US President Donald Trump signed an executive order imposing a 50 per cent tariff on certain copper imports – notably excluding refined copper – on Wednesday, sending US copper prices tumbling by around 20 per cent to US$4.44 a pound as of Thursday afternoon.The move clarified the scope of Trump’s initial announcement in early July, which had led US futures prices to rally to a record high of nearly US$6 and prompted traders to accelerate shipments in anticipation of widespread duties.In this...