A worsening outlook for global growth and a stronger dollar are sending the price of copper lower.
Copper logged its biggest decline in more than a month, falling 1.1 percent to finish at $3.6445 a pound.
The European Central Bank warned of another gloomy year for the 17 countries that use the euro. The bank said it now expects the euro zone's economy to contract 0.3 percent next year, versus its previous forecast for 0.5 percent growth.
The price of copper, which has many industrial uses, tends to track the outlook for global growth.
The dollar also advanced against the euro and other currencies, further weighing on the price of copper. Commodities are typically priced in dollars, and fall if the U.S. currency strengthens.
Gold and silver edged higher.