Red Mountain Mining Expands Oaky Creek South Antimony Target Before July Drilling

Red Mountain Mining Drills Into a Bigger Target: IP Modelling Extends Antimony Strike at Oaky Creek South

Red Mountain Mining Ltd (ASX: RMX) has reported a material geophysical update at the Oaky Creek South prospect within its 100% owned Armidale Antimony-Gold Project in New South Wales. According to the 9 July 2026 ASX announcement, 2D and 3D modelling of dipole-dipole induced polarisation (DDIP) data has defined a coherent chargeability anomaly that now appears to extend the antimony target from a surface strike of approximately 120 metres to at least 400 metres, with a vertical extent of more than 100 metres. Red Mountain Mining Oaky Creek South antimony drilling starts in July 2026, marking a significant step forward for this emerging critical minerals project.

The anomaly strengthens to the south-southwest (SSW) and remains open in that direction. It sits beneath and along strike from outcropping quartz-carbonate-stibnite veins and shallow historical antimony workings at Oaky Creek South.

This upgraded geophysical target will be tested as part of Red Mountain Mining Ltd's maiden reverse circulation (RC) drilling program at Oaky Creek, contracted to commence the week beginning 20 July 2026 with Durock Drilling. Up to 32 RC drillholes are planned, to a maximum depth of 300 metres, across four of five priority orogenic antimony-gold targets within a ~3 kilometre surface system.

What the DDIP Geophysics Is Indicating at Oaky Creek South

According to the ASX announcement, the orientation DDIP survey at Oaky Creek South was completed by Fender Geophysics over four lines for a total of 6.3 line kilometres. Three lines were oriented northwest-southeast (NW-SE) at 100 metre spacing, each 1.6 kilometres long, with a fourth line oriented southwest-northeast (SW-NE) to intersect key structures, including a splay of the Namoi Fault.

The survey was designed to:

• Test the subsurface electrical response across the Oaky Creek South Main Grid (OCSMG) antimony-arsenic auger soil anomaly
• Extend across surface quartz-carbonate-stibnite vein mineralisation and shallow workings at the Oaky Creek South Workings (OCSW)
• Intersect a major Namoi Fault Splay (NFS), interpreted as a potential feeder structure for orogenic antimony mineralisation

Key DDIP chargeability outcomes reported by Red Mountain Mining Ltd are:

• Peak chargeability: 7.2 mV/V, compared with typical background values of 2–3 mV/V
• Orientation: A coherent NNE-SSW striking, steeply SE-dipping anomaly beneath and SSW of the OCSW veins and workings
• Strike length: Modelled to extend at least 400 metres, compared with the ~120 metre surface footprint of outcropping veins
• Depth extent: Modelled to extend to more than 100 metres below surface
• Open SSW: Strongest development on the southernmost line (Line 10000N), remaining open to the SSW
• Interpretation: Potentially represents chargeable sulphide (stibnite-rich) within steeply dipping quartz-carbonate-stibnite veins similar to those mapped at surface

In addition, a weaker chargeability response was modelled beneath the central part of the OCSMG soil anomaly:

• Peak chargeability: 3.91 mV/V
• Appears near-vertical on one line and shallow to flat-lying on another
• Interpreted as a shallower, less intense response than the main OCSW anomaly

The 3D modelling suggests the main OCSW anomaly extends at least 150 metres beyond the southernmost survey line, which supports a minimum strike length of 400 metres and indicates potential for further extension.

Resistivity values from the DDIP survey ranged from 100 to 1,200 ohm-metres, within the range expected for the metasedimentary host rocks. Red Mountain Mining Ltd notes that subtle resistivity variations similar to these have been used at Larvotto Resources' Hillgrove antimony-gold deposit to track vein-hosted mineralisation and silica-sericite alteration envelopes. However, the company states that in the absence of subsurface drilling at Oaky Creek South, the DDIP resistivity data alone cannot yet be interpreted as direct evidence for, or against, the presence of antimony mineralisation.

Educational Focus: Understanding Induced Polarisation and DDIP

For investors, the technical term induced polarisation (IP) can be a barrier to understanding why a survey result is material. The Oaky Creek South work provides a clear real-world example of how this method is applied in practice.

