The Blue Mountain Quarry is located near the bottom of Shane Dooiney mountain on the Skarloey Railway. Merrick and Owen are based here. The Skarloey Railway engines often work at the quarry transporting and delivering the slate and stone to wherever it is needed around the island. The company owns many other vehicles that also assist with the workload. Many standard gauge engines have been known to work here, most frequently, Paxton, who carries the stone and slate along the standard gauge lines, where the smaller engines are unable to travel. Blondin Bridge is also located here.
Since the seventeenth season, the narrow gauge line to the quarry became dual gauge to accommodate the standard gauge engines. For standard gauge engines to access the Blue Mountain Quarry, they have to switch near Whiff's Waste Dump onto the Quarry Branch Line.
The company's logo consists of an incline with a truck on the ramp, the mountainous landscape as a backdrop, and the acronym of BMQ (Blue Mountain Quarry) situated at the bottom of the logo. All of the quarry vehicles acquire this logo on their liveries.