Cosmo Metals Defines High-Grade Antimony Mineralisation at Bingara Project

Cosmo Metals Defines Extensive Antimony Mineralisation at Bingara, With Surface Samples up to 10.3% Sb

Cosmo Metals Ltd (ASX: CMO) has reported high-grade surface antimony results from the +8km long Antimony Gully Trend at its 484.1km² Bingara Project in northern New South Wales. Rock chip samples returned up to 10.3% antimony (Sb) at Plunkett & Cassidy East and 5.37% Sb at Plunkett & Cassidy West. Initial mapping has also outlined sub-parallel lines of lode more than 100 metres apart with strike lengths of up to 1.17km, highlighting the scale of the target ahead of drill definition work.

The update matters because it combines high-grade surface expression, limited prior modern exploration, and clear structural scale in a region already known for antimony-gold mineralisation. Cosmo is still at an early exploration stage. However, the announcement suggests the company has identified a target area that may warrant systematic drill testing after further soil geochemistry and mapping.

What the ASX Release Reported at Antimony Gully

In the release, Cosmo said the Antimony Gully Trend was defined following interpretation of a LiDAR survey flown across the full Bingara Project in May 2025. LiDAR is an airborne surveying method that produces highly detailed surface images and elevation data, making it useful for spotting subtle historic workings and geological features that may be hidden by vegetation or farming disturbance.

The company's first-pass field programme focused on clusters of historic antimony workings in two areas:

• Plunkett & Cassidy in the north of the trend
• Evans & Corrigan / McManus in the south-west

The most material results came from Plunkett & Cassidy, where mapping and sampling outlined two mineralised trends interpreted as parallel lines of lode.

The company stated there has been limited to no previous exploration over these target areas. For investors, that increases the relevance of the current results because the system appears to have been identified from surface and historical evidence rather than tested by drilling.

Does Plunkett & Cassidy West Show the Broadest Footprint?

According to the release, Plunkett & Cassidy West contains the most extensive historic antimony pits and workings. Mapping defined a 500m strike of persistent oxidised quartz breccia float and subcrop, with the trend interpreted to continue for a further ~670m, giving a potential total strike of ~1.17km.

At its widest point, brecciated quartz was observed across approximately 90 metres. Cosmo noted this may reflect multiple parallel lodes rather than a single mineralised body, whilst the main mineralised corridor itself was described as being more than 10 metres wide.

The best laboratory assay from this western trend was 5.37% Sb from sample AG25, which the company described as quartz breccia containing visible, metallic stibnite.

Plunkett & Cassidy East Delivered the Highest Grade

At Plunkett & Cassidy East, historic workings are subtler and have likely been affected by recent farming activity. Even so, Cosmo mapped a discontinuous strike length of roughly 220m consisting of mine dump material and quartz subcrop, with isolated anomalous quartz float located a further ~370m north.

That gives a possible strike extent of up to 590m, based on the company's interpretation. Sampling on this eastern trend returned a peak result of 10.3% Sb from sample AG10 in quartz float.

The release also noted consistently elevated arsenic values across the Plunkett & Cassidy area. In exploration, arsenic can act as a pathfinder element, meaning it occurs alongside the target mineral system and helps geologists trace a broader zone of mineralisation.

"The recent on-ground mapping and surface sampling at the +8km long Antimony Gully Trend has highlighted this area's prospectivity for large scale antimony-gold mineralisation, particularly at the Plunkett & Cassidy prospect, with its +1km strike extent and potential for multiple parallel shoots over 100's of metres," said Ian Prentice, Managing Director of Cosmo Metals.

Why the Geological Observations Matter

Beyond the headline assays, the ASX update pointed to several geological features that may be important when ranking future drill targets.

Cosmo reported vuggy and drusy textures in vein and vein breccia material. In simpler terms, these are open cavities and crystal-lined spaces within the rock. Geologists often associate these textures with the upper parts of hydrothermal systems, where mineral-rich fluids moved through fractures and deposited metals.

The company interpreted these textures to mean the current outcrop may represent the upper level of an antimony-gold structure, rather than the core of the system. Furthermore, according to the release, this interpretation is supported by the combined Sb-Au-As-Hg geochemical signature.

That does not confirm higher grades at depth. However, it does help explain why follow-up exploration is being directed toward defining drill targets rather than stopping at surface sampling.

What Is Stibnite and Why Does It Matter?

One of the more important technical details in the release was the confirmation of visible antimony sulphide, or stibnite (Sb₂S₃), in sample AG25 at Plunkett & Cassidy West.

