West Dome Underground project continues to expand with ongoing drilling revealing a growing opportunity
Wide, high grade results from Western Stockwork Corridor, adjacent to the existing high grade Western Limb and Eastern Limb
Greatland Resources AGM 2025: What You Need to Know
Highlights
§ 19 holes for >9,000 metres completed from the West Dome Underground (WDU) Phase 2 drilling program, with results received from 9 holes. The drilling program has largely focused on growth drilling for H1 FY26, targeting the southern extension of mineralisation.
§ Increasing drill density has improved our understanding of the WDU, with three mineralised domains now confirmed: a broad sub-vertical Western Stockwork Corridor (WSC), flanked by the extensive Western Limb and Eastern Limb high grade shoots hosted within the Lower Limey Unit (LLU), an important geological horizon for gold-copper mineralisation at Telfer.
§ Recent drilling has returned exceptional drilling results in the WSC domain over a broad zone of stockwork mineralisation, with results across a large zone between 40-70m wide (true width) and over 200m down dip extent:
– 56.6m @ 2.24g/t Au & 1.26% Cu (127 gram-metres Au (gm)1) from 337m (WUC4550083)
– 82.2m @ 1.90g/t Au & 0.31% Cu (156gm) from 360.7m (WUC4550092)
– 66.5m @ 1.18g/t Au & 0.16% Cu (78gm) from 334m (WUC4550085)
– 24.0m @ 1.18g/t Au & 0.10% Cu (28gm) from 309m (WUC4550081)
– 22.5m @ 1.43g/t Au & 0.01% Cu (32gm) from 396m (WUC45500992)
§ In addition, high grade mineralisation continues to be intercepted within the LLU across both the Eastern Limb and Western Limb, with mineralisation on both limbs now over 500m in strike and remain open. The following significant results have been received to date:
Western Limb LLU
– 34.5m @ 4.06g/t Au & 0.31% Cu (140gm) from 418.5m (WUC45500992)
– 29m @ 1.86g/t Au & 0.34% Cu (54gm) from 341m (WUC4550081)
– 5.5m @ 3.57g/t Au & 0.29% Cu (20gm) from 389m (WUC4550083)
– 6.84m @ 2.28g/t Au & 0.25% Cu (17gm) from 440m (WUC4550092)
– 7.15m @ 2.32g/t Au & 0.13% Cu (15gm) from 416m (WUC4550085)
Eastern Limb LLU
– 35m @ 2.9g/t Au & 0.19% Cu (101gm) from 234m (WUC45500992)
– 30m @ 5.6g/t Au & 0.25% Cu (168gm) from 281m (WUC45500992)
– 26.6m @ 2.7g/t Au & 0.30% Cu (71gm) from 302m (WUC45501112)
– 6.7m @ 1.88g/t & 0.39% Cu (12gm) from 154m (WUC4550083)
– 3.85m @ 4.1g/t Au & 0.38% Cu (16gm) from 168m (WUC4550092)
§ Development and study work:
– Existing Telfer infrastructure supports the potential to accelerate a new mine at WDU, with the ability to utilise the existing Main Dome Underground (MDU) infrastructure that previously supported an underground mining rate in excess of 5Mtpa (Main Dome Underground mining rate currently approximately 1.2Mtpa).
– A pre-feasibility study is underway and will assess utilisation of the existing MDU infrastructure, including the existing ventilation system, underground haulage shaft and crusher system.
– Second development drive is approximately 60% of the distance to the current drilling location. Once complete, the second drive will provide significant optionality to further increase drilling activities and advance any early works.
§ A third diamond drill has been allocated to the West Dome Underground, to accelerate drilling and support delivery of a maiden Mineral Resource Estimate targeted for the March 2026 quarter.
Notes:
(1) Formula: gm = interval width multiplied by Au grade
(2) Result reported in the announcement “September Quarter Resource Development & Exploration Update” on 22 October 2025
Greatland Managing Director, Shaun Day, commented:
“We continue to see excellent drilling results and progress at the compelling West Dome Underground project.
“The Main Dome Underground began production almost 20 years ago and continues operating today, having produced more than 3 million ounces of gold to date. Our West Dome Underground drilling confirms that key geological units and mineralisation styles at the Main Dome Underground are present at the West Dome Underground, and continues to deliver high grades and excellent widths.
