Fortescue Metals Group Ltd. said the company’s chief executive officer of its iron ore division, Fiona Hick, had resigned after less than six months in the role.

Hick, who joined the company from oil and gas producer Woodside Energy Group Ltd., will be replaced by Dino Otranto, the company’s chief operating officer for iron ore. Otranto, a former Vale SA executive, will head up the metals business, while Mark Hutchinson will remain chief executive of the green energy arm.

Hick’s sudden departure was “friendly and mutual,” the company said in a statement on Monday.

Fortescue is the world’s fourth-biggest iron ore miner, and aspires to become a major producer of green hydrogen and other clean-energy technologies. Earlier this year it restructured the company to create two CEO roles, one for the vast iron ore operations and the other running the new energy arm. Both report to the company’s chairman and founder, billionaire Andrew Forrest.

Hick said in the statement she was thankful “for the opportunity and wished Fortescue well in its mission to decarbonize.” She didn’t say what she would do next.

(Updates with more details on Fortescue from fourth paragraph)