Red Mountain Mining Ltd (ASX: RMX) — Exceptional Metallurgy Delivers 51.8% Antimony Concentrate at Oaky Creek

25 May 2026

Price Sensitive Announcement $

Highlights:

Pilot crush, grind and flotation study of a bulk sample from Oaky Creek North has produced a high-grade 51.8% antimony concentrate with 85% recovery — well above the 30–40% commercial grade threshold, making it an excellent feedstock for pyrometallurgical processing into saleable antimony metal
The ~20kg bulk sample was collected from shallow historical surface pits at Oaky Creek North and is broadly representative of the orogenic antimony mineralisation exposed at surface
The bulk sample returned a head grade of 19.9% Sb and 0.25ppm Au, consistent with previous rock chip results of up to 39.3% Sb and 1.09ppm Au across the Oaky Creek prospect
Arsenic returned a below detection result of <0.01% As — a significant positive, suggesting this deleterious element is present in very low concentrations at Oaky Creek
Mineralogy is dominated by quartz (50.5%) and stibnite (25.2%), with other sulphide and telluride phases rare at just 0.05% — a clean, simple ore profile that responded exceptionally well to standard flotation
Five priority targets defined across the 3km Oaky Creek corridor are ready for testing in the upcoming RC drilling program, recently approved by the NSW Resources Regulator
Due diligence at the Pioneer Tungsten Project in Montana is progressing well and on schedule

Overview:

Red Mountain Mining has delivered an outstanding metallurgical result from its 100% owned Armidale Antimony-Gold Project in the Southern New England Orogen of New South Wales, with a pilot flotation study producing a 51.8% antimony concentrate at 85% recovery from high-grade Oaky Creek North surface material.

The study was completed by Auralia Metallurgy using standard sulphide flotation reagents, a coarse grind of P80 = 212µm and just 14 minutes of total flotation time — producing a composite concentrate well above commercial grade. The near-zero arsenic content of the concentrate (197ppm As) further underscores the quality of Oaky Creek’s mineralisation and removes a key processing concern common to many antimony projects.

With detailed TIMA mineralogical analysis confirming stibnite (25.2%) as the dominant antimony-bearing phase and minimal penalty elements present, the metallurgy points to a straightforward, low-complexity processing pathway if a sufficient resource is defined. The result comes ahead of an approved 32-hole RC drilling program set to test five high-priority orogenic antimony targets across a compelling 3km mineralised corridor — analogous to Larvotto Resources’ (ASX: LRV) Hillgrove Project, Australia’s largest known antimony deposit.