Metro Mining’s latest JORC update reveals a 69.6 million wet tonne Ore Reserve at Bauxite Hills, reflecting 8.1 million tonnes mined in 2025 with no new resource additions. The high-grade bauxite operation continues as a direct shipping ore mine amid rising silica content concerns.
- Ore Reserves stand at 69.6 million wet tonnes with 49.7% alumina
- Mineral Resources total 107.4 million dry tonnes, down 7 million from 2024
- No new Mineral Resources or category upgrades recorded in 2025
- Mining method remains open-cut direct shipping ore (DSO) with minimal processing
- Environmental and native title agreements remain in place
2025 Mining Depletes Reserves Without New Additions
Metro Mining Limited (ASX:MMI) has updated its Ore Reserves and Mineral Resources for the Bauxite Hills Mine as of 31 December 2025, confirming a total Ore Reserve of 69.6 million wet tonnes with an average alumina (Al2O3) grade of 49.7% and silica (SiO2) at 13.5%. This represents a decline of 8.1 million tonnes from the previous year, reflecting ongoing mining depletion during 2025. Notably, no new Mineral Resources were added, nor were there any reclassifications between resource categories in this update.
The Mineral Resources stand at 107.4 million dry tonnes, down 7 million tonnes from the end of 2024. The entire change is attributed to mining activity, with no exploration success or resource upgrades reported. This steady depletion underscores the company’s focus on efficient extraction from existing deposits rather than expansion, maintaining a consistent grade profile across its resource base.
High-Grade Bauxite Across Multiple Deposits
The Bauxite Hills Mine comprises three primary resource areas: BH1, BH2, and BH6, with BH6 being the largest contributor to reserves and resources. BH6 Ore Reserves total 57.1 million wet tonnes at 49.6% alumina and 13.7% silica, while BH2 and BH1 contribute 10 million and 2.4 million wet tonnes respectively, with slightly varying grade profiles.
The bauxite is characterized as a lateritic, pisolitic deposit with a near-horizontal tabular geometry, averaging 1.3 to 1.6 meters in thickness. The ore requires minimal processing, classified as Direct Shipping Ore (DSO), which Metro ships directly to customers without beneficiation. This simplicity in processing supports low operating costs and aligns with the company’s strategy to maintain a lean operation.
Robust Sampling and Modelling Support Confidence
Metro’s resource estimation follows the JORC Code 2012 standards, supported by dense drilling grids, 80m spacing for BH1 and 160m for BH2 and BH6, and comprehensive sampling techniques including reverse circulation aircore, sonic drilling, and vacuum drilling. Bulk density measurements from sonic drilling underpin tonnage calculations, while assay quality is maintained through rigorous lab protocols and QA/QC procedures.
Geological continuity is reinforced by the tabular nature of the deposit and extensive drilling, with Measured Resources defined within 800 meters of sonic drill holes. The company employs advanced modelling software (Vulcan and Micromine) to integrate geological and assay data, ensuring robust resource and reserve estimates. However, the current update is a depletion report without a full resource model refresh, which may warrant attention in future updates.
Operational and Environmental Framework Remains Stable
The mining operation continues as an open-cut, free-dig process with minor ripping of cemented ore. Metro uses front-end loaders and haul trucks to extract and transport bauxite to port infrastructure, where it is screened and shipped via barge to ocean-going vessels. The company has secured all necessary mining tenements and environmental approvals, including agreements with Traditional Owners and native title parties such as the Old Mapoon DOGIT and the Ankamuthi people.
Progressive rehabilitation is integrated into mining activities, with topsoil directly transferred from new pits to exhausted areas. The company’s approach reflects a mature operation with established infrastructure and social licence to operate.
Market and Pricing Assumptions Underpin Reserve Valuation
Economic assumptions for the Ore Reserve include stable long-term bauxite prices based on China’s import market, current operational costs, and a planned expansion to 7 million tonnes per annum capacity. Metro’s contracts include a fixed-price component and market-linked pricing, with penalties applied for silica content above 12%. Notably, the report flags that silica levels in the product are expected to rise above this threshold from 2030 onwards, potentially affecting pricing and marketability.
This update follows Metro Mining’s recent strong operational performance, including record shipments and profits in 2025, as detailed in their earlier financial disclosures. The company’s capital structure is also in flux, with a proposed 20-for-1 share consolidation pending shareholder approval, a move that could reshape investor dynamics in the near term.
Given the lack of new resource additions and the anticipated increase in silica content, the company’s ability to sustain or grow its resource base will be critical to watch. The interplay between product quality and market demand amid evolving global aluminium supply chains adds a layer of complexity to Metro’s outlook.
Bottom Line?
Metro Mining’s 2025 reserve depletion confirms a stable yet non-expanding resource base, with rising silica levels posing a future market challenge.
Questions in the middle?
- Will Metro Mining update its resource model to reflect changing geological or grade conditions?
- How will increasing silica content beyond 2030 affect product pricing and customer contracts?
- What exploration or acquisition strategies might Metro pursue to replenish or grow its resource base?