NEW YORK (AP) -- The prices of gold, most other metals and crude oil fell Wednesday, following the stock market down, as unrest grew in Europe and uncertainty lingered about the world economy.

Gold for December delivery fell $12.80 an ounce to finish at $1,753.60 an ounce. Gold has pulled back this week after a summer-long rally took it from about $1,550 an ounce to almost $1,800 an ounce on expectations that stimulus measures would be imposed in Europe and the U.S. to help boost economic growth.

Benchmark crude fell below $90 as protests raged in Greece and Spain over spending cuts and tax increases designed to resolve a debt crisis. Oil finished the day at $89.98 per barrel, down $1.39.

Police fired tear gas at rioters hurling gasoline bombs and chunks of marble during Greece's largest anti-austerity demonstration in six months. At least 38 people were arrested and 64 injured in protests in Spain.

The protests in Europe shattered a relative calm and raised investor fears that the region still does not have control of its three-year-old debt crisis, despite a bold plan by the European Central Bank to buy bonds of indebted countries.

The unrest in Europe led traders to abandon risky assets, said Sterling Smith, a futures specialist with Citi in Chicago.

With U.S. economic figures "mixed at best," he said, global economic concerns are also taking a toll, and what he called the "half-life" of the Federal Reserve's latest efforts to help the economy is getting shorter.

In other metals trading, silver for December delivery dropped 0.8 cent to $33.94 an ounce and December copper fell 4.85 cents to $3.71 per pound. Palladium fell $15 to $625.85 per ounce.

Platinum for October delivery rose $2.60 to $1,634.40 per ounce. Disruptions to South Africa's mining sector, where miners have been striking for weeks, worsened. South Africa produces 75 percent of the world's platinum.

In energy trading, heating oil fell 0.18 cent to $3.1068 per gallon, wholesale gasoline rose 11.4 cents to $3.0811 per gallon and natural gas rose 9.9 cents to $3.023 per 1,000 cubic feet.

Key agricultural contracts finished the day lower. December wheat fell 17.25 cents to $8.6925 per bushel, December corn fell 19 cents to $7.2475 per bushel and November soybeans fell 38.5 cents to $15.73 per bushel.

Copyright 2012 The AP.