Great Boulder Resources Ltd (ASX:GBR) has confirmed gold to 500 metres depth at Mulga Bill prospect within GBR’s flagship Side Well Gold Project near Meekatharra in Western Australia.
Two deep diamond holes at Mulga Bill intersected gold in north-plunging high-grade veins and sub-vertical shear-hosted lodes, as predicted by the company’s mineralisation model.
Higher grades than expected
“We drilled two diamond holes to depths of 594 metres and 578 metres to confirm the depth potential at Mulga Bill,” Great Boulder managing director Andrew Paterson said.
“I’m pleased to say we intersected the west-dipping high-grade veins as well as the sub-vertical shear-hosted lodes, as predicted in our mineralisation model.
“We also saw examples of much higher grades than expected within the sub-vertical lodes, such as 1 metre at 19.3 g/t gold from 519 metres in 24MBRCD013.
“In those intersections we saw thin veins of pyrite-hosted gold which appear to be much higher grade than the surrounding rock mass, carrying a lot of the gold in these areas.”
The two diamond holes were oriented at approximately -65° towards the south, with MBRCD013 drilled to 594.3 metres and 24MBRCD017 to 578.1 metres.
This orientation was designed to intersect north-plunging high-grade veins while keeping each hole within the 50-metre-wide mineralised corridor at Mulga Bill to maximise the amount of information gained.
Hole 24MBRCD013 intersected two west-dipping veins, the first of which was outside the high-grade corridor, before drilling through a cross-cutting fault and into a zone of sub-vertical 'Malvern lode' mineralisation.
The northern hole 24MBRCD017 – drilled north of the dyke – intersected a combination of west-dipping Cervelo-style veins and sub-vertical Malvern mineralisation.
Both holes confirm continuity of mineralisation at Mulga Bill to a depth of at least 500 metres below surface. They also help confirm GBR’s north-plunging vein interpretation, intersecting several vein sets with measured orientations dipping towards the west and corresponding to the projected down-hole positions.
Drilling at Mulga Bill has confirmed high-grade mineralisation over more than 2.5 kilometres of strike. Mulga Bill’s current 568,000-ounce gold mineral resource has been defined within the southern 1.1-kilometre extent of this overall 2.5-kilometre mineral system.
GBR believes Mulga Bill has the potential to be one of the largest gold systems in the Meekatharra goldfield.
What’s ahead?
The aircore rig is drilling a large, highly prospective Ironbark-style geochemical target at Side Well South.
The rig will shortly switch back to RC and complete a brief resource definition program at Saltbush to allow this discovery to be included in the upcoming resource update.
The rig will then drill more resource-defining RC holes at Mulga Bill North before returning to Side Well South to continue the aircore program.
Paterson added, “We plan to follow this up with drilling oriented west to east later in the program, most likely in the first half of 2025.
“Drilling on this orientation has a higher probability of intersecting high-grade zones within the north-south corridor.”
Future resource growth and definition drilling at Mulga Bill will focus on Mulga Bill North – representing a significant +1-kilometre northern strike extension to the existing Mulga Bill resource; and Mulga Bill Deeps – testing extensions, continuity and grade of stacked lodes at depth.