Antofagasta produced 284,700 metric tons of copper in the first half, down 3.7% from the same period in 2023.
Fortescue is revising plans to become a major green hydrogen producer, citing high energy costs as main reason for restructuring and layoffs.
Jackson, who is the current president of National Grid Ventures, an energy group, joins Rio Tinto on September 1.
The world's largest listed miner said iron ore output from Western Australia on a 100% basis was 76.8 million tonnes in the three months to June 30.