Undated (AP) _ Gold futures prices sank to a seven-year low Monday as a stronger U.S. dollar and weak inflation outlook prompted selling by Arab speculators and overseas producers.

Sharp moves marked the opening of the new year on several other commodity markets as well. Oil futures tumbled; lumber hit a record high; orange juice plunged; grains and soybeans were mixed; and livestock and meat ended mostly higher.

Gold for January delivery fell $4.70 on New York's Commodity Exchange to $328.10 a troy ounce, matching the Jan. 3, 1986, settlement price for near- term deliveries. The more actively traded February contract also dropped $4.70 to $328.40 a troy ounce.

January silver sank 3.7 cents to $3.635 a troy ounce.

Middle Eastern speculators were heavy sellers of gold futures in Hong Kong overnight, which started the slide, according to George Milling-Stanley, precious metals analyst with Shearson Lehman Brothers Inc. in New York.

He said Australian and South African producers joined in, prompted by expectations of still lower prices and by the strengthening U.S. dollar. Gold is bought and sold in dollars on the world market, so a stronger dollar makes gold worth less in terms of other currencies.

Declining crude oil prices also contributed to gold's retreat, said Martin Reichenberg, manager of trading services for the Pegasus Econometric Group in Hoboken, N.J.

Oil prices are a key component in the price of consumer goods, and gold is regarded as an investment hedge against inflation. So lower oil prices tend to discourage investment demand for gold.

Reichenberg said investors bearish on gold probably will try to press the metal's price to $300 an ounce, but he predicted a subsequent turnaround based on signs of economic recovery and the recent strength of lumber prices, another early inflation indicator that reached a record high on Monday.

''In the long term, as we get into this recovery, I see inflation eventually coming up,'' he said.

Crude oil futures were pressured by a sharp drop in heating oil due to unseasonably warm weather forecasts for the Northeast, where heating oil is the main home heating fuel.

Light sweet crude for February delivery sank 46 cents to $19.04 a barrel; February home heating oil plunged 2.03 cents to 55.18 cents a gallon; February unleaded gasoline fell .58 cent to 54.17 cents a gallon; February natural gas plummeted 13.3 cents to $1.554 per 1,000 cubic feet.

Spruce two-by-fours for January delivery soared $13.20 to $297.30 per 1,000 board feet on the Chicago Mercantile Exchange, smashing the record of $287.30 reached in August 1979.

Foul and frigid weather in the Pacific Northwest has slowed harvesting and milling of timber, which already was in short supply at a time when demand is on the rise.

''The trend is still strongly up,'' said Curt Cunningham, president of Pacific Futures Trading Co. in Seattle.

January deliveries of frozen concentrated orange juice plummeted 5.75 cents to 81.25 cents a pound on the New York Cotton Exchange as the period of historically harshest winter weather continued to pass with no threat of frost damage to what is expected to be the largest Florida orange crop in 13 years.

Soybean futures fell sharply on the Chicago Board of Trade after weekend rain brought relief to a key soybean-growing region of Brazil, the world's second-largest producer.

Corn and oat futures also retreated but wheat prices surged amid unconfirmed talk that China and Pakistan were seeking to buy U.S. wheat, analysts said.

Wheat for March delivery surged 7 1/2 cents to settle at $3.61 a bushel; March corn dropped 3/4 cent to $2.15 3/4 a bushel; March oats fell 2 cents to $1.43 1/4 a bushel; January soybeans tumbled 6 cents to $5.62 1/2 a bushel.

Livestock and meat futures ended mostly higher on the Chicago Mercantile Exchange, partly reflecting stronger meatpacker demand for cattle.

Live cattle for February delivery rose .48 cent to 77.60 cents a pound; January feeder cattle climbed .38 cent to 87 cents a pound; February live hogs rose .03 cent to 43.65 cents a pound; February frozen pork bellies rose .07 cent to 37.82 cents a pound.