"It is a very difficult decision to leave, but next year I will be entering my seventh year as chief executive," Carroll said in a company statement.

"I feel that the time will be right to hand over to a successor who can build further on the strong foundations we have created."

Anglo American said that Carroll, a US citizen aged 55, would remain in the post until the appointment of a successor.

The announcement of her decision to stand aside comes a day after Anglo American slashed its forecast for annual platinum production amid deadly strikes at the group's troubled South African operations.

Earlier this week, Carroll urged South African authorities to restore order, as violent mining strikes raged.

Last week, she met South Africa's mining and finance ministers as a mass strike for wage increases cripples production at Anglo American's platinum unit.

"It has been a great honour to lead Anglo American," Carroll said in the statement that made no reference to the current problems in South Africa.

"I am extremely proud of everything we have achieved during my period as chief executive and I will always retain enormous admiration and affection for this great company and its outstanding people."

Her tenure has taken in the global financial crisis and a boom in demand for commodities, especially from the world's second-biggest economy China.

"Under Cynthia's leadership, after a record (earnings) year in 2008, the group successfully weathered the global financial crisis," Friday's statement said.

"In 2011, Anglo American again achieved record profits... enabling it to enter the current economic downturn in a strong position."

Carroll took the helm at Anglo American in 2007 after 18 years in the aluminium industry with Alcan, including five as president and chief executive of its primary metals arm.

Her appointment as head of Anglo American was the first time that the 95-year-old company had appointed an outsider to the top job.

Anglo American chairman John Parker said that Carroll had had "a transformational impact" on the group.

"She developed a clear strategy, based on a highly attractive range of core commodities, and created a strong and unified culture and a streamlined organisation with a focus on operational performance.

"Her legacy will include, among many other things, a step change improvement in safety, sustainability and the quality of our dialogue with governments, communities and other stakeholders," Parker added.

Investors welcomed news of Carroll's departure, sending Anglo's share price up 1.99 percent to 1,894.5 pence in late morning deals on London's FTSE 100 index of leading companies, which was down 1.05 percent.

"We expect this announcement to be greeted positively by the market, given that it will lead to speculation about a potential restructuring of the business or takeover," said Jonathan Jackson, head of equities at brokers Killik & Co.

Carroll's departure meant that only two out of the 100 companies trading on London's benchmark FTSE index would be led by female chief executives.

British publisher Pearson said earlier this month that its chief executive Marjorie Scardino was stepping down, leaving Burberry's Angela Ahrendts and Imperial Tobacco's Alison Cooper as the only female bosses of FTSE 100 firms.