Mulberry Downs Quarry is a disused opencast tin mine in Cornwall, England, UK. Today the site is described as a 'chasm' being a steep or sheer-sided pit 700 foot (210 m) long and up to 100 foot (30 m) deep, and the quarry and immediate surroundings are heavily wooded. The quarry was designated as a Site of Special Scientific Interest (SSSI) in 1973 for its geological interest.