Ark Mines (ASX:AHK) reports an updated JORC mineral resource estimate (MRE) of 1.1 billion tonnes (Bt) at 1,120 parts per million (ppm) monazite equivalent (MnzEq) for its Sandy Mitchell Rare Earths Project in Far North Queensland.
The MRE comprises 35.8 million tonnes (Mt) measured @ 1,120ppm MnzEq, 1.04Bt indicated @ 1,120ppm MnzEq, and 19.8Mt inferred @1,120ppm MnzEq, reported at a 1,000ppm MnzEq lower cut-off grade. Ark Mines notes measured and indicated resources represent 98% of the total estimate by tonnage.
According to the company, the estimate represents a 307.6Mt (428%) increase over the October 2024 measured MRE of 71.9Mt @ 1,730ppm MnzEq, with MnzEq formulas and cut-off grades reset.
Based on its review of public reported estimates, Ark Mines says Sandy Mitchell is now the largest rare earth MRE reported under the JORC Code 2012 and hosted in heavy mineral sands derived from a metamorphic basement complex.
Managing Director Ben Emery says it took three stages of resource drilling to increase the defined resource by 2,000%, from 50Mt to 1,100Bt.
“That is the foundation a Prefeasibility Study needs,” Emery points out.
“Just as importantly, the mineralisation has proved to be remarkably consistent. Grades logged and assayed from surface right across an area that has grown from 4km2 to more than 6km2 sit within a narrow range.
“And there is substantial room to grow further — the current resource footprint covers only around 30% of our 19km² tenure.”
The updated MRE incorporates stage three, stage four, and stage five resource drilling programs across mining leases ML100253 and EPM28595. The deposit contains estimated in situ material comprising 508,000 tonnes of monazite, 527,000 tonnes of monazite plus xenotime, 140,000 tonnes of total rare earth oxides plus yttrium, and 254,000 tonnes of zircon.
Total heavy and industrial mineral grades include 1,340ppm monazite, 50ppm xenotime, 670ppm zircon, 80ppm rutile, 240ppm high-titanium leucoxene, 150ppm low-titanium leucoxene, 250ppm altered ilmenite, 270ppm ilmenite, and 2.7% garnet with 1.1% muscovite and 12% biotite mica as potential co-products.
Magnetic rare earth oxides neodymium, praseodymium, dysprosium, and terbium average 90ppm, representing approximately 26% of the TREO basket.
Mineralisation extends from surface to an average sand depth of approximately 11m, making it amenable to free-dig open-pit mining.
For the rest of 2026, Ark Mines intends to complete the IHC Mining metallurgical test work program, release an updated Scoping Study, complete infill drilling in the central southeast area, restate the exploration target, and complete a Prefeasibility Study.
Ark Mines is a critical minerals explorer and developer focused on rare earth elements and battery metals.
Write to Paula Fabe at Mining.com.au
Main image: Ark Mines
