The price of copper dropped almost 2% on Tuesday and is close to its lowest level in six and a half years.
The metal fell to $4,955 a tonne, just $100 above the level it reached in 2009 in the wake of the financial crisis.
Demand for copper, which is used across industry from construction to car manufacturing, has suffered from the slowing Chinese economy.
Investment bank Goldman Sachs warned investors this week that prices would continue to fall.
In a note entitled, “Copper’s bear cycle still has years to run”, its analysts predicted copper prices would probably drop to $4,800 a tonne by the end of December and to $4,500 by the end of next year.
The decline in copper is only a part of a global meltdown in commodity prices caused by China’s economic downturn.
The depth of the slump was emphasised on Monday when shares in commodities trader and miner Glencore dived 30%.
Four years after the group went public in the UK’s biggest stockmarket flotation, analysts at Investec warned that weak commodity prices could lead to the firm’s equity value being “eliminated”.
Crude oil has fallen some 60% from June last year, thermal coal has been on a long 60% slide since 2011, and iron ore is down even more, close to 70% since 2010.