Target Case Development
In 2015, 8000 metres of drilling was completed at D Zone and delivered a Scoping Study on a copper-only development scenario. The Scoping Study was updated in April 2016.
Future drilling will consider potential resource extensions with focus on the following zones;
- D Zone South – high grade shoot extension to depth
- D Zone Main – high grade shoot extension to depth
- A and B Zone Open pit infill – hangingwall and footwall zones
- A Zone depth extensions
Environmental and Social Impact Assessment activities have commenced and are premised on the re-opening of a former working mine to extract copper from extensions to known ore bodies.
It is envisaged that project execution time will be minimal due to the project’s proximity to well-established infrastructure. For example, no power station, camp, airstrip, or significant site access road will be required.
Production from a 2.0 million tonne per annum plant is expected to commence in 2020, subject to permitting.
The development opportunity envisages open-pit feed from A Zone and B Zone operating as a base load to be supplemented by high grade underground material with similar grades to that recovered historically. Additional open-pit and underground feed will be defined by the proposed resource extension drilling.
D Zone Underground
A drill program has been designed that aims to extend the D Zone Mineral Resource in several areas. The highest ranked targets are extensions to the high-grade, sub-vertical ‘shoots’ that were defined during the 2015 drilling program. There are currently 2 shoots, referred to as D Zone Main and D Zone South, as shown in Figure 2. These areas returned very strong results during 2015, including:
- 26.7m at 2.6% Cu, including 6.6m at 3.5% Cu and 5.2m at 2.9% Cu and 6.9m at 2.6% Cu, in VDD 193
- 21.5m at 1.5% Cu, including 3.0m at 2.3% Cu and 9.9m at 2.2% Cu, in VDD 195
- 9.4m at 2.0% Cu and 3.6m at 2.8% Cu, in VDD 186
- 10.4m at 1.6% Cu, including 5.3m at 2.0% Cu in VDD 196
Drilling to date had identified copper mineralisation to a depth below surface of 640m, but with a majority of that drilling only being to 480m on the Main shoot, and 300m below surface on the South shoot.
Several other targets also exist at D Zone and include other potential sub-vertical shoots to the north and south of these existing shoots.
The host rock to the copper mineralisation at D Zone is a magnetite dominated rock and alteration zone. As a consequence of this geophysics can be used to model, in three dimensions, the distribution of the host rock, and by interpretation guide drilling towards the copper rich zones.
Three-dimensional modelling of the host rock has demonstrated that the target mineralised units extend to depths of greater than 1000m, so nearly twice the depth of mineralisation defined by drilling to date.
A Zone Open Pit Infill
A drill program has been designed that aims to test the areas in the A Zone hangingwall and footwall for additional mineralisation that would be captured within an open-pit, and increase the overall A Zone Mineral Resource estimate. A comprehensive review of historical drilling has shown several areas where chalcopyrite (the mineral containing copper) was identified in historical drilling, but the intervals were not assayed because they were visually assessed to contain less than 2% copper. The historical mine was operating a head grade of approximately 2.3% copper, and so material with a visual grade below 2% copper was not considered to be significant.
Geological modelling suggests that material with a grade above about 0.4% copper would be mined, if it occurs within a planned open pit. This would also reduce the strip ratio.
The company undertook one test of this concept in late 2014 when it drilled VDD 182. This hole intersected a hangingwall zone of 8m at 0.4% copper and a footwall zone returning 10.6m at 0.5% copper. The footwall zone correlated with a historical interval from VRD 068 of 13m at 0.7% copper, located 80m above. This demonstrates that these hangingwall and footwall zones do exist and a targeted drill program within the area of the planned open pit is expected to deliver positive results.
A Zone South Deeps
A drill program has been designed that aims to extend the A Zone Mineral Resource to the southwest along plunge. This area is referred to as the A Zone South Deeps and is adjacent to some of the deepest underground mining development (~650m below surface) that was completed during the operation of the historic Viscaria Copper Mine.
Intersections in this area have included:
- 6.5 metres at 3.4% Cu in VDD 127 (drilled in 2012)
- 4.2m at 2.7% Cu in historical hole D-4682
- 7.2m at 2.7% Cu in historical hole D-8308
- 5.5m at 2.2% Cu in historical hole D-4689
- 4.9m at 2.6% Cu in historical hole D-4689 – the deepest intersection on the Viscaria deposit to date at approximately 840m below surface