Cobre Ltd (ASX:CBE) has discovered multiple quartz units and defined a high-purity quartz exploration target at its wholly-owned Perrinvale Project in Western Australia.
In late 2023 mapping work on the project identified saccharoidal quartzite within the Mt Alfred area on the east side of the project. Lacking any visible accessory minerals or lithic particles, Cobre considered the potential for the project to host high-purity quartz.
After completing desktop work and two programs of fieldwork with analytical testing, Cobre identified extensive, often pegmatitic, quartz units across the southern Panhandle area on the west side of the project, culminating in the maiden exploration target.
Perrinvale exploration target
Notably, all silica assays fall within the feedstock grades for silicon smelting, with 94% of assays between 99.15% and 99.66% silica (SiO2).
The exploration target is 5.1 million tonnes to 28.3 million tonnes at a pre-beneficiation SiO2 grade of 99.1% to 99.6%. The volume and tonnage are based on field observations, including the identification of outcrop margins and strike extents, which were used to calculate surface areas of the observed quartz units.
Cobre CEO Adam Wooldridge said: “The company has long seen copper as a key exposure to growth stimulated by the drive to net zero and the associated electrification.
“Silicon is now recognised as another critical metal and this work by the team is demonstrating the Perrinvale Project has the potential to host very large resources.
“While our interests in Botswana have been and will remain front and centre of the company’s exploration activities, we are excited to continue our exploration efforts at Perrinvale and work to deliver a critical mineral resource.
“Establishing the potential to move the quartz exploration target from a valuable bulk product to an ultra-high purity product can be achieved with a relatively low-cost follow-on work program with considerable value add.”
Conversion to mineral resource
A combination of beneficiation testing and further field data collection is needed to convert the exploration target to a mineral resource.
There are two separate refinement pathways that high-purity quartz can take — a process flow of beneficiation that progressively strips contaminants, and via submerged arc furnace to produce silicon metal.
The work will include bench scale beneficiation testing, deportment analysis, thermal stability assessment and additional fieldwork.
Example of the pegmatitic texture developed in quartz units present in the Southern Panhandle area.
Cobre is now moving to bench-scale beneficiation testing on material retained from earlier sampling programs. This phase will involve sizing analysis, attrition, flotation, magnetic separation and leaching. These tests aim to assess the material's amenability to advanced refining processes.
If successful in removing significant contaminants, the next step involves sending samples to specialised high-purity quartz testing facilities for further complex chemical and thermal treatments to achieve highest purity levels.
Deportment analysis will evaluate the size, mineralogy and distribution of contaminants within the in-situ quartz. This analysis will be pivotal in determining the complexity of processing required to achieve desired purity levels.
Evaluating the thermal stability index of the quartz is crucial for assessing its performance during silicon smelting.
Additional fieldwork based on a geographically staged approach to converting the exploration target to mineral resources is planned.
In anticipation of drilling, Cobre will progress any required heritage surveys and government approvals in the coming months.