NEW YORK —  Gold prices briefly plunged below $800 an ounce Thursday as investors continued to sell off commodities on concerns that the economic slowdown will dramatically reduce demand for energy and raw materials.

Gold for December delivery fell $34.90 to settle at $804.50 an ounce on the New York Mercantile Exchange after earlier falling to $786.70.

Other precious metals also fell. December silver fell 54.5 cents to settle at $9.635 an ounce on the Nymex, while December copper lost 12.5 cents to settle at $2.0855 a pound.

Jon Nadler, analyst with Kitco Bullion Dealers Montreal, blamed the pullback on investor expectations of a substantial drop in worldwide demand for commodities.

"If the global economy will have to go through what apparently lies ahead of it, hopes for demand for 'stuff' will have to be sharply revised _ and not upward," Nadler said in a note.

In energy trading, crude oil fell below $70 after the government reported sharp increases in U.S. crude and gasoline supplies, a sign investors took as more evidence that the slumping economy is curbing demand.

Light, sweet crude for November delivery dropped $4.69, or 6.2 percent, to settle at $69.85 a barrel on the Nymex, the lowest settlement prices since Aug. 23, 2007. Earlier prices dipped to $68.57, a level not seen since June 27, 2007.

Crude has now fallen 52.5 percent since surging to a record $147.27 on July 11.

In other Nymex trading, heating oil fell 10.62 cents to settle at $2.1108 a gallon, while gasoline futures lost 16.02 cents to settle at $1.622 a gallon.

Meanwhile, agriculture futures traded mixed on the Chicago Board of Trade.

Wheat for December delivery fell 0.5 cent to settle at $5.5525 a bushel, while December corn lost 3.5 cents to settle at $3.845 a bushel.

November soybeans rose 9 cents to settle at $8.670 a bushel.

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