Regis Rosemont underground extension: design and scheduling notes for mine planners
Reviewed by Joe Ashwell
First reported on Australian Mining
30 Second Briefing
Regis Resources has extended the known mineralised system at the Rosemont underground mine in Western Australia, with drilling confirming gold mineralisation 600m south of the current Stage 3 resource envelope at the Duketon operations. Resource development drilling is targeting down-plunge and southern extensions of the existing underground lodes, with multiple holes intersecting mineralisation outside the modelled stopes. The results point to potential incremental underground reserve growth and longer mine life, prompting likely updates to resource models, mine design and development scheduling.
Technical Brief
- Rosemont is an underground operation within Regis’ wholly owned Duketon gold project in Western Australia.
- Stage 3 is the current underground resource frame, with new work stepping beyond this envelope.
- Drilling is being executed as resource development rather than pure exploration, feeding near‑term mine planning.
- Down‑plunge targeting implies focus on continuity of existing lode geometries rather than new parallel structures.
- Southern step‑out drilling requires extended underground drill cuddies and longer hole lengths, increasing metre‑cost and time.
- Mineralisation confirmed outside modelled stopes will trigger re‑optimisation of stope shapes and access development.
- Any incremental underground reserve growth is likely to defer backfill and closure scheduling for existing mining fronts.
- Similar brownfields underground gold operations can use this style of step‑out drilling to stage‑gate capital for new levels.
Our Take
Recent coverage shows Regis Resources banking on higher output from the Duketon gold operations by FY27, so any extension of underground mineralisation at Rosemont directly underpins that production guidance rather than relying on external growth options.
Regis’ decision to step back from the contested Vault Minerals transaction, as reported in July 2026, suggests a strategic tilt towards organic growth; incremental discoveries 600m south of the current Rosemont envelope fit that pattern of extracting more value from existing Western Australian assets.
Within our 1265 Mining stories, Western Australian gold items like Duketon tend to face less permitting friction than greenfield jurisdictions, meaning positive underground results at Rosemont can usually be translated into mine plan changes faster than for comparable gold projects elsewhere.
Prepared by collating external sources, AI-assisted tools, and Geomechanics.io’s proprietary mining database, then reviewed for technical accuracy & edited by our geotechnical team.
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