Swiss archaeologists have thanked a fruit-and-vegetable farmer for uncovering a massive trove of 1,700-year-old silver and bronze coins.

He made the spectacular discovery back in July, when he spotted a molehill in his Cherry orchard, revealing many shimmering green coins.

The trove of more than 4,000 bronze and silver coins dates back to Ancient Rome and weighs 15 kilos (33 pounds). It was discovered in Ueken, in the northern canton of Aargau, and it took months of discreet excavations to unearth the find.

Archaeologists said the coins' imprints remain legible, allowing an expert to determine that they date back to Ancient Rome, stretching from the rein of Emperor Aurelian (year 270-275) to that of Maximilian (286-305).

"The orchard where the coins were found was never built on. It is land that has always been farmed," archeologist Georg Matter told Agence-France Presse, adding that treasure was probably stashed away shortly after the coins had been minted.

The farmer is in line for a finder's fee but will not be able to keep the coins, many of which contained an unusually high silver content, as they will be put on show in a local museum.

The archaeologists believe their original value must have been at least a year or two of wages.

The remains of an early Roman settlement were discovered in a dig in the nearby town of Frick a few months earlier.

mm/bw (AFP, AP)