysseus underground mine focused on the production of nickel concentrate. First production expected mid-2023.

WSA’s(Western Areas Limited) 2018 FS was a detailed analysis that confirmed the technical feasibility and economic viability of a 10-year underground mine at Odysseus based on the assumption of an average 0.9Mt/a of processing to produce ~14.6kt/a of a 16.5% Ni saleable concentrate. This production target was based on the 8.14Mt grading 2.02% Ni designed to be extracted from the Odysseus 2018 MRE discussed above. Processing was targeted to commence from October 2022, with a ramp up to full production in FY24. The FS also considered the inclusion of AM6 to extend the mine life, with a subsequent PFS confirming the Ore Reserves for AM6.

IGO is in the process of implementing an optimisation strategy and plan for the project. This will involve expanding the scope of the project along with de-risking some elements of what was originally planned. These changes include:
- coupling completion of the shaft with that of the processing plant;
- completion of additional underground mining development to create multiple working areas ........

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