JERSEY, Channel Islands — The largest haul of Celtic coins ever found in northern Europe, thought to be worth millions of pounds, has been dug up by amateur treasure hunters on the Channel Island of Jersey.

About 50,000 silver and bronze coins dated to around 50BC were discovered by Reg Mead and Richard Miles, who have been searching the same field for 30 years, The Guardian reported.

The pair had been inspired by local legends of buried treasure and scoured the area using a metal detector. Earlier this year they found 60 silver coins and one gold, dating from the 1st century BC.

But they were convinced there was further fortune waiting for them, and so they continued searching.

Their jackpot discovery, a mass of coins clumped inside a soil block, weighs almost a ton (three quarters of a tonne). It has been removed from the ground and taken to a safe place.

Further excavation is taking place at the secret location by archeologists keen to get to the bottom of the ancient discovery, while it is kept secluded from the threat of looters.

Ownership and value of the findings could take months to determine and are subject to the island’s Treasure Act. It is estimated the coins could be worth £10 million (US$15.6 million).

Olga Finch, curator of archaeology at the Jersey Museum, called it a find of international importance. “The fact that it has been excavated archaeologically is also rare and will greatly enhance the level of information we can glean about the people who buried it. It is an amazing contribution to the study of Celtic coins.”

Jersey Heritage said the coins are from Armorica — modern day Brittany and Normandy — and made by a tribe called the Coriosolitae, The Independent reported.

The coins are understood to date back to the Late Iron Age, a time when the armies of Rome’s Julius Caesar were advancing north-westwards through France, driving the tribal communities towards the coast.

People escaping would have crossed the sea to Jersey, finding a place of refuge away from Caesar’s campaigns. It is thought they may have buried their wealth to protect it.