An amateur treasure hunter armed with a metal detector has found over 52,000 Roman coins worth $1 million buried in field, one of the largest ever such finds in the UK, said the British Museum.

Dave Crisp, a hospital chef, came across the buried treasure while searching for “metal objects” in a field near Frome, Somerset in southwestern England.

Initially, Crisp found 21 coins, but when he unearthed the pot, he knew he needed archaeological help to excavate them.

The hoard contains 766 coins bearing an image of the Roman general Marcus Aurelius Carausius, who ruled Britain independently from AD 286 to AD 293 and was the first Roman emperor to strike coins in Britain.

Somerset County Council archaeologists excavated the pot — a type of container normally used for storing food — it weighed 160kg (350 pounds) and contained 52,500 coins.

The hoard was transferred to the British Museum in London where the coins were cleaned and recorded.

The coins date from AD 253 to 293 and most of them are made of debased silver or bronze.

Roger Bland, Head of Portable Antiquities and Treasure at the British Museum, told CNN: “Dave [Crisp] did the right thing, he didn’t try to dig it all out. This is the largest ever find in a single pot and the second largest ever [in the UK].

“We think that whoever buried it didn’t intend to come back to recover it. We can only guess why people buried treasure, some buried savings, others because they feared an invasion, perhaps this was an offering to the Gods.”

Bland said the coins were probably worth about $1 million.

Dave Crisp, from Devizes in Wiltshire, told CNN: “At the time when I actually found the pot I didn’t know what size it was but when the archaeologists came and started to uncover it, I was gobsmacked, I thought ‘hell, this is massive.’”

Crisp, who describes himself as a “metal detectorist,” unearthed the pot in April, although the discovery was officially announced on Thursday. Crisp told CNN he would have to split the value of the find with the farmer who owns the field in which he discovered the treasure.

Somerset Coroner Tony Williams is scheduled to hold an inquest on July 22 to formally determine whether the find is subject to the Treasure Act 1996. This would help towards determining a value of the hoard should any individual or organization want to buy it.