Copper prices rose Tuesday, buoyed by a weaker dollar and rising prices for oil.

Copper for September delivery closed up 2.4% at $2.1755 a pound on the Comex division of the New York Mercantile Exchange.

The Wall Street Journal Dollar Index, which measures the dollar against a basket of 16 currencies, was recently down 0.3% at 87.20, as investors took profits on the dollar after several days of sharp gains.

A weaker dollar tends to buoy copper, which is priced in the U.S. currency and becomes more affordable to foreign investors when the dollar falls.