Copper prices and related exchange traded funds (ETFs) have been dragged down on concerns that the massive quake in Japan could have affected the country’s ability to smelt copper. Still, hopeful observers note that rebuilding Japan could uplift industrial metals.

The iPath Dow Jones-UBS Copper Subindex Total Return ETN (NYSEArca: JJC) fell around 6% last week, reflecting the recent drop in copper futures prices, which has worried observers since copper is viewed as a leading economic indicator, writes John Spence for MarketWatch. [A Mixed Forecast for Copper ETFs.]

Copper could experience its biggest decline since June 2010 “on high energy prices and concerns of a slowdown in China.”

Copper ETFs like First Trust ISE Global Copper (NASDAQ: CU) and Global X Copper Miners (NYSEArca: COPX) have diminished. The materials sector ETFs, including SPDR Materials Select Sector Fund (NYSEarca: XLB), iShares Dow Jones U.S. Basic Materials Sector Index Fund (NYSEArca: IYM) and First Trust Materials AlphaDEX Fund (NYSEARca: FXZ), have also taken a hit.

Additionally, lower copper prices have dragged down the iShares MSCI Chile Investable Market Index Fund (NYSEArca: ECH) – Chile is the world’s largest copper exporter.