The 100% owned Boorara Gold Project is 10 kilometres east of Kalgoorlie’s Super Pit gold mine located on the eastern edge of the city of Kalgoorlie-Boulder, Western Australia. The Boorara Project contains over 1.5 kilometres of gold mineralisation striking north-west at 330 degrees. The project is divided into three project areas, namely Royal (Southern), Crown Jewel (Central) and Regal (Northern) deposits.
Gold mineralisation is hosted in a series of stacked quartz vein arrays that dip at 40-45° to the northwest. The true thickness of the arrays is up to 50 metres vertical and they are hosted within the quartz dolerite which dips at 73° to the northeast. The mineralised dolerite has a true width of up to 40 metres and within the mineralised Boorara dolerite high grade localised ore shoots consist of vein arrays up to 20 metres in width. The increased width of the mineralised dolerite indicates that this is potentially a larger mineralised system.
The Boorara deposit has a JORC 2012 Mineral Resource Estimate of:
16.45 Mt at 0.96 g/t gold for 507,000 oz of gold at a 0.5 g/t lower cut-off grade.
Grade Control (GC) drilling (closer spaced drilling) allows for the complexity of the Boorara deposit to be resolved. Following GC drilling in 2016, a trial pit was completed in the Royal deposit with ore treated at the FMR Greenfields treatment plant at Coolgardie. A total of 30,000 dry tonnes at a head grade of 1.73 g/t produced 1,525 oz of gold, which reconciled well with the GC model. The trial open pit was excavated to a final depth of 20 metres exposing the orebody allowing the quartz veining could to be measured and understanding improved.
On the back of the success of the trial pit and GC drilling, in late 2019, Horizon conducted 18,000m of GC drilling to demonstrate an increase in metal with closer spaced drilling. A revised GC model was developed as a subset of the broader Boorara Resource to 50m depth which was used for open pit optimisation and design in February 2020. The Boorara Stage 1 Feasibility Study indicates an increase in tonnes and grade with the closer spaced drilling, and involves the mining of three starter pits at Boorara within the Regal and Crown Jewel deposits aiming to mine and process a Mining Reserve of 159kt grading 1.86g/t Au for 8,700 ounces recovered at a 91.5% metallurgical recovery, and generate $2.8m of free cashflow at a A$2,000/oz gold price (or $7.1m in cash at a A$2,500/oz gold price).
The key in bringing Boorara Stage 1 into production is for cash generation in 2020 leveraging off the high Australian gold price environment, and to prove the grade control uplift to apply to the greater Boorara resource, leading to a larger scale development.
Following reconciliation of Stage 1, the Mineral Resource estimate for Boorara shall be revised with the aim to establish a solid resource base load to undertake a Feasibility Study to underpin production for a standalone processing facility at Boorara in line with Horizon’s production growth plans.