Copper price dropped almost 2% on September 29 and is close to its lowest level in six and a half years.
The price 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.
Goldman Sachs 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 2016.
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 emphasized on September 28 when shares in commodities trader and miner Glencore dived 30%.
Crude oil has fallen some 60% from June 2014, thermal coal has been on a long 60% slide since 2011, and iron ore is down even more, close to 70% since 2010.
The effects are rippling out into other sectors. On September 29, Japanese shipping business Daiichi Chuo Kisen Kaisha filed for protection from creditors, caused by the collapse in Chinese demand for iron ore and coal.
Unsurprisingly the collapse sent a shiver through the rest of the Japanese shipping sector. Nippon Yusen, Mitsui OSK Lines, Kawasaki Kisen Kaisha saw their shares fall between 4% and 8%.
The effects spread far wider than the mining companies and their support services.
Any economy dependent on commodity exports is seeing its currency punished.
Australia, whose iron ore, coal, oil and natural gas fuelled the Chinese boom, has seen its dollar lose more than a quarter of its value against the US dollar over the past year.
Chile, where copper makes up 30% of the value of its exports, is expected to announce on September 29 that public spending, having grown almost 10% last year, will rise by half that amount this year.
Economic growth there has slowed along with the fall in the copper price and a decline in investment in the mining sector.
For smaller countries the effect can be catastrophic.
On September 28, Zambia’s currency, the kwacha, fell more than 17% – its biggest one-day fall on record – as prices for its copper exports dived again. Copper accounts for 85% of Zambia’s exports.
The kwacha recovered on September 29 but it is down 45% on the year.
It has also been hit by the news that Glencore, Zambia’s second largest employer after the government, might make further cuts at its Mopani Copper Mines there. Last week, it announced it would lay off more than 3,800 workers.
Ratings agency Moody’s cut Zambia’s sovereign rating on September 25, making it more expensive to borrow in the international markets.