Accidental Archeologists Dig Up Treasure Troves of Ancient Artifacts : History: Valuable discoveries are often made on private property by unwitting excavators. But regulating serendipitous finds is usually difficult.

Abir Nassee was battering a corner of the mud-and-concrete wall in his Old City art gallery, trying to clear out a niche so that he could install a safe.

Suddenly his sledgehammer struck something that refused to crumble. Puzzled, Nassee cleared away rubble.

Behind the new opening in the shop’s wall he discovered a large, brownish-white stone, about 3 feet wide and 2 feet high. Nassee suspected, and authorities later confirmed, that it was part of the wall that had surrounded Jerusalem at the time of King Solomon, about 3,000 years ago.

Half a world away, writer Paul Elliott was planting vegetables outside his home in a Virginia suburb of Washington, D.C., when he began to unearth fragments of strangely smooth, reddish-brown stones.

Besides the usual harvest, Elliott’s garden yielded a bumper crop of quartzite remnants from 4,000-year-old tools.

A gallery owner and a gardener hardly fit the romantic image of Indiana Jones poking around pyramids or searching for a mysterious scroll.

But, in fact, said George E. Stuart, the National Geographic Society archeologist, “many discoveries, often valuable ones, are made by accident.”

Atop a hill near Rome, picnickers spot the ruins of a town that had been razed after a battle in 492 B.C. and sought by archeologists for centuries.

On a field in Suffolk County, England, a retired gardener unearths a box containing gold bracelets, decorative silver tableware and nearly 15,000 Roman coins--believed to have been buried by a wealthy family 16 centuries earlier and now worth more than $2 million.

Such accidental archeology offers a variety of rewards.

“Sometimes I sit in awe, looking at the stones of the old wall,” said Abir Nassee. “I am excited to think that my ancestors maybe helped to build it.”

An excavation of Elliott’s yard “changed a lot of what we knew about prehistoric life in the area,” said Mike Johnson, an archeologist for Fairfax County, Va. “We thought people had stayed primarily along the rivers, but this put them smack dab in the interior.”

Under Britain’s treasure-trove law, the Suffolk gardener may pocket the financial gains from his cache.

Despite their value and importance, however, chance discoveries evoke pleas for caution from professional archeologists.

“You must remember that the real value is not in the item itself, but in what it tells us about the past,” said Rudolph Cohen, deputy director of the Israeli Antiquities Authority. “That story can be lost if the discovery is not handled properly.”

Proper handling generally means leaving the site undisturbed--at least until an experienced archeologist can examine it.

“If people just pick up what they find, willy-nilly, it’s very hard to tell anything,” warned Frank McManamon, chief of the U.S. National Park Service’s archeological assistance division. Many artifacts, he said, “have been witnesses to the unfolding of human history. But they become mute when divorced from their original context.”

Most information, McManamon said, comes from studying the relationships of objects--to each other, to the soil, to the people who used them.

For example, tests on a pristine fragment of a prehistoric bowl may reveal what plants were kept in the bowl. This, in turn, will help scientists determine what the users of the bowl ate. The strata of ground in which the bowl was found offer clues to its age.

The potential for great gain and loss in serendipitous discoveries is illustrated by one of the archeological marvels of the 20th Century, the terra-cotta army of Xi’an in southeastern China.

In 1974, peasants digging a well on a commune near the site uncovered a tunnel filled with life-size clay models of male heads, pieces of arms and torsos, metal arrowheads and other items.

Stories are told of children taking pottery home to play with and of peasants offering the clay heads and other artifacts for roadside sale for $2.50 each. Fortunately, there were no buyers.

The peasants had been instructed at commune meetings to report all chance discoveries to authorities. In time, archeologists excavated the site. What emerged were lifelike soldiers and horses in battle formation, made 22 centuries earlier to guard the tomb of China’s first emperor, Qin Shi Huang.

China isn’t alone in strictly regulating ancient finds. Most countries with vast archeological treasures, such as Israel, Italy, Egypt and Mexico, generally forbid private excavations and make all antiquities the property of the state, including those found on private property.

U.S. laws, tightened after a wave of looting and desecration of Native American burial sites, ban the removal, buying and selling of artifacts from public lands and grave sites.

But for the most part, Americans may keep what they find on their own property. In the United States and other countries, looting and vandalism continue because the laws are hard to enforce.

“What we really need,” said McManamon, “is greater cooperation between the public and professionals.”

That kind of cooperation occurred after Paul Elliott made his back yard discovery. He informed the Fairfax County archeology office, which organized a dig in which schoolchildren, college students and other volunteers participated.

Federal, state and local agencies, as well as the Society for American Archeology and other groups, are making many such efforts to work with communities. The Arkansas Archeological Society offers seminars and field programs for interested amateurs.

“The best answer would seem to lie in public education,” the National Geographic Society’s George Stuart wrote, “so that people can know of our rich collective past and the threats to it.”