Authorities in the Norfolk County district attorney's office recovered about 1800 ancient coins that were stolen from the Fogg Museum in 1973.

William G. Delahunt, Norfolk County district attorney, said yesterday investigators found the coins in a duffle bag and a fishing tackle box buried under pipes and debris in a South Shore community. He declined to give the exact location.

He said an informer--whom he declined to identify--told him in December 1978 that some of the coins were located in his jurisdiction.

The coins, some of which date back nearly 2500 years, are part of a collection valued at between $2 and $13 million that the Fogg used for teaching purposes, Delahunt said. "The coins are almost impossible to appraise because many are extremely rare," he added.

About 4000 coins which were stolen in the 1973 heist are currently on display in the Fogg, a museum spokesman said yesterday. Authorities recovered these coins in 1974 in Rhode Island and Montreal, Delahunt said.

He said Canadian authorities have informed him that a portion of the collection has already been sold on the black market, but he added he is "hopeful" that investigators from Norfolk and Middlesex counties and the state police may soon recover the remaining 700 to 1000. Authorities are working on leads from the same anonymous source, he said.

Delahunt said police did not arrest anyone in connection with Saturday's recovery.

Three persons, including a former Widener Library security guard, were convicted in 1976 of armed robbery and sentenced to prison terms ranging from 15 to 30 years for stealing the collection.

David G. Mitten, curator of ancient art at the Fogg and James Loeb professor of Classical Art and Archaelogy, was unavailable for comment yesterday.