A group of amateur treasure hunters unearthed millions of dollars worth of ancient Celtic coins on the Channel Island of Jersey.

Around 50,000 silver and bronze coins dating back to 50 BC were discovered by Reg Mead and Richard Miles, two amateur metal detectorists.

Before the big find in 2011, the pair who have been searching the same area for over 30 years, found 60 silver and one gold coins dating from the 1st Century BC.

Convinced there was more treasure they continued their search and recently discovered the mass of coins inside a soil block which weighs almost a ton.

“We are talking about searching for 40 to 50 hours to get these coins out, and every one gives you the same buzz," said Mead.

Further excavation is taking place at the secret location which is now being led by Philip de Jersey, an Oxford University authority on Celtic coins.

The ownership and true value of the items could take months to determine and are are subject to the island's Treasure Act. They are estimated to be worth around $13 million.

Commenting on the find Olga Finch, curator of archaeology at the Jersey Museum, said it was 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. We already have a number of very important Iron Age coin hoards found in the Island, but this new addition will make Jersey a magnet for Celtic coin researchers," Finch told the Guardian.

De Jersey described the find as exceptional, "certainly the largest hoard of Iron Age coins ever found, not just in Jersey but the whole of the Celtic coin-using world … it is difficult to come out with a figure much below 50,000 coins given the volume of the block."

The coins are said to be in excellent condition and are believed to be from Armorica, modern Brittany and Normandy.

Originally published in 2011.