The Ironbark deposit sits within exploration licence E51/1905 held by Great Boulder Resources (75%) and Zebina Minerals Pty Ltd (“Zebina”) (25%). The Company has made mining lease application M51/911 over the Ironbark deposit area. Upon grant, M51/911 will be held by the Company (75%) and Zebina (25%). Zebina’s interest will be free-carried through to a decision to mine, at which point Zebina may elect to contribute to development and mining costs on a pro-rata basis or dilute their holding.
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Summary:
The 2025 updated Side Well Mineral Resource Estimate update (MRE) includes estimates for the Mulga Bill, Eaglehawk, Flagpole, Ironbark, Saltbush and Golden Bracelet deposits.
The Side Well tenement group covers a portion of the Meekatharra-Wydgee Greenstone Belt north of Meekatharra, WA. The north-northeasterly-trending Archaean Meekatharra-Wydgee Greenstone Belt, comprises a succession of metamorphosed mafic to ultramafic and felsic and sedimentary rocks belonging to the Luke Creek and Mount Farmer Groups.
Over the northern extensions of the belt, sediments belonging to the Proterozoic Yerrida Basin unconformably overlie Archaean granite-greenstone terrain. Structurally, the belt takes the form of a syncline known as the Polelle syncline. Younger Archaean granitoids have intrusive contacts with the greenstone succession and have intersected several zones particularly in the Side Well area.
Within the Side Well tenement group, a largely concealed portion of the north-north-easterly trending Greenstone Belt is defined, on the basis of drilling and airborne magnetic data, to underlie the area. The greenstone succession is interpreted to be tightly folded into a south plunging syncline and is cut by easterly trending Proterozoic dolerite dykes.
There is little to no rock exposure at the Side Well prospect. This area is covered by alluvium and lacustrine clays, commonly up to 60 metres thick. Subcrop exposures of laterite, mafic and ultramafic rocks are present along the eastern side of the project, however exposure of outcrop is still relatively poor.
Ironbark
The local geology is dominated by the regional Polelle syncline. This syncline is comprised of a lower mafic-ultramafic and Banded iron formation (BIF) sequence folded around a north-north-easterly axis. This stratigraphy includes the Ironbark deposit. These magnetic units have traditionally been the main targets for gold exploration in the Meekatharra area. The core of the syncline is dominated by packages of felsic and intermediate volcanics and volcaniclastics.
The Ironbark deposit lies on the eastern limb of the Polelle syncline, approximately in the same stratigraphic location as the Paddy’s Flat gold camp. It is hosted in the mafic-ultramafic sequence that dips at approximately 75 degrees to the west. An ultramafic schist of 5 - 15m width is flanked by two basalt units creating a 20 - 40m wide host package for structural deformation accompanied by mineralising fluids. It has been interpreted that a thrust fault related dilatational zone has formed at Ironbark due to regional compression that formed the Polelle syncline. Both mafic and ultramafic are intensely altered and veined to a quartz-albite-chlorite-talc-iron carbonate ± fuchsite - sulphide assemblage. Deformation in the form of strong foliation is prevalent through host rock units approximately 50 - 100m outside of the main shear corridor.
Four main west-dipping lodes at Ironbark are related to quartz veining and increased pyrite and are located along contacts of the mafic and ultramafic host units but also step across contacts in places. These west-dipping lodes are interpreted to be consistent through the regolith profile with a small supergene zone developed 10 - 20m below surface. The weathered representations of the primary lodes are thought to come near to or to the surface in several areas. Ironbark’s regolith profile consists of 1 - 4m of proximal colluvium that carries gold anomalism overlying a 20 - 70m thick saprolite layer. Weathering is strongly controlled by the mineralised zone with fresh rock intersected between 40 - 100m below surface.
Mulga Bill and Eaglehawk
Mulga Bill – Eaglehawk gold system has potential to host a large-scale, multi-kilometre gold endowment.
Mulga Bill and Eaglehawk are located approximately 10km east of the township of Meekatharra. The two deposits make up a semi-continuous north-south zone of mineralisation with a combined strike length of approximately 3km. The lithologies, alteration and mineralisation styles are very similar and there is potential for the two deposits to join up with further drilling.
