An adventurous treasure hunter claims he has found a legendary lost gold mine in the mountains of northeastern Utah – a $1.7billion bonanza first discovered by Spanish priests in 1650 that has laid dormant for more than three centuries.

Gary Holt believes that he and his son have found the Josephine de Martinque mine at Hoyt’s Peak in the Uinta Mountains – and they only need federal government permission to delve deep enough to claim their prize, the Park Record newspaper reports.

The Lost Josephine Mine was fabled to be the richest gold mine in the world. It was first documented by Spanish Jesuit priests in 1650.

Discovery: Brandon Holt, pictured, and his father Gary say they have found an abandoned Spanish gold mine from the 1600s

The U.S. Forest Service is skeptical, saying the cavern is likely a natural formation and that it contains no gold deposits

The explorers say they have found calcite semi-precious gemstones in the cavern, but no gold

But U.S. Forest Service officials say the mine is a fairy tale – and treasure hunters are defacing a natural cave and destroying formations that are millions of years old as they search for riches.

Mr Holt told the Park Record that he has yet to find gold in the cavern.

He obtained a mining permit and said he has so far pulled millions of dollars worth of calcite crystals from the shaft. He markets them as ‘Goldite’ and says they could become valuable as semi-precious gemstones.

So far, though, the spelunking into the cavern has not yet yielded any gold. Mr Holt remains undeterred. In a 2009 post on the treasure hunter forum Ancient Lost Treasures, Mr Holt suggests that the mine could contain $1.7billion in gold.

Officials say the ‘Goldite’ mining operation is little more than a ruse to allow Mr Holt to continue looking for gold.

The caver is at the bottom of a deep shaft that Mr Holt and his friends have been exploring for years

This is a ‘Goldite’ outcropping – calcite that Mr Holt believes he can sell for millions as a semi-precious stone

Revolution: The mine was abandoned by the Spanish in 1680 during the Pueblo Revolt when Indians drove them from their claims in New Mexico

He says the hunt for gold is ‘still in active development.’

References to the the Lost Josephine Mine first appear in records of Spanish Jesuit priests in 1650. It was said to be the most valuable gold mine in the world.

Three decades later, the priests were forced to abandon the mind when the Spanish were driven out of the New Mexico Territory during the 1680 Pueblo Revolution uprising by the Pueblo Indians.

The exact location of the mine has been lost ever since.

But, Forest Service Archeologist Tom Flanagan, says the the myth of the Lost Josephine Mine being in northeast Utah is nothing but a fairy tale.

‘If we had those kinds of gold mines in the Uintas (Mountains), I’d be a rich man,’ he told the Park Record.

‘A lot of treasure hunters will map on a natural solution cavity and try to purport that it’s a historic or ancient mine and then try to mine it.’