Royal Mines Act 1424

Of mynis of golde and silver

Item gif ony myne of golde or siluer be fundyn in ony lordis landis of the realme and it may be prowyt that thre halfpennys of siluer may be fynit owt of the punde of leide The lordis of parliament consentis that sik myne be the kingis as is vsuale in vthir realmys

Source

 * The text of the Act from the Statute Law Database (accessed: 17th February 2008)