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RED MOUNTAIN MINING LIMITED
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Red Mountain Mining Limited (RMXFF) Strong Assays Extend High-Grade Antimony Mineralisation

2026-03-11 17:55 ET - News Release

Perth, Australia, Mar 12, 2026 - (ABN Newswire) - Red Mountain Mining Limited (ASX:RMX) (OTCMKTS:RMXFF), a Critical Minerals exploration and development company with an established portfolio in Tier-1 Mining Districts in the United States and Australia, is pleased to announce that it has received continued strong assay results from the second tranche of assays for its auger soil sampling program at the Oaky Creek prospect at the Company's 100% owned Armidale Antimony-Gold project in New South Wales.

HIGHLIGHTS:

- Red Mountain has confirmed the presence of multiple drill-ready Antimony targets at the Oaky Creek Prospect following the second batch of analytical results from its comprehensive auger soil sampling program at the Armidale Antimony-Gold Project

- Newly discovered stibnite vein rock samples return up to an exceptionally high grade of 28.1% Sb. The new samples collected ~600m NNW of the Oaky Creek South workings, highlight the potential for a new extension to the current mineralised system at Oaky Creek

- Conventional and auger soil sampling and rock analytical results of up to 39.3% Sb and 1.09ppm Au for Oaky Creek indicate the potential of a large-scale orogenic Antimony-gold vein system with a strike extent of ~3km at surface, which is analogous to Larvotto Resources' Hillgrove project, Australia's largest known Antimony deposit

- Previously identified 200m x 30m Antimony-arsenic anomaly near the Oaky Creek South Main Grid has been extended by a further 30% and remains open to the northeast, with values of up to 251ppm Sb and 1,443ppm As returned

- Soil sampling from southern end of Oaky Creek North has further supported the NNW trending Antimony anomaly, with values of up to 137ppm Sb and 334ppm As. Aligning with previously identified conventional soil anomaly and mineralised stibnite-bearing rock sampling, providing further evidence for widespread antimony mineralisation at Oaky Creek

- Further assays pending for Thompson Falls Antimony Project in the US following recently announced initial high-grade Antimony results

Assay results from the January-February field program across Oaky Creek North and Oaky Creek South have reported numerous highly anomalous samples including a stibnite vein sample collected ~600m NNW of the Oaky Creek South workings returning 28.1% Sb. 42 rock samples now exceed 0.5% Sb at Oaky Creek, further supporting the presence of widespread antimony mineralisation across the Oaky Creek Prospect and potentially indicating an extension to the Oaky Creek South mineralised system.

Results for approximately 900 further auger soil samples collected during January and February remain pending, with assays expected before the end of March. These results will significantly expand coverage at both Oaky Creek North and Oaky Creek South (Figure 1*) and will be used in conjunction with datasets for additional expected orogenic antimony vein targets ahead of planned drill testing in Q2 2026.

New Auger Assay Results Extend Antimony-Arsenic Anomaly at Oaky Creek South As was reported in November 2025, initial auger sampling at the Oaky South Main Grid, located approximately 400m north-northwest of the small historical pits and shafts at Oaky Creek South, defined a coherent NE-striking ~200m x 30m Sb-As anomaly that remained open to the northeast.

Newly received results from sampling completed in late 2025 returned values of up to 251ppm Sb and 1,443ppm As (Appendix 1*) and extend this anomaly ~60m further to the northeast (Figure 2*).

The anomaly remains open in that direction, with analytical results for sampling completed in January and February 2026 pending and represents a priority target for planned drill testing in Q2 2026.

The new results comprise approximately 180 auger soil samples collected over conventional soil anomalies at Oaky Creek South and Oaky Creek North, expanding coverage from the initial ~250 auger samples collected at Oaky Creek South in November 2025 (Figure 1*).

Initial Auger results from Oaky Creek North Confirm prospectivity

The new auger soil results also include initial assays from the southern end of the Oaky Creek North conventional soil anomaly. These samples returned multiple anomalous values of up to 137ppm Sb and 334ppm As (Appendix 1*), defining a coherent NNW-trending antimony auger soil anomaly that correlates with the previously reported conventional soil anomaly (Figure 3*) and the distribution of mineralised stibnite-bearing rock chip samples (Figure 1*).

Pending results from additional auger sampling completed in January and February will allow Red Mountain to refine drill targets at Oaky Creek North ahead of planned drilling in Q2 2026.

New rock assays indicate potential for extensions to mineralisation at Oaky Creek South

Results have also been received for 21 rock chip samples collected during Red Mountain's January-February field campaign at Oaky Creek. Samples were analysed at Intertek's Townsville laboratory for Sb, Ag, As and W using sodium peroxide fusion and ICP-MS finish, and for Au using a 50g fire assay charge and ICP-OES finish. Sample locations and analytical results are listed in Appendix 2*.

As can be seen in Appendix 2*, two samples from the most recent assays returned strongly anomalous antimony results and were both collected from the Oaky Creek South area (Figure 4*).

