• Mineral Resource Estimate (MRE) for the Oracle Ridge Project in Arizona increases substantially to 28.2Mt at 1.35% copper, 11.06g/t silver and 0.16g/t gold using a 0.8% copper cut-off grade for 380,000 tonnes of contained copper
  • Represents a 27% increase in contained copper at 1% cut off compared to the previous MRE with a 20% increase in tonnes and 6% increase in copper grade
  • Higher confidence measured and indicated categories account for more than half of the new MRE – and the grades are better too
  • Eagle Mountain Mining confident it has the foundations to become a mid-tier copper producer


Special Report: More than half of Eagle Mountain Mining’s newly upgraded resource for its Oracle Ridge copper project in Arizona sits in the higher confidence measured and indicated categories.

This month marks the fourth anniversary of Eagle Mountain Mining’s (ASX: EM2) acquisition of the Oracle Ridge project, about 30km north-east by air of Tucson.

Copper was first discovered in the area in 1873 with primary production at Oracle Ridge taking place between 1991 and 1996. Approximately 1.1mt of ore was produced over that period.

EM2 has largely focused on extensional, infill and upgrade drilling since the first major exploration program Oracle Ridge in September 2020. Underground mapping and channel sampling work has dominated the company’s focus since January this year.

Drilling and channel sampling data acquired since the last resource update in October 2022 has been incorporated into the new Oracle Ridge estimate of 28.2Mt @ 1.35% copper, 11.06g/t silver and 0.16g/t gold for 380,000t of contained copper.

Today’s resource update was based on a lower 0.8% copper cut-off grade, compared to 1% used in the October 2022 estimate, following internal mining and metallurgical studies.

On a like-for-like basis, it represents a 27% increase in contained copper, 20% uplift in tonnes and 6% higher grade to the previous MRE declared for Oracle Ridge.


Road to 400,000t contained copper

Using the 0.8% cut-off grade, EM2 has boosted the copper metal content at Oracle Ridge by 57% since delineating its first resource for the project in December 2020.

The Oracle Ridge inventory now hosts 15.3Mt @ 1.37% copper, 12.35 g/t silver and 0.18g/t gold for 209,000t of contained copper in the higher confidence measured and indicated categories.

It is worth noting the copper grades for the measured (1.4%) and indicated (1.36%) are also higher than the average total resource grade of 1.35% copper.

The new MRE benefited from extensive new geological information gained from accessing historical underground workings at Oracle Ridge.

This included 50 additional drill holes from surface and underground, almost 1km of high detail underground channel sampling and updated geological modelling.

EM2 chief executive Tim Mason declared the company on track to surpass more than 400,000t of contained copper at Oracle Ridge.

“This update is a key milestone on our path to become a significant producer of copper, with a strong focus on low emission production,” Mason said.

“Our recent refurbishment of the underground mine was instrumental to this latest update, as it provided us with previously unrecognised insight into the geology and mineralisation and has confirmed the mining and processing optionality of the project.

“In particular, we see greater opportunity for a much larger mining operation at Oracle Ridge, than previously contemplated, leveraging off recent advancements in processing and mining technologies to reduce both costs and our impact on the environment.”


‘Foundations to become a mid-tier copper producer’ 

Based on the success off the underground mapping and sampling completed this year, as well as the potential of surrounding prospects and mines on the perimeter of Oracle Ridge, a deposit-wide surface mapping program is being planned.

EM2 is eyeing a low-grade, large tonnage operation at Oracle Ridge and all current and upcoming activities are based on that desired processing pathway.

More than 600,000t of contained copper remains available at lower cut-off grades, which will be assessed as part of ongoing mining and processing technical evaluations.

Mason said considerable growth potential exists within several targets not included in the new MRE. These include up to 10% copper in outcropping surface samples along a 3.5km zone directly east of the resource and up to 4% copper in prospective sediments 500m to the west, including at the historical Hartman-Homestake mine.

Potential mineralisation has also been identified below the Leatherwood intrusion.

“The resource remains open in multiple areas and we are confident that further resources will be defined,” Mason said.

“We are currently assessing and prioritising resource extension targets, along with upgrades of existing inferred resources to further de-risk production in the first five years of mine life.

“Taking all this into consideration, I am optimistic that we have the foundations to become a mid-tier copper producer at Oracle Ridge.”



This article was developed in collaboration with Eagle Mountain Mining, a Stockhead advertiser at the time of publishing.

This article does not constitute financial product advice. You should consider obtaining independent advice before making any financial decisions.