(Bloomberg) -- US President Donald Trump’s first wave of copper tariffs will hit imports valued at more than $15 billion last year, highlighting the potential inflationary impact on American buyers.

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Details of the 50% import duties sparked turmoil in the global copper market last week — including a record slump for US futures — because Trump handed a surprise exemption to key forms of the wiring metal. But that still leaves significant trade volumes subject to tariffs.

On Monday, the US Federal Register published a list of exactly what will fall under the 50% levy. It includes semi-processed products — like wires, tubes and rods — worth $7.7 billion last year, plus cabling typically used for phone or internet connections with almost the same value, according to Bloomberg News calculations.

And it doesn’t stop there. The White House ordered officials to come up with a plan in 90 days to slap tariffs on an array of other copper-intensive manufactured goods. Trump dramatically expanded the scope of US aluminum and steel tariffs earlier this year by adding derivative products.

The US copper market is scrambling to understand the implications of Trump’s tariffs, which the president said will help boost domestic output of semi-processed and copper-containing products. He stopped short of tariffs on refined metal — an omission that shocked investors but reflects deep US reliance on imports and a pushback by key American buyers, who feared the duties would drive up costs significantly.

Still, the US took in at least 600,000 tons of semi-finished copper last year, according to the US International Trade Commission. About 35% came from Canada, followed by Germany, South Korea and Mexico each at less than 10%. Refined copper, spared from the levies, amounted to about 900,000 tons and was worth about $8.4 billion.

Tariffs will be levied according to the value of the copper content. That means the “semis” that are almost pure copper will attract a much higher effective duty rate than, say, internet cables where the copper wiring is only a part of the product.

(Updates with country data in penultimate paragraph.)

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