Grandson proves there was truth behind an old miner's tale after semi-precious stone lost for 70 years is found Elderly miner promised to reveal location of the Blue John stone to Peter Harrison Mr Harrison has spent 70 years searching for the semi-precious mineral His grandson John Turner finally discovered the stone in the Peak District When an elderly miner claimed to have found a vein of semi-precious stone in 1945, it was dismissed by many as an old miner's tale. John Royse promised to reveal the exact location to Peter Harrison, then 19, but died before he could take him to the site. Now, seventy years after searching, Mr Harrison's grandson has finally discovered the lost seam of Blue John stone in the picturesque Peak District's Hope Valley. Discovery: Seventy years after searching, Peter Harrison (left) and his grandson John Turner (right) have the semi-precious stone in their hands Mr Harrison, who is now 87, and his family spent seven decades searching for the deposit. It was his grandson, John Turner, 21, who finally found the stone after noticing something unusual in the floor of the Treak Cliff Cavern. Mr Turner, who has been learning about mining for Blue John stone, said: 'After an hour of digging through muddy deposits I was amazed to come across an old piece of carpet supported by some wooden batons. 'I couldn't believe my eyes when we pulled away the old carpet and there was this most amazing deposit of Blue John stone. It was right under the ladder that my grandfather put in decades ago. He must have walked over John Royse's old find thousands of times over the years.' John Turner learnt how to mine for Blue John stone after his grandfather told him about the treasure Peter Harrison was told by a miner in 1945 that the rare seam existed in the Peak District Mr Harrison, whose family took over the running of the cavern in 1945, said: 'When my grandson telephoned to tell me that he had found John Royse's old deposit, I couldn't believe it. After all these years it was right under my feet. I'm 87 now and retired years ago but, when I heard the news, I just had to put on my old mining overalls and make the trip back into the cavern to see the deposit for myself. The old miner John Royse was not in the best of health and was retiring. He told me of this fantastic deposit of Blue John he had found and asked me to help him get it out. We planned to return to the cavern the next day but sadly John Royse was taken ill and died. Over the years I have spent countless hours searching for that deposit. Precious: A tray of resin treated Blue John stone found in the Peak District Blue John is made from fluorspar which has reacted with other chemicals to give it its distinctive banded streaks. The mineral was formed millions of years ago, although only a small quantity is allowed to be mined each year. Treak Cliff Cavern has been designated as a Site of Special Scientific Interest and is a show cave featuring spectacular stalactite formations. It is one of only two working Blue John mines in the world, providing the stone for jewellery and ornaments - much of which is hand-crafted in workshops on site. Telling the truth: John Royce in the Treak Cliff Cavern in the 1940s Vicky Turner, Mr Harrison's daughter and Mr Turner's mother, now manages Treak Cliff Cavern. She said: 'I grew up with stories of John Royse's lost deposit. To be honest I thought it might have been a bit of an old miner's tale. 'If my father hadn't found it after all these years, maybe it didn't exist. It is a fantastic discovery. John is learning the trade and has a great eye for it, it must be in his blood. It is a sizeable deposit and we conservatively estimate that there is enough Blue John stone in this deposit to keep us busy for the next decade at least.