The actively traded March contract for silver fell 71 cents, or 3 percent, to $21.25 an ounce. Gold for April delivery declined $14.70, or 1 percent, to $1,328 an ounce.
Janet Yellen will appear before Congress Thursday for the second time since taking over as head of the U.S. central bank earlier this month from Ben Bernanke.
Investors will be watching to see if Yellen's comments suggest any changes to the Fed's plans to gradually wind down its bond-buying program. The purchases had been bullish for gold investors who feared the purchases would weaken the dollar and cause inflation.
In other trading of metals futures, platinum for April delivery fell $13.50, or 1 percent, to $1,429.10 an ounce, and palladium for March delivery fell $4.60, or 0.6 percent, to $731.50 an ounce.
Copper for March delivery edged down a penny to $3.24 a pound.
Crop prices were mixed.
Wheat for May delivery fell 12.5 cents, or 2 percent, to $6.055 a bushel, May corn edged down a quarter of a cent to $4.61 a bushel and May soybeans edged up 10 cents, less than 1 percent, to $13.97 a bushel.
Energy futures mostly rose.
The price of oil rose as U.S. oil supplies increased less than expected. Natural gas prices fell on expectations for warmer weather by the middle of March.
Crude oil for April delivery rose 76 cents to $102.
The Energy Department said crude oil supplies rose by 68,000 barrels last week, well below the increase of 1.5 million barrels expected by analysts surveyed by Platts.
Natural gas fell 15 cents to $4.54 per 1,000 cubic feet.
Wholesale gasoline was unchanged at $2.80 per gallon and heating oil rose 2 cents to $3.13 a gallon.