“Access to the West Dome Underground effectively opens access to a new quartile of the Telfer mine, being the two open pits and potentially the opportunity to start a second underground mine.
“Drilling to date has now identified three separate mineralised domains, the high grade Western Limb and Eastern Limb, and the wide sub-vertical Western Stockwork Corridor. Mineralisation remains open along strike and down dip. Given the impressive results to date, a third diamond drilling rig has been allocated to the West Dome Underground, which will further inform a targeted maiden Mineral Resource estimate in the March 2026 quarter.
“The second development drive to the West Dome Underground is well progressed, and a pre-feasibility study is now underway and will assess how the substantial existing infrastructure capacity at the Main Dome Underground can be leveraged to deliver a pathway to production.“
Overview
Greatland Resources Limited (Greatland) is pleased to provide this update on the West Dome Underground project.
The FY26 WDU drilling program aims to continue to expand the mineralisation footprint while at the same time infilling existing drilling to an adequate spacing (40m x 40m) to support Mineral Resource estimation and subsequent mining studies to support a decision to mine.
Drilling has initially focused on the less drilled southern extent of the mineralised system, with results to date indicating an increase in grade and thickness within the Eastern Limb and sub-vertical WSC, while continuing to confirm the high-grade mineralisation seen within the Western Limb during previous drilling programs.
Drilling will progress northwards over the remainder of FY26, with a further 22,500m of drilling planned to continue to infill existing drilling along with testing vertical extent of the system (above and below the LLU).
The maiden Mineral Resource estimate is targeted in the March 2026 quarter. In the meantime, based on the impressive results to date a number of workstreams are underway to progress the potential development of the WDU as an additional high grade ore source.
Figure 1: Telfer Deposit mine area Location Map
Drilling Results Discussion
Western Stockwork Corridor
The WSC mineralisation is located within the hinge of the WDU fold (Figure 2) and consists of a broad zone of concordant and discordant stockwork/sheeted and breccia veins, containing chalcopyrite, pyrite, white & pink dolomite, quartz and galena. There is also a notable overprinting of albite alteration.
The potential of this domain was first identified during the maiden underground drilling campaign, which although focused on the high-grade Western Limb also intercepted several broad zones of stockwork mineralisation within the hinge of the LLU fold with the following promising results:
§ 42.0m @ 1.97 g/t Au & 0.49% Cu (83gm) from 294.0m (WUC45500193)
§ 18.4m @ 3.93 g/t Au & 0.92% Cu (72gm) from 330.6m (WUC45500203)
§ 36.1m @ 2.14 g/t Au & 0.21% Cu (77gm) from 365.9m (WUC45500233)
§ 31.7m @ 1.34 g/t Au & 0.35% Cu (42gm) from 366.0m (WUC45500223)
§ 23.3m @ 1.64 g/t Au & 0.54% Cu (38gm) from 341.0m (WUC45500303)
Recent drilling to the south (Figure 2) has continued to return multiple intercepts of broad higher-grade mineralisation within the WSC, with the following significant results received:
§ 56.6m @ 2.24g/t Au & 1.26% Cu (127gm) from 337m (WUC4550083)
§ 82.2 @ 1.90g/t Au & 0.31% Cu (156gm) from 360.7m (WUC4550092)
§ 66.5m @ 1.18g/t Au & 0.16% Cu (78gm) from 334m (WUC4550085)
§ 24.0m @ 1.18g/t Au & 0.10% Cu (28gm) from 309m (WUC4550081)
§ 22.5m @ 1.43gt Au & 0.01% Cu (32gm) from 396m (WUC45500992)
The drilling to date confirms continuous WSC mineralisation over 700m of strike, averaging approximately 40m wide (true width) x 150m dip extent (height), and remains open along strike, and up and down dip. These recent results indicate higher grade and increased width to the south of the Phase 1 drilling.
The WSC is considered comparable to the Vertical Stockwork Corridor or ‘VSC’ domain that was one of the dominant domains targeted by the Sub-Level Cave (SLC) at the Telfer Main Dome Underground from 2008 to 2019 (mining approximately 5Mtpa on average) and is a key extension opportunity currently under assessment.
Note (3): Result reported in the Greatland Gold plc AIM announcement “West Dome Underground Project” on 20 February 2025
Western Limb
The Western Limb of LLU mineralisation has returned some of the highest grade WDU results to date, and continues to do so. Mineralisation has been confirmed over 700m in strike, averaging 10m wide and over 100m down dip to date, and remains open to the north and south.
