• Significant rockfall at Koolan Island Main Pit, no injuries
• Remediating rockfall area and resuming mining deemed not viable due to safety risks
• Operations to be suspended, with 75 staff retained for rehabilitation activities

Mount Gibson Iron Limited has provided an update on the status of its Koolan Island operations following a significant rockfall that occurred on the eastern footwall (island-side) of the Main Pit on 16 October 2025. No personnel were injured in the incident, which had been monitored in advance using the site's continuous radar coverage of pit walls. An exclusion zone was implemented in the Main Pit, and all mining remains suspended. After intensive assessment, including input from external geotechnical specialists, Mount Gibson has determined that remediating the rockfall-affected area and resuming mining is not viable given the safety risks of potential future instability and the time and investment required to mitigate such risks, especially in the context of the operation's limited remaining mine life. Prior to the rockfall, production from Koolan Island was scheduled to conclude around September 2026. Further monitoring will occur during the coming wet season to assess the geotechnical stability of the adjacent footwall areas for potential future access. Mining will remain suspended, and processing operations will continue for the time being given the availability of ore stockpiles to meet near-term scheduled shipments, as well as the potential for additional sales from lower grade stocks previously retained for blending purposes. The company will accelerate progressive rehabilitation activities and retain approximately 75 site personnel for these activities, with approximately 250 redundancies and the loss of 200 contractor roles. Employee entitlements will be paid in full, and support will be made available to all personnel. Net costs associated with this transition are estimated at approximately $30-40 million, including progressive rehabilitation work. The accounting rehabilitation provision for Koolan Island totalled $59.6 million at 30 June 2025, a substantial proportion of which relates to the estimated cost of removing the site's infrastructure, much of which may potentially be retained for future post-mining uses. Mount Gibson's cash and investments balance totalled $473 million at 30 September 2025, and the company does not have bank borrowings. The company has withdrawn its sales guidance for FY26.

The company intends to retain a number of Koolan Island personnel whose skills and experience can be utilised to advance the Central Tanami Gold Project towards a development decision and into production. Various items of plant and equipment from Koolan Island are also proposed to be retained for future use at the Central Tanami Gold Project.