Mineralised lodes can be grouped broadly into three main categories: steep-dipping shear structures, flat to shallow dipping vein sets and supergene related mineralisation. The lodes follow and crosscut a 50m wide zone of dacitic to rhyolitic volcaniclastics and shallow intrusives, with preferential development of structures at lithological contacts. Mineralisation remains open down dip and to the north and south of the current model.
The continuity of mineralisation from Mulga Bill north into Eaglehawk.The resource envelopes span approximately 800m of strike, however the overall Eaglehawk prospect has been defined by drilling over approximately 1.5km of strike, with more than 700m of poorly tested strike extent to the north of current RC drill coverage.
The depth of weathering (depth to the top of fresh rock) is deeper at Eaglehawk than at Mulga Bill, requiring deeper RC holes to define primary gold mineralisation. The more mature Mulga Bill area now hosts a mineral resource of 640,000oz Au within a strike extent of 1.6km. Eaglehawk has the same geological setting and the same mineralisation and alteration styles over a strike of approximately 1.5km
Flagpole
Flagpole sits within the same stratigraphic corridor as Mulga Bill and Eaglehawk on the southern end of the 6km Central Corridor of intrusive-related pathfinder geochemistry. Only two lode styles have been defined at Flagpole: subvertical, shear-hosted mineralisation; and sub-horizontal supergene mineralisation. There is high potential that further drilling in the area will intersect higher-grade vein-hosted gold mineralisation similar to those at Mulga Bill and Eaglehawk.
Saltbush
Saltbush is a geological analogue to Ironbark, with gold mineralisation focused on mafic contacts surrounded by ultramafic country rock. The mafic “keel” which hosts the majority of the gold at Saltbush dips steeply to the west and plunges toward the north-northwest. The majority of resource definition drilling at Saltbush had been completed by late 2024, defining shallow gold mineralisation over approximately 380m of strike.
Golden Bracelet
Golden Bracelet was the first geochemical anomaly to be drill tested within the Side Well South area, with AC drilling quickly identifying shallow gold mineralisation in three sub-parallel target zones northeast and north of the historic Golden Bracelet mine workings. The area forms part of the Eastern Corridor of targets, with mineralisation in a similar setting to that seen at Ironbark and Saltbush.
Subsequent rounds of follow-up AC and RC drilling prioritised exploration of the two eastern-most zones, and these have been defined over 400 to 500m of strike, with broad thicknesses of low to moderate-grade mineralisation dipping steeply to the west.
Dimensions
The Mulga Bill deposit extends approximately 1.6km from north to south, 450 m east to west and is currently known to a depth of ~ 300 m.
The Eaglehawk deposit extends approximately 1.5km of which approximately 800m is within the current MRE and is currently known to a depth of ~ 200m.
The Ironbark deposit extends approximately 770 m from north to south, 130 m east to west and is currently known to a depth of ~150 m.
The Flagpole deposit extends approximately 450m from north to south over a width of approximately 100m east-west, and is known to a depth of approximately 150m.
Saltbush extends approximately 380m from the northwest to southeast over a width of 70m southwest to northeast, and is known to a depth of ~150m.
Golden Bracelet extends approximately 500m from north to south over a combined area of 270m east to west, and is known to a depth of ~150m.
Summary:
The 2025 Scoping Study assumes off-site processing at one of the nearby mills in the area, however at this stage the Great Boulder Resources Ltd. (GBR) does not have a commercial processing agreement in place.
Great Boulder Resources Ltd. (GBR) intends to discuss potential processing agreements with operating mills in the area, including Westgold’s 1.8Mtpa Bluebird plant and Meeka Metals’ 600ktpa Andy Well plant. The Company also has a Memorandum of Understanding (MoU) with Monument Mining Ltd. which may provide access to the Burnakura plant, south of Meekatharra. Monument are working on a scoping study considering restarting the Burnakura plant, with an option to upgrade processing capacity to 750,000tpa. The results of the Ironbark Scoping Study will be shared with Monument as part of the MoU.
The Scoping Study assumes gold recoveries of 95% for oxide and transitional material, and 92% for fresh material in a CIL plant. This is based upon limited initial gravit ........ 