What Is Induced Polarisation?

Induced polarisation is a geophysical technique used to detect certain types of minerals in the ground, especially metallic sulphides such as stibnite (the main ore mineral for antimony).

• An electrical current is injected into the ground using electrodes.
• When the current is switched off, some minerals temporarily retain electrical charge.
• This delayed release of charge is measured as chargeability, commonly in millivolts per volt (mV/V).
• Higher chargeability values often indicate higher amounts of chargeable minerals, particularly sulphides.

In simple terms, IP measures how strongly the ground behaves like a temporary battery after an electric current is removed.

What Is Dipole-Dipole IP (DDIP)?

DDIP is a specific way of arranging the transmitting and receiving electrodes:

• Electrodes are laid out along straight lines on the surface.
• Pairs of electrodes (dipoles) are used for both transmitting and receiving signals.
• The spacing and configuration are especially effective for detecting narrow, steeply dipping vein systems.

This is particularly relevant at Oaky Creek because the targeted mineralisation is in steep quartz-carbonate-stibnite veins, which are narrow but potentially continuous over hundreds of metres.

Why Do DDIP Results Matter for Investors?

From an investment perspective, DDIP surveys help in two main ways:

1. Target definition before drilling

   • Geophysics can show where zones of elevated chargeability align with known surface mineralisation.
   • This reduces the risk that early drillholes are poorly located relative to the mineral system.

2. Scale and continuity indications

   • Extending a surface anomaly from 120 metres to at least 400 metres in the subsurface suggests that the mineralised system may be more extensive than surface expressions alone indicate.
   • While this does not confirm grade or economic potential, it supports a more confident allocation of drilling metres.

Furthermore, in this announcement, the DDIP data appear to have upgraded the Oaky Creek South Workings target from a localised surface occurrence to a longer, deeper geophysical anomaly that is consistent with the mapped orogenic vein style.

The Oaky Creek Target Package: Five Priorities Across a 3 km System

Oaky Creek is described by Red Mountain Mining Ltd as the most advanced prospect within the 391 km² Armidale Antimony-Gold Project. The project lies within the Southern New England Orogen (SNEO), which is widely regarded as Australia's premier antimony province.

At Oaky Creek, earlier work by Red Mountain Mining Ltd has identified:

• Quartz-carbonate-stibnite veins and breccias hosted in tightly folded and faulted Carboniferous mudstone, siltstone and fine sandstone
• Two clusters of shallow historical pits and shafts at Oaky Creek North and Oaky Creek South
• Coherent soil antimony anomalies extending over a combined ~3 kilometre strike length

Initial soil sampling on a 50 metre x 100 metre grid defined:

• A ~1.5 kilometre, 100–200 metre wide >2 ppm Sb soil anomaly around Oaky Creek North
• A ~1 kilometre >2 ppm Sb soil anomaly extending north from Oaky Creek South

Follow-up rock chip and infill auger sampling has been extensive:

• Approximately 1,300 hand-auger soil samples along the full 3 km strike
• Multiple rock chip samples above 25% Sb and 0.1 g/t Au across five areas
• A peak rock chip assay of 39.3% Sb and 1.09 ppm Au at Oaky Creek

These datasets have allowed Red Mountain Mining Ltd to define five priority orogenic antimony targets at Oaky Creek, four of which are scheduled for drilling in Q3 2026.

Priority Targets and Status

Taken together, these features support the interpretation of a 3 kilometre long orogenic antimony system rather than isolated showings.

Maiden RC Drill Program: Specifications and Timing

Red Mountain Mining Ltd has engaged Durock Drilling to undertake the maiden RC program at Oaky Creek, with a contracted start date of 20 July 2026. The program has been fully approved by the NSW Resources Regulator.

Program Summary

The initial RC holes are planned to be 100–150 metres deep, which Red Mountain Mining Ltd states is designed to confirm continuity of mineralisation from surface. The approved maximum depth of 300 metres will enable follow-up of down-dip extensions if mineralisation is intersected.

The approval does not restrict drill collars to pre-defined points, which allows the company to move holes in response to early intercepts. For investors, this flexibility can be important in early-stage programs where new geological information can rapidly refine the model.

