Mammoth Minerals Targets Bonanza-Grade Nevada Silver and Gold with RC Drilling

Bonanza Grades and a Drill Rig on the Way: Mammoth Minerals Expands Its Nevada Story

Mammoth Minerals Ltd (ASX: M79) has reported a broad suite of high-grade rock chip and grab sample results from the Excelsior Springs Project in Nevada, USA. The Mammoth Minerals Excelsior Springs Nevada drilling results have captured significant attention, with the latest assays across the Imperial and Railroad prospects indicating gold, silver, copper and base metal mineralisation that extends beyond historical workings. Preparation for a reverse circulation (RC) drilling campaign is already in progress.

According to the ASX announcement dated 14 July 2026, site works are underway and a drill rig is expected on site within a week. The programme will focus on the Blue Dick, Imperial and Buster areas, targeting extensions to previously reported bonanza surface mineralisation that includes up to 15,336 g/t Ag, 7.46 g/t Au, 2.53% Cu and 0.31% Sb.

"These latest results have exceeded expectations and reinforced the exceptional prospectivity of the Excelsior Springs Project. The combination of bonanza-grade gold, silver and copper assays from previously unmapped historical workings and outcrops across the Imperial and Railroad Prospects is extremely encouraging and has significantly expanded our pipeline of high-priority drill targets," said Glenn Poole, managing director of Mammoth Minerals Ltd.

A Mineral System Demanding Attention

The latest work at Imperial involved reconnaissance rock sampling across mineralised structures and untested historical mining areas. According to Mammoth Minerals Ltd, the results support a geological model that includes:

• Widespread high-grade gold, silver and copper at surface
• Mineralisation extending beyond historical mine workings
• Multiple structural trends with consistent grades across sampled areas

Poole also highlighted that the company now sees evidence of a large-scale mineral system in the Excelsior Springs area, with characteristics described as similar to the nearby Tonopah West Silver Project (8.29 Mt at 462 g/t AgEq, operated by Blackrock Silver).

These interpretations are based on rock chip and grab samples, which are selective by nature and not representative of average bulk grades. However, the spatial consistency and metal tenor reported from both Imperial and Railroad suggest that the mineralised system extends well outside previously known zones.

The Numbers That Matter: Standout Assay Results

The announcement separates results into gold-dominant, silver-dominant and copper-dominant categories, reflecting the polymetallic nature of the system.

Gold-Dominant Highlights – Imperial Prospect

Silver-Dominant Highlights – Railroad and Imperial Prospects

Copper-Dominant Highlights

Copper percentages above 10% are often associated with massive sulphide-style mineralisation in many districts. In this case, Mammoth Minerals Ltd is reporting these grades at surface, which management interprets as evidence of intense hydrothermal fluid flow along key structures.

For investors, these surface assays represent:

• High metal tenor at multiple points across the project
• A mixture of precious and base metals, which may provide optionality in future economic studies
• Clear justification, in management's view, for the imminent RC drilling programme

The Railroad Springs Target: A Newly Confirmed Trend

To the north-west of the main Imperial claims, Mammoth Minerals Ltd reports that sampling across the Railroad Springs trend has returned consistent, high-grade silver values with supporting gold and base metals.

Key results include:

• 1,631 g/t Ag, 0.3 g/t Au, 0.34% Sb, 3.8% Pb, 1.9% Zn (MREX00888B)
• 1,352 g/t Ag, 0.3 g/t Au, 5.7% Pb (MREX00865)
• 1,323 g/t Ag, 0.2 g/t Au (MREX00897)
• 1,301 g/t Ag, 0.3 g/t Au, 0.26% Sb, 2.2% Pb, 1.65% Zn (MREX00889)

These samples were taken from historical workings that have not been tested using modern drilling methods. The combination of silver grades in excess of 1,000 g/t Ag in multiple samples, associated lead, zinc and antimony, and apparent continuity along the trend supports management's conclusion that Railroad represents a valid structural and geochemical target for follow-up work.

In addition, a previously unidentified zone west of the Imperial area has produced encouraging assays such as:

• 111 g/t Ag, 3.56 g/t Au (MREX00978)
• 289 g/t Ag, 0.16 g/t Au (MREX00974)
• 250 g/t Ag, 0.33 g/t Au (MREX00969)

These results indicate that mineralisation is not confined to the immediate Imperial shear zone, but may furthermore occur in multiple parallel or splay structures, broadening the exploration search space considerably.

Educational Section: Understanding "Bonanza Grade" and Key Exploration Terms

What Does Bonanza Grade Mean?

The term bonanza grade is widely used in precious metals exploration to describe exceptionally high metal concentrations.

Typical guideline ranges are:

• Gold:

  • Many open pit gold mines operate at 1–2 g/t Au or lower.
  • Underground operations often work with 3–8 g/t Au.
  • Grades above 10 g/t Au in samples or drill intercepts are often described as bonanza in an exploration context.

• Silver:

  • Economic silver grades are often in the tens to low hundreds of g/t Ag.
  • Values above 1,000 g/t Ag are considered very high grade.
  • The 15,336 g/t Ag sample reported at Blue Dick is far above typical resource grades.

It is important to note that such high grades in surface samples do not, by themselves, indicate a mineable resource. They do, however, suggest that the hydrothermal system was capable of concentrating metals to high levels. Drilling is consequently required to determine the continuity, thickness and average grade of mineralisation at depth.

Key Exploration Terms Used in the Excelsior Springs Update

• g/t (grams per tonne): A measure of how much metal is contained in one tonne of rock. For instance, 1 g/t Au means one gram of gold per 1,000 kg of rock.

