Mammoth Minerals Confirms 700-Metre Buster Gold System Extension at Lunchbox Ridge

Mammoth Minerals Extends Buster Gold System 700 Metres, Opens Up District-Scale Upside at Nevada's Excelsior Project

Mammoth Minerals (ASX: M79) has reported new drilling results confirming shallow gold mineralisation at Lunchbox Ridge, a prospect located approximately 700 metres along strike from the historically drilled Buster Mine Zone at its Excelsior Gold-Silver Project in Nevada. The Mammoth Minerals Excelsior Project Buster gold system extends 700 metres at Lunchbox Ridge, and according to the announcement, these results support the company's geological model and extend the known footprint of the Buster gold system beyond the area where previous explorers concentrated their efforts.

With mineralisation remaining open along strike and down-dip, a second active drilling campaign targeting high-grade silver-polymetallic mineralisation at Blue Dick, and 24 additional drill holes planned across more than 6.5 kilometres of strike, Mammoth appears positioned for a sustained period of exploration newsflow.

New gold intercepts at Lunchbox Ridge confirm system extension

The latest Reverse Circulation (RC) drilling program returned multiple broad, shallow gold intercepts at Lunchbox Ridge, a target generated from geophysics and geochemistry programs conducted late last year but unable to be tested until now due to rig availability, according to the announcement.

Several features are highlighted in the report:

• Shallow depths: The primary intercepts begin from as little as 10.7 metres below surface, a profile management considers compelling for future resource conversion.
• High-grade cores within broader envelopes: Each significant intercept contains a higher-grade central zone, consistent with a feeder-structure geometry where mineralised fluids concentrated within preferred pathways.
• Multiple mineralised zones in a single hole: MEXRC2634 returned two separate intercepts, one near-surface at 32 metres and a second at depth at 164.6 metres, indicating potential for stacked mineralisation.
• 700 metres from the known mine zone: These intercepts sit well outside the historically drilled core of the Buster Mine Zone, with mineralisation reported as open in all directions.

"These latest results are an encouraging development for the Buster Gold Trend, confirming shallow mineralisation at Lunchbox Ridge, approximately 700m along strike from the Buster Gold Mine. This highlights the significant growth potential we see across the Excelsior mineral claim," said Glenn Poole, Managing Director of Mammoth Minerals.

Understanding Carlin-type gold deposits: why does this geology matter?

One of the more important aspects of the Excelsior project is the deposit model Mammoth is pursuing, known as a Carlin-Type Gold Deposit (CTGD). For investors unfamiliar with this style of mineralisation, understanding the classification provides useful context.

What is a Carlin-Type Gold Deposit?

Carlin-Type deposits are large, bulk-tonnage gold systems found predominantly in Nevada, named after the Carlin Trend, one of the most productive gold mining regions in the world. They form when superheated fluids rich in dissolved minerals, driven upward by deep heat sources such as intrusive rock bodies, travel through fault and fold structures and permeate porous limestone host rocks.

As these fluids interact chemically with the limestone, they deposit microscopic gold — often invisible to the naked eye — within iron sulphide minerals known as pyrite. The result can be broad, laterally extensive zones of low-to-moderate grade gold capable of hosting large total ounce inventories.

Why does this matter for Mammoth investors?

• Carlin-Type systems are characterised by district-scale footprints, meaning individual mineralised zones can form part of a much larger system.
• Their geometry, described as broad and shallow-dipping, is generally considered amenable to bulk open-cut mining methods, which can reduce unit mining costs relative to narrow vein deposits.
• The Walker Lane trend in Nevada, where Excelsior is located, has historically produced more than 20 million ounces of gold, according to the announcement, with notable deposits including Comstock (8 Moz Au, 200 Moz Ag), Goldfields (5 Moz), Bullfrog (2 Moz), and Tonopah (2 Moz).

According to the report, evidence supporting the CTGD model at Excelsior continues to build. Diamond drilling completed late last year identified abundant chemical alteration, altered limestone and jasperoid units down to the end of the deepest hole at 227.7 metres, along with significant faulting and breccia zones consistent with large fluid flow, and an intrusive feature north of the Buster Fault that may represent the heat source driving the system.

The broader Excelsior opportunity: more than just the Buster Mine Zone

Historically, exploration at Excelsior was concentrated in a relatively small 2.5-kilometre section of the central Buster zone, where near-surface mineralisation was most accessible. Previous operators drilled 83 RC holes in this area across several decades, progressively defining a near-surface gold zone while largely overlooking the broader project area, the announcement noted.

Mammoth's approach has been to apply modern geophysics, geochemistry and structural geology to understand what is driving the entire system, then test the most compelling targets across the full 135 km² landholding.

The Lunchbox Ridge results represent an early test of this systematic approach. Furthermore, by stepping approximately 700 metres east of the historical drilling focus and confirming shallow gold mineralisation, the company suggests the Buster gold system carries considerable potential for expansion.

