Core Lithium’s Finniss reserve lift: mine design and scheduling notes for planners
Reviewed by Tom Sullivan

First reported on Australian Mining
30 Second Briefing
Core Lithium has reported a substantial ore reserve increase at its Finniss lithium project in the December 2025 quarter, materially extending mine life and supporting higher spodumene concentrate output from the Grants open pit and BP33 underground deposits. The updated reserve, derived from infill drilling and revised pit and stope designs, is based on a conventional dense media separation plant near Darwin Port, with trucking distances kept short to reduce logistics costs. For geotechnical and mine planners, the larger reserve base supports longer-term pit slope optimisation, underground sequencing, and potential plant debottlenecking studies.
Technical Brief
- Similar hard‑rock lithium operations may benchmark Finniss’ reserve update workflow for integrating infill drilling with rapid design revisions.
Our Take
Lithium pieces in our database increasingly sit alongside multi-commodity ESG discussions, such as the Vatican meeting with Sigma Lithium and major miners on 26 January 2026, signalling that projects like Finniss in Australia will be scrutinised not just on output but on social and environmental performance.
Within our 758 Mining stories, lithium projects like Core Lithium’s Finniss tend to be earlier-stage or scale-up assets rather than long-life incumbents, so a reserve uplift typically improves financing options and can shift a developer into the peer group of more bankable Australian hard‑rock operations.
For Australian lithium projects tagged under ‘Projects’ in our coverage, reserve growth has often preceded changes in mine plans or processing configurations, suggesting Finniss may also see optimisation studies or staged expansions to capture the enhanced resource base.
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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