A wooden mallet inlaid with the initials "A.L" was made by Abraham Lincoln, who used it during his Indiana youth to make furniture, Indiana State Museum officials said Tuesday in unveiling the artifact that had been a family's secret heirloom for five generations.

It's a rare relic that can be directly tied to the 14 years that Lincoln and his family lived in Indiana, said Dale Ogden, the museum's chief curator of cultural history.

The tool, called a bench mallet, is inlaid with square-edged nails that form Lincoln's initials — "A.L" — with a period separating them, while a series of other nails were driven into the tool to form the year "1829."

Lincoln, who would have been about 20 when it was made, would have used it to drive hand-carved wooden pegs into the simple Federal-style furniture he and his father made on the frontier.

The 11-inch-long mallet will go on display at the downtown Indianapolis museum on Friday, Lincoln's birthday.

Museum President and CEO Tom King called the mallet an "incredible discovery" that's moving because it was crafted "by Lincoln's own hands."

Ogden said he's certain of the mallet's authenticity because the family that still owns it and has loaned it to the museum for one year has exhaustive documentation.

The tool has descended through the family of Barnabas Carter, who was among the earliest settlers in Spencer County, a southwestern Indiana county that abuts the Ohio River. The Carters were neighbors of the Lincolns after Thomas Lincoln moved his family to Indiana in 1816. The Lincolns remained in Indiana until 1830, when they moved to Illinois when the future 16th president was 21.

Steve Haaff, who's an expert on the furniture that Thomas Lincoln and his son made, said the mallet was "the best-kept secret in Spencer County.

"No one knew about it."

He said Lincoln apparently made it from a larger tool called a splitting maul, which was used to drive metal wedges into logs to split them, after that tool's head broke in half.

In the more than 150 years since Lincoln's assassination, other tools and furniture with the initials "A.L." have periodically surfaced that may have been owned by Lincoln — or anyone else with the same initials.

"This story is different because it was apparently kept in one family for several generations and they were neighbors of the Lincolns," said James M. Cornelius, curator of the Lincoln Collection at the Abraham Lincoln Presidential Library & Museum in Springfield, Illinois. "That's a key element of the provenance of this. It's just a fascinating case."