Key dimensions of the broader opportunity outlined in the report include:

• Mineralisation at Lunchbox Ridge remains open along strike and down-dip, meaning the current drill results do not define the extent of the system.
• The geological model of multiple mineralised feeder structures intersecting favourable host horizons supports the potential for repetitions of the mineralised system across a wider area.
• Management is reviewing the scope to increase the scale of gold mineralisation across the expanded strike length, with potential to add ounces in areas outside the Buster Mine Zone that have seen minimal drilling.
• A further 24 RC holes are planned across multiple mineralised trends, covering a cumulative strike extent of more than 6.5 kilometres, with scope to expand the program based on results.

Blue Dick Silver Prospect: a high-grade polymetallic story running in parallel

While the Buster gold results headline this announcement, a second active drilling campaign at the Blue Dick Silver Prospect adds further optionality to the Excelsior story.

Five RC holes for 1,100 metres have been completed at Blue Dick, with a further 24 holes planned in a program comprising approximately 5,000 metres of drilling. Samples have been submitted to the laboratory, with initial precious metal results expected within three weeks, according to the company.

The surface and channel sampling results underpinning the Blue Dick drilling program, previously reported by the company, show notable grade and polymetallic complexity.

Channel sample highlights (previously reported)

Rock chip highlights (previously reported)

These are surface samples and may not be representative of broader mineralisation across the prospect, though the grades reported are notable enough to justify the drilling campaign now underway. Field mapping and LiDAR surveys have identified more than 6.5 kilometres of strike across four mineralised trends at Blue Dick.

Importantly, this is described as the first drilling program ever conducted at the prospect, with no known records of previous drilling or geophysical surveys across the Blue Dick claims.

Upcoming catalysts and planned activities

Mammoth enters the next phase of its program with several near-term value drivers converging.

According to the announcement, the pipeline of drill-ready targets across the wider Excelsior claim block continues to be developed, with field teams advancing regional rock chip sampling, soil sampling over prospective trends, and interpretation of recently collected heli-magnetic data.

The investment case: why does Excelsior warrant investor attention?

The Lunchbox Ridge results bring together several threads of the Mammoth investment thesis, based on the information disclosed in the announcement.

1. A large geological system. The Carlin-Type model at Excelsior, supported by geophysics, alteration mapping, structural geology and now drilling, has the architecture consistent with a district-scale deposit. The 700-metre step-out to Lunchbox Ridge, with mineralisation remaining open in all directions, demonstrates potential scale.

2. Shallow, near-surface gold mineralisation. Intercepts starting from as little as 10.7 metres depth present an accessible mineralisation profile. Shallow deposits typically carry lower strip ratios and infrastructure costs if they progress toward development.

3. Limited prior drilling across a large land package. The majority of the 135 km² Excelsior landholding has seen limited or no systematic modern exploration, according to the company. With new geophysical datasets and a refined geological model, Mammoth holds a position of relatively early coverage over most of its own tenure.

4. Two mineralised systems within one project. The Buster gold trend and Blue Dick silver-polymetallic prospect offer two distinct exploration targets within the same project. Blue Dick, with elevated surface sample grades and no prior drilling, represents a target with results anticipated in the near term.

5. Nevada jurisdiction. The Walker Lane trend in Nevada is a well-established gold mining jurisdiction with a long history of deposit discovery and developed infrastructure.

6. Resource potential from an early stage. No JORC-compliant Mineral Resource estimate has yet been defined at Excelsior. As drilling expands the known mineralised footprint across the Buster trend and the Blue Dick prospect begins to yield drill results, the company may be positioned to work toward an initial resource estimate over time.

Why investors are tracking Mammoth Minerals

The Lunchbox Ridge intercepts, according to the company, reflect a geological system behaving in line with Mammoth's model, and consistent with management's view that mineralisation may exist beyond the historically drilled core.

With drilling active at two separate prospects, assay results anticipated from Blue Dick, 24 additional holes planned across a strike extent of more than 6.5 kilometres, and a geological model that continues to be refined with each new dataset, the company is entering what it has described as an information-rich period in its exploration history.

The Mammoth Minerals Excelsior Project Buster gold system extends 700 metres at Lunchbox Ridge, and consequently, this positions the company with a genuinely expanding mineralised footprint at a time when both the Buster and Blue Dick prospects are delivering concurrent newsflow. With the Blue Dick Silver Prospect entering its maiden drilling phase and a multi-prospect program underway in the Walker Lane trend of Nevada, investors may find reason to follow the company's newsflow over the coming weeks and months.

Want to Know More About Mammoth Minerals' Excelsior Project?

With drilling active across two prospects, assay results from Blue Dick imminent, and 24 additional RC holes planned across more than 6.5 kilometres of strike, Mammoth Minerals (ASX: M79) is entering an active period of exploration newsflow at its Nevada Excelsior Project. Investors looking to follow the development of the Buster gold system and Blue Dick silver-polymetallic prospect can find full project details, announcements, and company updates at www.mammothminerals.com.