Great Boulder Resources Ltd (ASX:GBR) is confident of growing the 568,000-ounce Mulga Bill gold resource within the Side Well Gold Project in WA after expanding the mineralisation zone at the Muiga Bill North prospect to 400 metres in strike length.
The company leveraged results from a 13-hole aircore drilling program to confirm the results, which also demonstrate the mineralisation at Mulga Bill North is shallow, beginning just 40 metres below surface, and likely amenable to open pit mining.
A highlight intersection from the drilling was 17 metres at 1.39 g/t gold from 49 metres with a high-grade section of 3 metres at 3.39 g/t from 61 metres, among several results of similar grade.
In addition to exploration at Mulga Bill North, regional aircore drilling along strike from the Saltbush prospect also struck mineralisation in a similar setting to the Ironbark deposit, hitting 1 metre at 0.41 g/t gold from 76 metres in drill hole 24SWAC273.
Two important breakthroughs
“This aircore program at Mulga Bill North covers an area between 1 kilometre and 1.4 kilometres north of Mulga Bill,” Great Boulder managing director Andrew Paterson said.
“Previously, we had some positive results from a small drill pattern in this area, which highlighted that regional fence lines of drilling completed in 2020-21 were ineffective at testing the area’s potential.
“The new results provide two important breakthroughs. Firstly, we’ve hit zones of shallow gold mineralisation 40 metres below surface, supporting our view that Mulga Bill North can make an important contribution to the Side Well resource inventory with real potential for large-scale open pit mining.
“Secondly these new intersections fit our previous interpretation, with multiple lodes similar to Mulga Bill and good strike continuity.
“We have mineralisation over a 400-metre extent along strike, with only a small amount of additional drilling required to bring this area into resource.
“There are still five holes remaining in the program which we couldn’t complete at the time due to wet weather.
“The rig will head back there shortly to finish these holes but meanwhile we’re busy drilling reverse circulation (RC) holes to extend the northern end of Mulga Bill.”
GBR is targeting a mineral resource update for the Mulga Bill prospect in the second half of this year, once all RC and diamond drilling is complete.
New gold target near Saltbush
“In other news we have also identified gold mineralisation beneath a surface geochemical bullseye northwest of Saltbush.
“The gold is coincident with strongly elevated arsenic near a mafic-ultramafic contact, so it fits the Ironbark and Saltbush mineralisation style.
“We intend to head back there and complete more drilling shortly.”
The intersection in hole 24SWAC273 is associated with strongly elevated arsenic adjacent to a mafic-ultramafic contact, the same setting as Ironbark and Saltbush.
Assay results and next steps
Highlight assays from the latest drilling at Mulga Bill include:
- 17 metres at 1.39 g/t gold from 49 metres, including 3 metres at 3.39 g/t from 61 metres;
- 14 metres at 1.77 g/t from 70 metres, including 1 metre at 4.80 g/t from 70 metres and 5 metres at 2.96 g/t from 75 metres;
- 13 metres at 1.98 g/t from 136 metres, including 5 metres at 3.26 g/t from 144 metres; and
- 5 metres at 2.98 g/t from 139 metres and 1 metre at 1.33 g/t from 140 metres to the end of hole.
Great Boulder is still drilling with the RC and diamond rigs at Mulga Bill, targeting further resource definition and deeper extensions of high-grade veins up to 500 metres below the surface.
Once the RC program is finished, the company will move that rig to resource upgrade activities, with the goal of upgrading the resource at Mulga Bill from inferred to the higher confidence indicated JORC category.
Beginning in September, the program will also collect samples from the prospect for metallurgical test work.