Gold Fields chairwoman and anti-Apartheid activist Mamphela Ramphele is leaving the South African gold major to “further her socio-economic and political work,” according to a company statement. She has served the Johannesburg-based company since 2010.

In stepping down, Ramphele is reportedly forming a party challenging the African National Congress, which has ruled one of the world’s biggest mining countries since the end of Apartheid rule in 1994; non-executive director Cheryl Carolus will take over. “I am pleased that during my tenure at Gold Fields progress has been made entrenching sustainability of the company’s operations,” said Ramphele, who spent seven years under house arrest for anti-Apartheid activities.

One of the world’s largest unhedged gold producers, Gold Fields produces 3.5 million gold equivalent oz annually from mines in Australia, Peru, Ghana and South Africa.