Sample AAR283 is a quartz-carbonate-stibnite vein sample collected ~150m north of the nearest known outcropping antimony mineralization at Oaky Creek South. The sample returned 28.1% Sb, which is comparable to other high-grade samples from the area. This high-grade result indicates that antimony vein mineralisation extends further north than previously recognised at Oaky Creek South. The area surrounding this sample has been auger sampled (refer to Figure 1* (C) and Figure 2*), with assay results expected later in the month. These results will support the continued development of drill targets by determining the potential for significant antimony mineralisation being associated with outcropping stibnite vein occurrences.

Sample AAR286 is an outcropping sample of quartz-veined, limonitic carbonate breccia that was collected from the wall of a shallow pit located ~230m northeast of the main cluster of historical workings at Oaky Creek South (Figure 4*), approximately along strike of the quartz carbonate sulfide veins that host antimony mineralisation within the workings. The sample contains 0.4% Sb, which indicates that it may represent an extension of the mineralisation 230m to the southwest. Further mapping will be undertaken to confirm this.

Red Mountain's geochemical sampling has defined a significant 3km long orogenic SbAu system at Oaky Creek

The Oaky Creek prospect features quartz-carbonate-stibnite veins and breccias hosted within a tightly folded and faulted sequence of mudstone, siltstone and fine sandstone. The mineralisation has been targeted by two groups of shallow historical pits and shafts at Oaky Creek North and Oaky Creek South.

The Company's initial sampling program at Oaky Creek comprised a 50m x 100m spaced grid soil sampling program centered on a major area of the Namoi Fault, accompanied by rock chip sampling.

As reported, the soil sampling defines a coherent, ~1.5km long, 100-200m wide, NNW-trending greater than 2ppm Sb in soil anomaly extending both north and south of the historical workings at Oaky Creek North and a similarly-oriented ~1km long greater than 2ppm Sb in soil anomaly extending north from the Oaky Creek South workings (Figure 5*).

Sampling campaigns at Oaky Creek4,5 returned multiple samples6,7 with values of over 25% Sb and 0.1g.t Au at five different areas, with mineralised and anomalous rock samples showing a strong spatial correlation to the antimony soil anomaly (Figure 5*). When considered collectively, the soil and rock chip results indicate a significant orogenic antimony mineral system with a strike extent of 3km, which is analogous to Larvotto Resources' (ASX:LRV) (Market Cap. ~AU$720 million) Hillgrove Project, which lies east of Red Mountain's project area.

Final Auger Assay Results Pending Ahead of Priority Drill Targets Definition

Over the past two quarters, Red Mountain has completed a comprehensive ~1300 sample infill auger soil sampling campaign across the full ~3km strike extent of the Oaky Creek prospect (Figure 1*). Following positive results from initial auger sampling at Oaky Creek South, which demonstrated the effectiveness of the technique as a prospect-scale tool for targeting antimony mineralisation, a more comprehensive 50m x 20m and 20m x 20m spaced sampling program was completed to tighten Red Mountain's existing 100m x 50m spaced soil grid in order to better constrain individual high priority drill targets. This detailed systematic work will allow the company to confidently select the most prospective targets within the 3km strike extent system for drill testing, maximising the chances of positive results and delineating the mineralisation at Oaky Creek.

Final analytical results are pending for approximately 900 of the auger samples that were collected in January and February 2026. These results are expected to be received before the end of this month.

Red Mountain anticipates that the results will support the definition of multiple orogenic antimony targets for drill testing at Oaky Creek during the second quarter of 2026.

Red Mountain Armidale Antimony-Gold Project background

RMX's 100%-owned Armidale Antimony-Gold Project covers an extensive claim area across 391km2 in the Southern New England Orogen in northeastern New South Wales. The project is located west of Australia's largest known antimony deposit, Larvotto's (ASX:LRV) Hillgrove deposit, which is also the 8th largest antimony deposit globally.

The SNEO is recognised as Australia's premier antimony province (Figure 6*). Antimony occurs in hydrothermal quartz veins, breccias and stockworks, often with associated gold and/or tungsten mineralisation.

The project has an extensive 85km length along the western side of the Peel Fault. The Peel Fault System has recognised world-class mineral potential, with over 400 known orogenic gold and base metal mineral occurrences along its over 400km strike extent, but is underexplored, with less than 200 mostly shallow drillholes over its length, the majority of which are focused on discrete prospects.

Oaky Creek is the company's highest priority prospect within the project and is one of several known orogenic gold and antimony mineral occurrences within the tenement (Figure 7*). At the Armidale Antimony-Gold Project, there remains significant further potential across the tenure for additional discovery as most of the tenure consists of historically reported mineralisation and is highly conducive for modern exploration.

*To view tables and figures, please visit:
https://abnnewswire.net/lnk/FW77X853

About Red Mountain Mining Limited:

Red Mountain Mining Limited (ASX:RMX) is a mineral exploration and development company. Red Mountain has a portfolio of US, Canada and Australia projects in Critical Minerals and Gold. Red Mountain is advancing its Armidale Antimony-Gold Project in NSW, Utah Antimony Project in the Antimony Mining District of Utah, US, Fry Lake Gold Project and US Lithium projects.

Contact:

 
Mauro Piccini 
Company Secretary