It has delivered a 500% boost to the Rare Dyke rare earth elements estimate to 397 million tonnes grading 0.33% total rare earth oxide and 4.2% phosphate for 1.3Mt of contained TREO, including 280,000t of contained neodymium-praseodymium, plus 16.7Mt phosphate.
RareX estimates a basket price for the resource's elements of A$33/kg.
The company opened to split resource updates for its Rare Dyke and adjacent Phos Dyke targets due to delays in assay results.
A significant increase in the phosphate is expected from the Phos Dyke resource due next month.
Without Phos Dyke, Cummins Range is now the second largest undeveloped Australian rare earths deposit, and now sits comfortably with Lynas Rare Earths' nearby Mt Weld mine, and Arafura Rare Earth's Nolans project in the Northern Territory.
RareX opted to use a 2.5% phosphate cut-off to define economic mineralisation over TREO given its improved understanding of the system.
Phosphate is expected to be both sold as a fertiliser, but offers potential as a feedstock for lithium iron phosphate batteries
The phosphate resource has grown 800%. Cummins Range also contains "appreciable quantities of niobium and scandium".
Indicated resources are put at 44Mt at 6.3% phosphate, mostly in the upper 100m of a resource that extends down hundreds of metres.
RareX started a prefeasibility study last year, suggesting a $430 million development, but has paused all work given the rapid increase in scale.
A revised scoping study is instead being considered.
RareX acquired Cummins Range in 2019, and the large, deep carbonatite pipe has swiftly become the company's focus. It has expanded the resource by 1000% since.
Cummins Range remains open in all directions.
The area was previously explored by Navigator Resources and Kimberley Rare Earths.
Navigator estimated a maiden open pit resource of 1.1Mt at 3.5% for 38,500t in 2008.