LONDON (AP) — Shares in U.K.-based mining giant Anglo American surged Thursday after it received a 31 billion-pound ($39 billion) takeover approach from rival BHP Billiton, a deal that would create the world’s biggest copper miner, with around 10% of global output — a hugely lucrative market in the transition to clean energy.

Anglo American’s share price closed up 16% in London after revealing that BHP, the world’s biggest miner, had put forward the “unsolicited” and “highly conditional” takeover proposal. The prospective all-share offer from BHP, which is based in the U.K. and Australia, values each Anglo share at 25.08 pounds.

Anglo American, which owns a majority stake in the world-famous De Beers diamond company, said its board was reviewing the approach from BHP.

BHP said the deal would boost its presence in the copper market, which is seeing demand soar amid the shift towards clean energy, as well as giving it greater access to potash, and coking coal in Australia. Copper is particularly sought after as the metal is used widely in electric vehicles, batteries and charging stations.