About 6,000 years ago, a stone ax that had been skillfully carved and shaped by Native Americans was lost on a ridge overlooking the Potomac River in Virginia. The ax, about 7 inches long, had been hewed and smoothed and was narrowed at one end where a wooden handle attached. Its loss must have been keenly felt.

On Oct. 12, Dominic Anderson and Jared Phillips, 17-year-old high school seniors from Ohio, were on an archaeological dig at George Washington’s estate at Mount Vernon when a stone that looked like a big potato turned up in their sifting screen. Not sure what it was, they asked the Mount Vernon archaeologists working nearby.

It was the ax, which had been lost for 60 centuries.

Mount Vernon announced details of the find this week. They said it was a major discovery that helps take the story of the site far beyond its place as the home of the first U.S. president.

It “provides a window onto the lives of individuals who lived here nearly 6,000 years ago,” said Sean Devlin, Mount Vernon’s curator of archaeological collections. “Artifacts such as this are a vital resource for helping us learn about the diverse communities who shaped this landscape throughout its long history.”

Mount Vernon officials said the ax was made from a piece of “green stone” probably taken from a local river.

It had been chipped with a hammer stone to create a cutting edge and then further carved with a harder stone to create a smoother cutting surface.

It was then worked even further with a grinding stone, and the groove was cut where the handle would attach. The tool was probably highly valuable.

Devlin said the ax was dated through knowledge of when such tools came into use, by comparing it to other tools from the period, and by dating the methods of its construction. It is believed to be the first such artifact found at Mount Vernon in recent years.

The makers of the ax were probably people who migrated by boat up and down the Potomac River seasonally and might not have lived in fixed villages, Devlin said. The ax would have been a key possession.

“When you spend the effort to make tools like this ax, you would have probably carried it with you,” he said. “You wouldn’t just make something like this off the cuff … and used it once or twice and chucked it. … This is something people invested time in. It definitely isn’t something that was just sort of pitched by the side, just by happenstance.”

The ax was probably used for cutting or carving wood, he said. It probably was not a weapon.

“It’s always fantastic to go out there and see something that’s so evocative,” he said.

The ax was found by students from Archbishop Hoban High School in Akron, Ohio. Fourteen students, headed by archaeology teacher Jason Anderson, were helping map the dimensions of what is believed to be a cemetery for Mount Vernon’s enslaved African-Americans and their descendants.

But the area is relatively pristine and has many prehistoric artifacts, according to Joe Downer, Mount Vernon’s archaeological field research manager.

Downer said Dominic Anderson, the teacher’s son, and Phillips, the second student, called out to him when they found the ax.

“Is this anything?” Downer said they asked.

“I was kind of taken aback when I saw it,” he said. “I looked at it, and I held it for a minute, and I was like, ‘Well, that might be one of the coolest things we found out here.’ ”

“It’s pretty unmistakable when you see it,” he said.

Jason Anderson, the teacher, said the school’s students have been doing archaeology work at Mount Vernon for six years.

“It’s not a field trip,” he said in a telephone interview. “The students are working. This isn’t just kind of kick back … and have a fun time. It’s a lot of work, but it’s very fulfilling work.”