Stibnite is the main ore mineral of antimony. It is typically a metallic grey sulphide mineral that forms in hydrothermal veins, often alongside quartz and sometimes with gold-bearing systems. When explorers identify visible stibnite in hand specimen, it provides more confidence that the antimony is present as a primary mineral rather than only as a weathered surface anomaly.

For non-specialist investors, this distinction matters. Surface geochemistry alone can sometimes reflect dispersed or remobilised metals. By contrast, visible stibnite within quartz breccia indicates that primary mineralisation is present in the rock itself.

Quick Glossary

• Antimony (Sb): A metallic element used in alloys, flame retardants and industrial applications.
• Stibnite: The main antimony sulphide mineral and a key ore source of antimony.
• Quartz breccia: Quartz-rich rock made up of broken angular fragments cemented together, commonly linked to mineralised fault zones.
• Line of lode: A linear mineralised trend, often following a vein or fault structure.
• Pathfinder elements: Associated elements such as arsenic and mercury that help identify a broader mineral system.
• LiDAR: Airborne laser-based mapping used to detect subtle terrain and historic workings.

In this case, visible stibnite, quartz breccia, high antimony grades and pathfinder element enrichment all fit the exploration model Cosmo is testing across the Antimony Gully Trend.

Regional Setting Supports the Exploration Model

The Bingara Project sits in the New England Orogen of northern New South Wales and straddles the regional-scale Peel Fault. In the release, Cosmo described the Antimony Gully Trend as a corridor along the north-east trending Gineroi Fault zone, interpreted as a potential splay off that larger fault system.

This matters because major fault zones often provide the pathways for mineralising fluids. When multiple historic workings align along the same structural corridor, it can suggest that mineralisation is not isolated to one small pit or vein.

The release also noted that Antimony Gully is in the same region as Larvotto Resources' Hillgrove Antimony-Gold Mine. That regional reference provides geological context only. It does not imply that Bingara has the same scale, grade or development status as Hillgrove.

Cosmo further referenced a Geological Survey of New South Wales assessment that identified this broader part of the southern New England Orogen as highly prospective for antimony-gold mineralisation. This supports the regional geological setting rather than providing any project-specific endorsement.

What Comes Next in the Exploration Programme?

The ASX update outlined a staged follow-up programme aimed at converting surface observations into drill-ready targets.

Immediate next steps reported by Cosmo include:

1. Focused soil geochemical sampling
2. Mechanised auger work to sample beneath farming-disturbed surface areas
3. Detailed geological mapping
4. Target identification and prioritisation for subsequent drill testing

This next stage is particularly relevant at Plunkett & Cassidy, where the zone between the eastern and western lodes is largely concealed by shallow cover. If soil sampling detects antimony and pathfinder anomalies between the known trends, it could support Cosmo's interpretation that additional parallel lodes may sit beneath cover.

At Evans & Corrigan, the challenge is different. The release said evidence of historic workings has been obscured by modern farming activity, so auger-assisted soil sampling may be important in determining whether the subtle surface expression reflects a concealed mineralised trend.

Why Investors May Be Watching This Closely

Early-stage exploration results always need to be viewed carefully, particularly where conclusions are based on selective rock chip sampling rather than drilling. Cosmo's own JORC commentary notes that the surface sampling is selective in nature and may not represent the bulk grade of mineralisation at depth.

Even so, several parts of the update are likely to attract investor attention:

• High-grade surface assays, including 10.3% Sb
• Two parallel mineralised trends more than 100m apart
• Strike lengths up to 1.17km
• Visible stibnite in sampled quartz breccia
• Limited previous exploration across the target area
• A defined workflow from mapping and soils to drill targeting

Taken together, those factors suggest that Antimony Gully could become an important near-term exploration focus within Cosmo's broader New South Wales portfolio.

The company also holds the Nundle gold-antimony and copper project, and states that Bingara and Nundle together cover approximately 743km² in the New England Orogen. Additional assets include the Kanowna Gold Project near Kalgoorlie and the Yamarna Project in the Eastern Goldfields. That wider portfolio gives Cosmo more than one exploration front, although the latest ASX release is clearly centred on Bingara.

The Key Point From the Antimony Gully Update

According to the ASX release, Cosmo has defined an extensive antimony-mineralised corridor at Antimony Gully with encouraging geological scale and surface grades. The strongest evidence so far sits at Plunkett & Cassidy, where two sub-parallel lines of lode, visible stibnite, elevated arsenic and strike continuity together support more detailed follow-up work.

The next catalyst is likely to be the soil geochemistry and mapping programme, which is intended to identify and rank drill targets. For investors, the central question is straightforward: can the surface scale and grade now be converted into subsurface continuity through drilling? The company's next round of exploration results should begin to answer that.

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