Copper futures tumbled after the Trump administration imposed tariffs on copper imports but carved out an exemption for refined copper.

U.S. President Donald Trump on Wednesday signed a proclamation ordering tariffs on copper imports, citing national security, the White House said. The proclamation imposes a 50% tariff on semi-finished copper products and copper-intensive derivative products as of Aug.

In a flurry of trade news on Wednesday, Trump imposed new rates on copper imports and ended the de minimis exemption.