An updated mineral resource estimate at the Bombora gold deposit within the Lake Roe gold project owned by Perth junior Breaker Resources (ASX: BRB) has confirmed it to be a significant greenfields discovery for Western Australia’s goldfields region.
The update – totalling 24.6 million tonnes at 1.4 grams per tonne gold for 1,084,000 ounces – represents a 107% increase in tonnage and a 74% increase in contained ounces for the project, compared to the maiden resource previously announced in April.
It includes a high-grade core of 808,000oz at 2.0g/t gold (12.5mt) reported above 1.0g/t gold, or 417,000oz at 3.4g/t gold (3.9mt) reported above 2.0g/t gold, and remains open in all directions.
The updated resource has been driven by the results of a 25,500 metre extensional and in-fill drilling campaign completed since the April announcement, and an improved geological model created from an increased understanding of the mineralisation controls.
Breaker said the new model provides it with “more confidence in delineating high-grade internal domains and interpreting continuous mineralisation within the quartz dolerite host unit”.
New exploration target
A revised exploration target of up to to 1.4 million ounces of gold, estimated over a vertical distance of 450m below the updated mineral resource has also been confirmed.
The target is based on proposed diamond drilling which has commenced but will likely take several years to implement, transitioning from initial scoping-style drilling to full drill-out, subject to ongoing success.
Breaker executive chairman Tom Sanders said the updated resource and exploration target signals a “pivotal moment” for Bombora.
“We have achieved our previous exploration target of over 1moz just five months after announcing it and we have mapped out a clear pathway to materialise the value of this exciting discovery,” he said.
“With a much clearer picture of the mineralisation controls to hand, we are now finding a lot more gold, more quickly and this is reflected in an improved discovery cost of $18/oz compared to $23/oz for our maiden resource.
Avenues for growth
Mr Sanders said Breaker has “multiple avenues” to continue growing the Bombora resource along strike, at depth and regionally with a planned aggressive drilling program using up to four rigs.
The most immediate opportunity exists at depths below 250m, where the presence of continuous high-grade gold mineralisation in steep and flat orientations provides an “obvious focus” for drilling.
Priorities include delineating and upgrading more shallow ounces, conducting deeper drilling to scope out underground potential, and testing a large number of targets surrounding Bombora.
In parallel with the drilling, Breaker has begun a pre-feasibility study at Bombora to assess the viability of a standalone open pit mining operation, with future underground potential.
Early open pit optimisation studies completed at a gold price of A$1650 per ounce have indicated “reasonable prospects for eventual economic extraction”.
“With no mining legacy issues at Bombora and a [substantial] gold endowment within the top 150m of the deposit, there is compelling open pit potential which will be evaluated by our study over the coming months,” Mr Sanders said.
Gold deposits in the Lake Roe region typically occur as sulphide-impregnated “lode” and stockwork mineralisations in the upper, iron-rich part of the thick Bombora dolerite.
This style of mineralisation dominates WA’s goldfields and is similar to that found at several major gold deposits in the area including Golden Mile, St Ives, Paddington and White Foil.
The 2.2 kilometre Bombora discovery forms part of an 8km-long greenfields gold system concealed by thin transported cover, typically up to 10m, within Lake Roe.
Metallurgical test work conducted by Breaker earlier this year indicated gold recoveries at Bombora in the range of 99% in oxide, and fresh mineralisation and gravity gold of between 31% to 90%.
At mid-afternoon, shares in Breaker Resources were trading 24.44% higher at $0.280.