Excelsior Project Rock Chip Sampling Defines Six Priority Targets with Significant Assays

Extensive Regional Sampling Defines Multiple Targets

Mammoth Minerals Limited (ASX:M79) has announced the results of a regional rock chip sampling and mapping program conducted in late 2025 across the Excelsior Project in Nevada, USA. The program identified six high-priority target areas exhibiting high-grade gold and critical minerals, including silver, antimony, copper, and lead. These targets are being advanced towards drill-ready status with further detailed exploration planned.

The Excelsior Project is located within the Walker Lane tectonic zone, a prolific gold-producing region with over 20 million ounces of historic gold production. Mammoth holds an exclusive option to earn an 80% interest in the project from Athena Gold Corporation, which retains a 20% free carried interest until a Definitive Feasibility Study is completed.

Key Target Areas and Assay Highlights

The six priority targets include Blue Dick, Kentucky Trend, Stantz Trend, Buster East, Reliance, and the recently acquired Imperial Gold Project area. Notable rock chip assay results include:

• Blue Dick: Surface samples returned up to 1,219 g/t silver, 1.85% antimony, 0.92% copper, and 0.88 g/t gold, with mineralisation interpreted as both Carbonate Replacement Style and epithermal.
• Kentucky Trend: Samples yielded up to 5,580 g/t silver, over 1% antimony, 2.46 g/t gold, and 1.95% copper along a 1,500m strike length with historical mining activity.
• Stantz Trend: Rock chips showed up to 839 g/t silver, 0.48 g/t gold, 11.1% lead, and 1.28% copper over a 1,300m strike.
• Buster East: Located 1.4 km east of recent drilling on the Buster Trend, samples returned up to 28.7 g/t gold and 159 g/t silver.
• Reliance: Rock chips up to 45.5 g/t gold, 126 g/t silver, and 1.3% copper were recorded near historical workings.

Managing Director Glenn Poole highlighted the significance of the critical minerals identified, particularly antimony, which has strategic defence applications and is a focus of US domestic supply initiatives. The company is prioritising reconnaissance and drill permitting at Blue Dick, Stantz, and Kentucky due to consistent high-grade mineralisation and substantial strike lengths.

Advancing Exploration and Drilling Plans

Mammoth is conducting follow-up mapping and extensive sampling to refine drill targets, aiming to commence drilling in the coming months. This will be concurrent with extensional drilling at the Buster Trend and initial drilling at the Imperial Gold Project, recently secured through an option agreement. The company expects to provide further updates including assay results from reverse circulation (RC) drilling and underground sampling across multiple prospects.

This announcement builds on Mammoth's recent progress at Excelsior, including significant gold intercepts along the Buster Trend and advancing the Imperial Project acquisition, as detailed in the company's March 2026 update on expanding gold zones and project footprint. These developments reinforce the district-scale potential of the Excelsior Project and Mammoth's strategic positioning in a key US mining jurisdiction.

Historical Context and Geological Setting

The Excelsior Project encompasses 226 mining claims, including patented and unpatented claims on federal land managed by the Bureau of Land Management. Historical mining and exploration have documented significant past production and numerous shafts, adits, and prospecting pits across the tenure. The geological setting is complex, involving multiple orogenic events and intrusions that have created a variety of mineralisation styles, including high-sulphidation epithermal and carbonate replacement deposits.

Previous exploration by various companies has included drilling, mapping, and geophysical surveys, with some historical data indicating high-grade mineralisation but limited modern verification. Mammoth's current work aims to systematically evaluate and expand upon these historical findings with modern exploration techniques and rigorous assay protocols.