The following recent significant results have been returned:
§34.5m @ 4.06g/t Au & 0.31% Cu (140gm) from 418.5m (WUC45500992)
§ 29m @ 1.86g/t Au & 0.34% Cu (54gm) from 366m (WUC4550081)
§ 5.5m @ 3.57g/t Au & 0.29% Cu (20gm) from 389m (WUC4550083)
§ 7.15m @ 2.32g/t Au & 0.13% Cu (17gm) from 416m (WUC4550085)
§ 6.84m @ 2.28g/t Au & 0.25% Cu (16gm) from 447m (WUC4550092)
Eastern Limb
The Eastern Limb mineralisation is hosted with the same LLU unit that has hosted the Western Limb and has been defined over 500m in strike, 100m dip extents and averaging 10m true width (Figure 2).
As reported in the announcement “September Quarter Resource Development & Exploration Update” on 22 October 2025, recent drilling results have returned higher grade mineralisation in this Eastern Limb as we have drilled to the south, with recent results returning similar grades to those seen in the Western Limb.
The following recent significant results have been returned:
§ 35m @ 2.9g/t Au & 0.19% Cu (101gm) from 234m (WUC45500991)
§ 30m @ 5.6g/t Au & 0.25% Cu (168gm) from 281m (WUC45500991)
§ 26.6m @ 2.7g/t Au & 0.30% Cu (71gm) from 302m (WUC45501111)
§ 6.6m @ 1.88g/t Au & 0.39% Cu (12gm) from 154m (WUC4550083)
§ 3.85m @ 4.1g/t Au & 0.38% Cu (16gm) from 168m (WUC4550092)
§ 4.75m @ 1.68g/t Au & 0.13% Cu (8gm) from 155m (WUC4550081)
§ 12.6m @ 1.39g/t Au & 0.13% Cu (17.5gm) from 209.4m (WUC4550102)
Figure 2: West Dome Underground “3D Isometric view” looking north
Figure 3: West Dome Underground Geological Type Section
Main Dome Underground infrastructure
The MDU is situated below the Main Dome Open Pit, and to date has mined over 75Mt of ore, for more than 3.1Moz gold and 210kt copper.
In 2007, construction of a 6Mtpa capacity underground crusher, dual conveyor, shaft and hoist was completed and has been in continuous use since then. The MDU mainly operated as a sub level cave from 2008 to 2019, extracting on average 5Mtpa, before the mine moved to long hole open stoping.
Currently the Main Dome Underground is operating at a mining rate of approximately 1.2Mtpa. Accordingly, there is significant available infrastructure capacity at the MDU to support potential mining operations at WDU, including:
§ 6Mtpa crushing and haulage capacity via the existing shaft. The crusher is located at a depth of approximately 1,000m and would be accessible from WDU by development of a ~1.5km lateral haulage drive;
§ Water pumping infrastructure with installed capacity of 132L/s, with current mining activities in the MDU utilising on average 50L/s;
§ Ventilation infrastructure designed for ~5Mtpa SLC, currently operating as a ~1.2Mtpa stoping operations;
§ Electricity generation from the Telfer power plant and transmission via the MDU; and
§ Paste plant.
Figure 4: MDU shaft headframe (left), underground conveyor system (right)
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Figure 5: MDU water pumping station (left) and paste plant (right foreground)
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Development and study work
The current drilling program is on track to inform a maiden Mineral Resource estimate targeted in the March 2026 quarter and provide input into metallurgical and geotechnical test work.
The second parallel development drive from MDU to WDU has now been developed to a length of approximately 1,100 metres, providing a primary ventilation loop and is approximately 60% of the way to the existing diamond drill location, which sits 200-300m from the WDU mineralisation. This drive will facilitate greater rates of exploration drilling and the option to accelerate early works development.
A pre-feasibility study for WDU is underway, with metallurgical, hydrogeology, and geotechnical testwork program scheduled in H2 FY26. The study will assess the utilisation of the existing MDU infrastructure, along with key infrastructure components such as upgrading the existing paste plant (Figure 5 above), and the tailings supply options for paste backfill. It will also consider processing optimisation with future Havieron ore.
Contact
For further information, please contact:
Greatland Resources Limited
Shaun Day, Managing Director | Rowan Krasnoff, Chief Development Officer
