Pieces of Bronze Age flint are a relatively common find among archaeologists hunting for artefacts in the north-east.
But keen relic hunter Andrew Cockburn could not believe his luck when he stumbled across his latest discovery.
Taking part in a field walk at Crathes, near Banchory, he spotted a rare Bronze Age knife hidden among the rocks and dirt.
On closer inspection he found it was a highly unusual polished-edge knife – possibly used as a ceremonial piece.
Mr Cockburn, from Huntly, is a member of Ofars Archaeology – a society for north-east residents with an interest in historical artefacts.
He said: “The knife was a special find, it’s very rare. When you find something like that you know immediately it’s special.”
The knife was carved from flint found along the Buchan coast and is suspected to be about 4,000 years old.
Though archaeologists regularly discover flint pieces, the vast majority are scraps of wasted material discarded when tools were being made.
Significant pieces can be claimed by the Crown as having national interest and any new findings must be submitted to the Treasure Trove unit in Edinburgh.
After examining the knife, the committee agreed it was a special find.
Mr Cockburn decided to forego the option of a reward because he would rather the money was used for further research.
Jenny Shiels, of the treasure trove unit said: “This is a good example of a prehistoric knife made from local reddish-brown north-east flint. Objects such as this made from a local source are particularly interesting. The knife has been allocated to Marischal Museum in Aberdeen, which has the largest collection of prehistoric objects from the north-east. The Scottish treasure trove system is unique in the UK and ensures all objects of antiquity are claimed by the Crown on behalf of the nation and cared for in Scotland’s museums for public benefit.”