U.S. President Donald Trump announced on Wednesday a new 50% tariff on copper to start on August 1 in a bid to promote domestic development of an industry critical to defense, electronics and automobiles.

U.S.-listed mining stocks are rising. Freeport-McMoRan, the largest miner by market value, added 2.6% to $46.76 in premarket trading. Southern Copper gained 2.3% to $102.25. Newmont, which is also a major producer of gold, was up 0.6% to $59.10.

Manufacturers and construction companies — as well as consumers — would face higher prices if the U.S. jacks up tariffs on copper, analysts said.

President Trump’s 50% tariffs on copper, due to start August 1, are causing unusual distortions in the metal markets. Copper is now 25% more expensive in New York than London. And there’s a rally in copper scrap.