• Ark Mines has a maiden indicated resource of 21.7Mt at 1,419ppm monazite equivalent at Sandy Mitchell
  • The resource is in the higher confidence indicated category and has the grade to support strong project economics
  • Magnet REEs make up 24% of the TREO basket
  • The project takes up just 1.2% of the available anomaly area


Special Report: A maiden resource at the flagship Sandy Mitchell rare earths-mineral sands project of 21.7Mt at 1,419ppm monazite equivalent “significantly exceeded our expectations”, Ark Mines says.

The Sandy Mitchell rare earths and heavy minerals project, hosted in fine sands known as terrestrial placer deposits, is 300km west of Cairns in northern QLD.

Placer deposits are a shallow style of mineralisation where grains of a valuable mineral like gold or rare earths are mixed with sand deposited by ancient rivers or glaciers.

Unlike deeper hard rock deposits or ionic clays, they tend to require simpler processing methods because they are easy to handle and don’t require large amounts of energy or clean water to liberate the minerals of value from the mullock.

An independent metallurgical review earlier in May shone a light on the mineralogy of Ark Mines’ (ASX:AHK) asset, concluding it would be ‘highly amendable’ to simple, low-cost beneficiation such as gravity processing.

Beneficiation test work already completed delivered concentrates with grades of up to 51.9% total rare earth oxide, a sign that the material is suited for refining by standard sulphuric acid baking refiners.


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The Sandy Mitchell project. Pic: Ark Mines


Resource “exceeded our expectations”

AHK has now brought the Sandy Mitchell project up to new heights with the definition of the maiden indicated resource, making it the first surface-expressed placer REE deposit with a JORC resource on the ASX.

The company has also skipped past the usual step of first defining an inferred resource straight to the indicated stage, giving it a resource that supports mine planning right out of the gate.

Furthermore, the reported monazite equivalent grade of 1,419ppm is expected to support strong project economics through simple low-cost downstream processing, with reference to current market prices for monazite concentrate.

This is particularly true since valuable magnet REEs – neodymium, praseodymium, dysprosium and terbium – make up 24% of the total rare earth oxide (TREO) basket.

There is also plenty of room for further growth as the resource takes up just 1.2% of the available anomaly area at Sandy Mitchell.

“This maiden MRE has significantly exceeded our expectations. We have consistency in grade from surface to basement for a basket of high value minerals including combined heavy mineral grades of 13,450ppm,” Ark Mines executive director Ben Emery said.

“The commercialisation pathway for Sandy Mitchell is now more clearly defined, given the fact it is the simplest REE style of deposit to mine and beneficiate.

“Importantly, the MzEq grades of 1,419ppm are also indicative of potential commercial scale based on current market prices for monazite concentrate.

“In addition, the MRE was achieved from a target drilling area which accounts for just 1.2% of the available anomaly area at Sandy Mitchell, providing plenty of scope for additional exploration upside.

“We are also pleased to have the resource in an Indicated category, which bodes well for our upcoming pre-feasibility study and the mineral licence application.”


More growth coming

While the Sandy Mitchell resource is hugely positive, there is potential for growth in the coming months with the company looking to incorporate the results of its Stage 2 drill program into an updated resource estimate.

The updated resource estimate will form part of AHK’s forthcoming pre-feasibility study for the Sandy Mitchell project, which is scheduled to be completed before the end of the 2024 calendar year.



At Stockhead we tell it like it is. While Ark Mines is a Stockhead advertiser, it did not sponsor this article.


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