Copper prices have sunk to a six-month low, retreating almost 20 per cent to $7,150 a tonne on Tuesday, since hitting a record high of $8,930 a tonne in early July, as the red metal suffers a severe case of summertime blues.

Sentiment towards copper, the benchmark industrial commodity, has been dented by the sharp fall in oil prices, the dollar’s revival and broader concerns about the global economic outlook.