The Cawse Extended Project which is currently under care and maintenance is operated by Mesmeric Enterprises Pty Ltd who hold at 80% interest in the project. TNG’s interest in the Cawse Extended Project is 20% free-carried to production, convertible at the Company’s election to a 2% net smelter return.
TNG believes that Cawse Extended will continue to be an important ore source for Norilsk in the long term and provide a potential cash flow for TNG Ltd.
The Cawse Extended Project is located approximately 65 km North West of Kalgoorlie in Western Australia and is immediately adjacent to the Cawse Nickel-Cobalt Operation.
To date, exploration on the Cawse Extended Project tenements has identified nine separate Ni laterite prospects.
The Cawse Extended Project tenements are on the western limb of the Goongarrie – Mt Pleasant anticline in the Ora Banda domain of the Kalgoorlie terrain.
Four main types of mineralisation have been identified at the Cawse Extended Project. These are the oxide ores of limonite, talc, and siliceous cobalt and the smectite-saprolite ore (locally termed nontronite). The identification of these ore types, their grade ranges and physical characteristics proved crucial in the subsequent metallurgical sampling due to their differing metallurgical properties.
Limonite mineralisation comprises approximately 75% of the global resource. Limonitic clays with variable proportions of vuggy, goethitic silica typically contain grades of 0.4% to 1.5% nickel. Nickel grade decreases as the proportion of silica increases. Cobalt content is between 0.01% and 0.3% at which point manganese staining of the silica occurs. The ore type is upgradeable by screening out the coarse silica fraction. This ore type comprises the bulk of the upgrade ore.
Siliceous cobalt (SICO) mineralisation comprises approximately 5% of measured resources. It occurs as 1 metre to 6 metre thick sub-horizontal layers in the upper 20 metres of the weathering profile. The ore is characterised by dark blue to black siliceous rock with abundant cobalt-rich manganese oxides such as todorokite, chalcophanite and cryptomelane, which carry cobalt grades from 0.3% to 7% and nickel grades from 0.5% to 5% in the rock mass. The ore is not upgradeable due to the association of nickel and cobalt to manganese, which is then associated to coarse chalcedonic silica.
Talc mineralisation comprises approximately 10% of the global resource and is located throughout the weathering profile proximal to penetrating talc-chlorite shear structures. It typically contains high nickel grades, generally between 1% and 2% and high magnesium levels between 8% and 15%.
2008 Cawse Extended JV Mineral Resource (depleted by production as at July 31, 2008).