Three-month London copper future prices were also feeling the pain. Prices fell to their lowest in six years at $4,787.50 a ton. LME Copper is now down around 25 percent since January.
It's caused global jitters, as copper is traditionally seen as the "canary in the coalmine" for global growth. However, Julian Jessop, head of commodities research at Capital Economics, said he expects the copper story to improve.
"It may take some better news on China's manufacturing sector to turn sentiment around, but that should not be too long in coming," he wrote in a research note.
"Confidence in China is... showing some signs of recovering as more policy stimulus is introduced, at least judging by the rebound in the equity market," Jessop added, saying he expects a further recovery in prices, with
He now forecasts copper prices will reach $5,500 per ton by year-end 2015, and $7,000 by the end of 2016.