The price of crude oil is close to an eight-month low as traders worry about ramped-up exports from Iran and Libya adding to a global supply glut.
Oil for February delivery fell 92 cents to close at $91.80 in New York.
Some economic sanctions against Iran could be eased after a plan announced Sunday to implement an agreement to allow inspectors to monitor the country's nuclear program.
A rebound in Libyan production is also pushing oil prices lower.
Gold rose $4.20, or 0.3 percent, to $1,251.10 an ounce. Silver rose 16.2 cents to $20.385 an ounce.
In March agricultural contracts, corn rise 1.75 cent to $4.345 a bushel, soybeans rose 15.75 cents to $12.9425 a bushel and wheat rose 4.5 cents to $5.735 a bushel.