The resource now comprises 111 million tonnes at 889ppm cobalt-equivalent for 79,500 tonnes of contained cobalt at a 400ppm cobalt-equivalent cut-off.
Maiden measured resource
This includes a maiden measured resource of 8 million tonnes at 1,150ppm cobalt-equivalent for 17,100 tonnes of contained cobalt.
The update follows 9,500 metres of drilling completed in the fourth quarter of 2018 and first quarter of 2019 targeting the definition of a component of measured mineral resources.
Cobalt Blue’s CEO Joe Kaderavek said: “We are pleased with the improved classification achieved through the recent drilling campaign.”
He said 66% of the mineral resource was now available for potential conversion to proven and probable ore reserves.
Thackaringa’s previous estimate at a 500ppm cobalt cut-off was 72 million tonnes at 852ppm cobalt for 61,500 tonnes.
The infill drilling was aimed at enhancing geological confidence and data density and focused on the upper extent of the Pyrite Hill deposit, less than 200 metres from surface.
This deposit extends over 1.2 kilometres along strike and is drill tested to around 300 metres down dip.
Inputs derived from the Thackaringa pre-feasibility study have supported a revision of the resource cut-off grade from 500ppm cobalt to 400ppm cobalt equivalent.
Sulphur included in resource
This has resulted in the inclusion of elemental sulphur as a revenue stream, which has contributed to a “significant” increase in the resource.
The updated resource reflects a sustained exploration effort by COB with 30,000 metres drilled from 2016.
This has realised a 235% increase in resource tonnes and a 189% uplift in contained cobalt since COB issued its prospectus and became an independent company listed on the ASX.
“Strong record of resource growth”
Kaderavek said: “COB continues to maintain a strong record of resource growth with the update demonstrating a firm step toward realisation of COB’s plus-20-year mine life target.”
At Pyrite Hill deposit, the company’s drilling fleet navigated steep terrain to increase data density through the oxidation profile.
Drilling intersected variable zones of sulphide mineralisation intercalated with localised oxidation.
This provided sufficient constraint to include ‘transition’, or partially weathered, material for Pyrite Hill.
The campaign also allowed completion of an initial phase of drilling to test down-dip extensions of this deposit with holes intersecting mineralisation around 180 to 280 metres below surface.