Orogenic antimony systems are reported to possess significant vertical extent. Red Mountain Mining Ltd references Larvotto Resources' Hillgrove deposit, which is documented to extend to depths of more than 1 kilometre, as an example of vertical continuity in this style of mineralisation.

Benchmarking Oaky Creek: the Hillgrove Comparison

The ASX announcement draws a direct geological comparison between Oaky Creek and Larvotto Resources' Hillgrove antimony-gold project, situated to the east of Red Mountain's tenement.

Key comparative points outlined by Red Mountain Mining Ltd include:

• Both projects are located within the Southern New England Orogen
• Both host orogenic quartz-carbonate-stibnite vein mineralisation in Carboniferous metasediments
• Oaky Creek's ~3 kilometre surface strike of antimony anomalism is stated to be analogous in scale to Hillgrove
• Hillgrove is described as Australia's largest known antimony deposit and 8th largest globally
• DDIP resistivity values at Oaky Creek fall within the same range as gradient array IP values reported at Hillgrove

Red Mountain Mining Ltd does not claim equivalence of resources or economics to Hillgrove. Rather, the comparison is used to contextualise the geological setting and potential scale that orogenic antimony systems in the SNEO can reach when well developed and drilled out.

Metallurgical Testwork: Early Processing Indicators

Beyond exploration, Red Mountain Mining Ltd has also completed initial metallurgical testwork on material from Oaky Creek. As referenced in the ASX announcement, a 20 kg bulk sample of stibnite vein material was subject to crush, grind and flotation testing.

The reported outcomes were:

• Concentrate grade of 51.8% Sb
• 85% antimony recovery

These figures suggest the antimony-bearing material responds positively to conventional flotation processing. While early-stage and based on a limited sample, such results are often viewed by investors as a useful early indicator that the metallurgy is not unusually complex.

Project-Level Context: Armidale Antimony-Gold Project

The Armidale Antimony-Gold Project, held 100% by Red Mountain Mining Ltd under EL9732, covers 391 km² along approximately 85 kilometres of strike on the western side of the Peel Fault in the SNEO.

Key geological context from the ASX announcement includes:

• Dominance of isoclinally folded Carboniferous metasediments of the Tamworth Belt
• Association with ultramafic mélanges of the Great Serpentinite Belt along the Peel Fault
• The Peel Fault System hosts over 400 known orogenic gold and base metal occurrences along more than 400 kilometres of strike, but has been subject to fewer than 200 mostly shallow drillholes

Within this broader setting, Oaky Creek is described as the company's highest-priority and most advanced prospect, with additional gold and antimony occurrences such as East Hills, Horsley Station, and Horsley North also present on the tenure.

Key Developments for Investors to Watch

According to Red Mountain Mining Ltd, several near-term milestones are now in focus at Oaky Creek. Consequently, with Red Mountain Mining Oaky Creek South antimony drilling starts in July 2026, each of the following developments carries material significance for the market:

1. Commencement of RC drilling (week of 20 July 2026)

   • Confirmation that physical drilling is underway at OCSW, OCSMG and the northern targets.

2. Initial geological observations from early holes

   • While assays are needed for grade, early logging may indicate whether quartz-carbonate-stibnite veins continue at depth along the DDIP anomalies.

3. Assay results during Q3 2026

   • The company anticipates all RC assay results will be received within the current quarter, providing the first quantitative test of the Oaky Creek antimony-gold system below surface.

4. Potential refinement of drill targeting

   • The approved drilling plan allows collar positions to be adjusted in response to early results, including testing for strike and depth extensions if mineralisation is intersected.

5. Further geophysical interpretation

   • Modelling of the gradient array IP dataset collected alongside DDIP is still in progress and may add further detail to the

Ready to Follow Red Mountain Mining's Maiden Drill Programme at Oaky Creek?

With RC drilling contracted to commence the week of 20 July 2026 and assay results expected within Q3 2026, Red Mountain Mining Ltd (ASX: RMX) is approaching a critical inflection point for its Armidale Antimony-Gold Project. To stay across drill results, project updates, and company announcements as they happen, visit the Red Mountain Mining investor hub and register your interest today.