Mount Gibson’s flagship operation, Koolan Island is in the Buccaneer Archipelago 140km north of Derby. Acquired through the takeover of Aztec Resources Ltd in 2007, the former BHP mine boasts Australia’s highest grade hematite Ore Reserves which average over 65% Fe. Mount Gibson completed recommissioning of the former BHP mine and commenced shipments in April 2007. Mining was interrupted in late 2014 when the Main Pit flooded but continued in satellite pits until early 2016. Production and sales of high-grade hematite recommenced in April 2019 following a two-years seawall reconstruction and mine refurbishment program. As of July 2024, Mount Gibson had exported in excess of 38Mt of ore from Koolan Island(Operations – Mt Gibson Iron, n.d.).
The mineralised zone of the main deposit is an overturned enriched haematitic sandstone horizon within the Yampi Sandstone Member unconformably overlying the Elgee Siltstone. It is between 12 and 30 metres thick, approximately 2,000 m in length and is currently modelled to approximately 215 m in depth below mean sea level. and dips 55 to 80o to the south.
The Acacia East Deposit mineralised zone is an enriched haematitic sandstone horizon within the Yampi Sandstone member unconformably overlying the Elgee Siltstone. It is between 8 and 20 metres thick, and dips 45 to 60o to the south and is 1,500m in length and approximately 300 m in depth.
The Mangrove Deposit mineralised zone is an enriched haematitic sandstone horizon within the Yampi Sandstone Member unconformably overlying the Elgee Siltstone. It is between 12 and 30 metres thick. The mineralised unit is overturned and dips from 80o to the south in the west, twisting to right way up and 80o to the North in the east and is approximately 1,000m in length and approximately 250 m in depth(Major Mines & Projects | Koolan Island Mine, n.d.).
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References:
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Major Mines & Projects | Koolan Island Mine. (n.d.). Retrieved June 23, 2025, from https://miningdataonline.com/property/815/Koolan-Island-Mine.aspx
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Operations – Mt Gibson Iron. (n.d.). Retrieved June 23, 2025, from https://www.mtgibsoniron.com.au/operations/
