Middleton Mine is located 4 miles south-west of Matlock and worked the Hopton-Wood Limestone underneath Middleton Moor. At the end of the 1950s the high purity Hopton-wood beds had become too deep to work from an open quarry and adit access was driven to continue extraction underground. By 1993 around 16 million tonnes of limestone had been extracted using room and pillar methods with the later rooms 13m wide and pillars 17m square. There are around 26 miles of tunnels. The mine closed in 2005 but the sealed entrances remain visible. This one is the ventilation drift in the Hopton Quarry side of the operation.