Glasgow University Archaeological Research Division (Guard) said it may have been dropped by a hunter.
It added that it may have arrived from elsewhere and then been lost by a local collector or a teacher at the former parish school in Durness.
The 3cm relic was made from a sedimentary rock called black chert.
In a report by Guard made available on Highland Council’s Highland Historic Environment Record, archaeologists said the find had “cast an unexpected light” on the area’s prehistoric times.
The spot on rocky ground between two lochs was a perfect place to stalk game, they said.