Copper futures prices settled at their lowest level in three months Friday after briefly touching a 14-month low amid signs that stockpiles of the metal are expanding due to slack industrial demand.

On other commodity markets, precious metals also fell; oil futures rose; grains and soybeans were mixed; and livestock and meat futures were mixed.Copper futures settled 1.30 cents to 3.40 cents lower on New York's Commodity Exchange with the contract for delivery in May down 3.10 cents at $1.033 a pound, the lowest daily settlement for near-term copper deliveries since Jan. 24.

The May contract price dipped to $1.0305 during the session, the lowest near-term copper price since Feb. 13, 1990. Copper last traded below $1 a pound in early February 1990.

The decline extended a slide that began late in the third quarter of 1990, when slowing industrial production translated into weakening demand for copper. The metal is widely used in the construction, automobile and electronics industries.

Traders disregarded Friday's government report of an improvement in the unemployment rate last month and focused instead on a 5,800-ton rise in London Metal Exchange warehouse stocks and a no-strike vote by unionized workers at the Chile Copper Co.'s El Teniente mine division.

Steve Platt, metals analyst at Dean Witter Reynolds Inc., said further selling was prompted by the market's failure to rally on news that producer Gecamines of Zaire declared force majeure on 1991 shipments of refined copper, meaning the company will not meet its delivery commitments.

Since stockpiled supplies are abundant, "many people feel it's not going to make much of a difference," Platt said.