• RC drilling (reverse circulation drilling): A drilling method that uses compressed air to return rock chips to surface. It is generally faster and cheaper than diamond core drilling and is often used for first-pass testing of targets.

• Rock chip / grab sample: Small samples of rock collected from surface outcrops, waste dumps or exposed structures. They indicate whether mineralisation is present but are selective, so they do not represent average grades over wide intervals.

• Channel sample: A sample cut along a fixed length of exposed rock, often across a vein or mineralised zone. It provides a more representative sample over that length than a single grab and is reported as thickness (metres) and grade.

• Polymetallic: Mineralisation that contains several metals of possible economic value at once. At Excelsior Springs this includes gold (Au), silver (Ag), copper (Cu), lead (Pb), zinc (Zn) and antimony (Sb).

For investors reviewing early-stage results from Mammoth Minerals Excelsior Springs Nevada drilling results, understanding these terms helps in assessing potential scale and quality, whilst recognising that further drilling and resource work are required to quantify any future mining potential.

Blue Dick: The Headline Target for Upcoming Drilling

According to Mammoth Minerals Ltd, the Blue Dick prospect remains the primary focus of the imminent RC campaign. The company reports more than 6 km of prospective strike defined by high-grade surface samples and historical workings.

Previously reported priority samples include:

Channel sampling has also been carried out across mineralised structures at Blue Dick, with previously reported results including:

• 0.2 m at 17,582 g/t Ag, 0.75 g/t Au, 1.72% Sb, 2.76% Cu
• 0.50 m at 3,407 g/t Ag, 0.54% Cu, 0.47% Sb

These are continuous channels, so they represent a measured width across mineralisation rather than isolated spot samples.

The ASX announcement stresses that there are no known records of prior drilling or geophysical surveys on the Blue Dick claims. From an exploration perspective, Mammoth Minerals Ltd is therefore about to carry out the first systematic subsurface testing of a high-grade surface system along several kilometres of strike.

Drilling Is Imminent: What Mammoth Minerals Plans Next

The current announcement confirms that RC drilling at Excelsior Springs will focus on three key areas:

1. Blue Dick prospect – Maiden RC drilling along multiple high-grade silver–gold–copper–antimony trends, with more than 6 km of mapped mineralised strike and targets defined by rock chips, channels and historical workings, but undrilled to date.

2. Imperial mine extensions and Railroad target – Drilling planned to test extensions of the historical Imperial mine shear zone, incorporating new structural and geochemical targets generated by the latest sampling, as well as the newly identified Railroad trend.

3. Buster trend and associated anomalies – Testing geophysical and geochemical anomalies along the Buster trend, with preparation of a maiden JORC Mineral Resource for the Buster Mine zone targeted for release later in the current quarter.

Poole noted that prospecting and mapping will continue across the broader claim area during and after drilling to refine the geological model of what the company terms a "metal-rich mineral system".

The Investment Thesis: Scale, Grade and Regional Context

For investors examining Mammoth Minerals Ltd, the Excelsior Springs Project sits within the Walker Lane tectonic zone in Nevada, which has historically produced more than 20 Moz of gold, along with substantial silver.

Several project-level factors outlined in the announcement are relevant:

• Regional pedigree – The Walker Lane hosts well-known deposits such as Comstock (8 Moz Au, 200 Moz Ag), Bullfrog (2 Moz Au) and Tonopah (2 Moz Au), with Excelsior Springs located in the Palmetto Mining District on the eastern margin of this structural corridor.

• Polymetallic potential – The project covers approximately 135 km² of claims, with mineralisation including gold, silver, copper, lead, zinc and antimony across multiple structures and prospects.

• Comparable neighbour – Management has drawn comparisons with the Tonopah West Silver Project, reported by Blackrock Silver to host a resource of 8.29 Mt at 462 g/t AgEq (as at 31 March 2026).

• Upcoming catalysts – First RC drilling at Blue Dick, new drilling across Imperial and Buster, a maiden JORC Mineral Resource for the Buster Mine zone, and ongoing surface prospecting results as additional targets are evaluated.

The eventual significance of the Mammoth Minerals Excelsior Springs Nevada drilling results will depend on whether RC drilling can demonstrate continuity of grade and thickness sufficient to support future resource estimates and, ultimately, economic studies.

Why Investors Should Keep Watching Mammoth Minerals

According to the 14 July 2026 ASX announcement, Mammoth Minerals Ltd has now:

• Confirmed bonanza-grade gold, silver and copper samples across multiple prospects
• Identified an extensive, undrilled high-grade trend at Blue Dick of more than 6 km
• Expanded its target pipeline at Imperial and Railroad, with consistent silver and gold grades beyond historical mine areas
• Progressed site works so that RC drilling is expected to commence within days of the announcement
• Advanced preparation of a maiden JORC Mineral Resource at the Buster Mine zone

For investors following ASX-listed explorers, this combination of early-stage grade, multiple targets within a single project and near-term drilling represents a clear decision point. The upcoming Mammoth Minerals Excelsior Springs Nevada drilling results will provide the first real test of how the exceptional surface grades translate into subsurface continuity and scale.

Ready to Dig Deeper Into Mammoth Minerals' Excelsior Springs Opportunity?

With bonanza-grade surface assays across multiple prospects, a drill rig days away from turning at the undrilled Blue Dick target, and a maiden JORC Mineral Resource on the horizon at Buster Mine, Mammoth Minerals Ltd (ASX: M79) is entering what could be a defining period for the company. Investors seeking to learn more about the Excelsior Springs Project, the upcoming RC drilling programme, and the broader investment case should head directly to the Mammoth Minerals website at www.mammothminerals.com.