Key Highlights

  • A maiden Ore Reserve of 420,000 tonnes at 2.34 grams per tonne gold for 31,600 ounces has been declared at Rose Hill.
  • The reserve is classified as Proved and Probable at a 1.3 g/t cut-off.
  • It is backed by a pre-feasibility study completed in July 2026 using a gold price of A$4,500 an ounce.
  • The planned Mining method is long-hole open stoping with pillars.

Maritana Minerals (ASX:MRT) has declared a maiden Ore Reserve for the Rose Hill underground deposit, about half a kilometre south-east of Coolgardie in Western Australia. The reserve totals 420,000 tonnes at 2.34 grams per tonne gold for 31,600 ounces, classified as Proved and Probable at a 1.3 g/t cut-off.

The figures were contained in a replacement announcement lodged on the evening of 3 November. Maritana said the amendment corrected Competent Person statements and minor drafting errors and did not change the reported resources or reserves.

The addition lifts the company's group Ore Reserves to 235,600 ounces. Proved Reserves account for 70,000 tonnes at 2.14 g/t and Probable for 350,000 tonnes at 2.37 g/t.

Why a reserve is a different milestone

A Mineral Resource is an estimate of gold with reasonable prospects of eventual extraction. An Ore Reserve goes further: mining, processing and cost assumptions have been applied and the material shown to be economic. Only Measured and Indicated resources can be converted, so Rose Hill's 194,000 tonnes of Inferred material at 4.53 g/t, holding about 28,000 ounces, sits outside the reserve as potential upside at depth.

The reserve is backed by a pre-feasibility study completed by Mining Plus in July 2026, using a gold price of A$4,500 an ounce and 91% processing recovery. The planned method is long-hole open stoping with pillars. The cost model shows free Cash Flow of about A$24.5 million over 26 months, although the JORC table separately cites an underground mine life of roughly 23 months. Those figures are estimates, not guaranteed future returns.

The cut-off question

Maritana has re-reported the underground resource at a lower 1.0 g/t cut-off, giving 524,000 tonnes at 4.49 g/t for about 76,000 ounces. Under the previous 2.0 g/t cut-off the resource held roughly 74,900 ounces, so the change added few ounces because the grade-tonnage curve is relatively flat between those levels.

The reserve itself uses 1.3 g/t, down from 1.63 g/t in a 2022 pre-feasibility study. The company says wider mineable shapes at the lower cut-off added tonnes and ounces and improved overall margin, citing a stronger gold price and optimisation work. That reasoning depends on gold prices; a materially lower price would test the assumptions.

The open-pit component of the Rose Hill resource is unchanged at 287,000 tonnes at 1.99 g/t for 18,000 ounces, reported at a 0.5 g/t cut-off. Combined with the underground material, the total Rose Hill resource stands at 810,000 tonnes at 3.61 g/t for about 94,000 ounces. The reserve therefore converts roughly a third of the contained resource ounces at this stage, which is typical for an early underground study that excludes Inferred material and applies dilution and mining losses.

The Black Swan connection

Rose Hill is not a standalone project. Ore would be trucked about 85 kilometres to Maritana's Black Swan facility, where conversion of a former nickel plant to gold processing is underway. Maritana is targeting first gold in the second half of calendar 2027.

Managing director Grant Haywood said the reserve confirmed that Rose Hill stood up economically and moved the project a meaningful step closer to development. The modest size and short life mean Rose Hill is better seen as one feed source for the hub rather than a company-defining asset.

What to watch

Key risks include the timing and cost of the Black Swan conversion, haulage costs and the remaining approvals. Maritana plans further drilling at depth to define the orebody better and convert Inferred material to Indicated, which could extend mine life if successful.

Investors should look for progress on plant conversion milestones, any development decision for Rose Hill and how additional ore sources are sequenced to keep Black Swan supplied beyond Rose Hill's roughly two-year life.