Great Boulder Resources (ASX:GBR) high grade structure emerging at Eaglehawk

Great Boulder Resources (ASX:GBR) has reported a substantial new mineralised interval at the Eaglehawk deposit within the Side Well Gold Project near Meekatharra.

The new drilling result confirms the presence of a high grade structure that appears to influence gold distribution within the broader Mulga Bill to Eaglehawk corridor.

Managing Director Andrew Paterson discusses the significance of the result, how it fits into the developing geological model, and what comes next for exploration and resource planning.

What is the significance of the 105m at 2.41g/t Au intersection at Eaglehawk?

The intersection of 105 metres at 2.41 grams per tonne gold from 95 metres in hole 25EHRC040 provides confirmation of a continuous mineralised interval linked to an interpreted northwest trending structure at Eaglehawk.

The mineralisation contains several distinct high grade intervals, including 3 metres at 18.85 grams per tonne from 102 metres, 13 metres at 5.17 grams per tonne from 114 metres and 6 metres at 5.08 grams per tonne from 180 metres.

These higher grade intervals are consistent with the position of west dipping vein sets, indicating that the structure is influencing gold grade distribution.

“Within the 105m of mineralisation there are discrete higher-grade intervals which appear to correspond to known west-dipping veins.”

This same structure hosts the previously reported intersection of 6 metres at 121.07 grams per tonne gold in hole 25EHRC003.

The latest drilling represents the first targeted test of the structure using drilling oriented toward the northeast, confirming the effectiveness of that approach and providing direction for follow up drilling.

How does this new zone affect the upcoming Mineral Resource Estimate?

Eaglehawk is not currently included in the existing Side Well global Mineral Resource Estimate of 668,000 ounces at 2.8 grams per tonne gold.

A maiden resource for Eaglehawk will be included in the next global Mineral Resource update scheduled for December 2025.

This resource will include all drilling up until early October, and hence this new result represents upside for the next resource update.

The new intersection will support that process once further drilling has defined the geometry and continuity of the structure.

Eaglehawk forms part of a larger intrusive related system spanning more than three kilometres of strike from Mulga Bill to the northern extent of Eaglehawk.

Along with Saltbush and Side Well South, it contributes to the exploration target range of 272,000 to 465,000 ounces.

When considered alongside the existing Mineral Resource, this supports a near term expectation of between 940,000 and 1.1 million ounces subject to drilling outcomes and resource classification.

What are the next steps for drilling and follow up?

The next stage of drilling will aim to define the thickness, strike length and orientation of the high grade structure confirmed in hole 25EHRC040.

Several additional reverse circulation holes are already being designed to follow up the result.

A diamond rig currently on site is also expected to drill deeper into the high grade zone to collect structural information, which will assist in refining the geological interpretation.

“We will optimise intersection angles with ongoing drilling, and as our understanding grows it will help us target other similar structures.”

Air core drilling continues along the northern extension of the Eaglehawk corridor to determine the extent of mineralisation along strike.

The results from these drilling programs will be incorporated into future resource modelling.

How confident are you that this structure is similar to high grade link structures seen elsewhere?

The interpretation is supported by the spatial relationship between the northwest trending structure and the west dipping vein sets, where high grade gold appears to be concentrated.

This structural style is consistent with the Break of Day deposit near Cue, where cross cutting link structures hosted the majority of contained ounces in the 2020 resource estimate.

However, confirmation of the continuity and geometry of the structure requires further drilling and detailed structural logging from diamond core.

“This new high-grade zone is interpreted to have structural parallels to the high-grade link structures at Musgrave Minerals’ Break of Day discovery near Cue which contained the bulk of the gold ounces in that resource.”

This interpretation will continue to be refined as additional geological and drilling data becomes available.

How does this fit within the broader growth plan for the Side Well Gold Project?

Side Well currently contains a Mineral Resource of 668,000 ounces at an average grade of 2.8 grams per tonne gold across the Mulga Bill and Ironbark deposits.

The exploration target of 272,000 to 465,000 ounces across Eaglehawk, Saltbush, Side Well South and other targets supports a near term expectation of approximately 940,000 to 1.1 million ounces subject to ongoing drilling.

The project benefits from its location near existing mining and processing infrastructure in the Meekatharra region, and the ongoing drilling program is supported by a cash balance of more than 16 million dollars.

“This is the first link structure to be specifically targeted by Great Boulder with holes drilled towards the northeast. Over the past few years of drilling at Mulga Bill and now Eaglehawk we’ve consistently seen this system throw up high-grade surprises, so the story continues to get better and better the more we drill.”

Eaglehawk is therefore an important part of the strategy to build high grade resource inventory within trucking distance of infrastructure.

Next phase of exploration

The new drilling result at Eaglehawk confirms a structurally controlled zone of high grade mineralisation and provides a clear focus for upcoming drilling.

Further reverse circulation and diamond drilling will aim to define the geometry of the structure and support the maiden resource estimate for Eaglehawk in the December 2025 global Mineral Resource update.

The result strengthens the broader growth potential of the Side Well Gold Project as work continues across multiple high priority target areas.

Please note the following valuable information before using this website. 

Independent Research 

Market Open Australia is intended to be used only for educational and informative purposes, and any information on this website should not be taken as investment advice or guidance. It is important to conduct your own research before making any investment decisions, which should be based on your own investment needs and personal circumstances. Any investment decisions based on information contained on this website should be taken in line with independent financial advice from a qualified professional or should be independently researched and verified.