A spokesman for the United Mine Workers said yesterday the union is "reconciled to a strike" on Dec. 6 although it will resume negotiations here Friday for a weekend of bargaining with the Bituminous Coal Operators Association.

A strike has been widely anticipated for some time, but this was the first time the union has predicted without qualification that an agreement cannot be reached in time to avert a walkout the UMW's 160,000 Eastern miners.

"It would appear that a strike is inevitable," said the spokesman, who said he was reflecting the views of the union's bargaining team, including UMW President Arnold Miller. Miller was out of town yesterday and unavailable fo comment.

Asked why negotiations are continuing if a strike is inevitable, the spokesman said, "I guess there is always hope." He said there was no talk now of a contract extension but one might be considered if there is a complete turnaround" in the talks. There is a feeling now of no progress at all," he added.

Although the UMW-BCOA contract does not expire until Dec. 6, the union says it would take 10 days for miners to ratify a new contract, meaning the negotiators would have to reach an agreement by this weekend.

The union's no-progress assessment differs somewhat from that of the BCOA, which reported some progress yesterday on health and safety provisions.

But the bargainers reportedly remain far from agreement on health and pension benefit guarantees, which, along with the union's demand for a right to strike over local grievances, remain the biggest obstacle to a settlement. The importance of the benefits issue was underscored Tuesday when Miller announced that medical and death benefits would be cut off, and pension benefits reduced, if the union went out on strike. Normally these benefits continue during a strike.