Blue Mountain Quarry is a quarry that made its first appearance in Blue Mountain Mystery. Merrick and Owen are based here. Skarloey, Rheneas, Peter Sam, Sir Handel, Rusty, Luke, Paxton (as well as Thomas and Toby on some occasions), and many other vehicles work here. Blondin Bridge is also located at this quarry.
It has replaced the Skarloey Railway Slate Quarry.