From Wikipedia:

To minimise visual impact from the coast the quarry is sited 1 mi (1.6 km) inland, and cut down into the mountain 1,600 ft (500 m) above sea level. Each explosive blast dislodges about 70,000 tons of granite, which is transported by dump truck to the primary crusher, which reduces it to lumps no bigger than nine inches in diameter.[2] It is then transferred by conveyor belt to a heap that covers the “glory hole”, a 1,000 ft (300 m) vertical shaft 10 ft (3 m) in diameter, which is permanently full of rocks. At the base of the glory hole, deep inside the mountain, rocks are transferred to a horizontal conveyor and moved through a 1-mile-long (1.6 km) tunnel to the second crusher on the shore, where oceangoing ships are loaded in the deep-water docks at the rate of 6,000 tons per hour.

In 1998 there were approximately 160 employees either living on site or commuting by boat from Barcaldine, near Oban. Exports at that point were going to Amsterdam, Hamburg, Rostock and Świnoujście, in Poland, as well as the Isle of Grain in the Thames Estuary.

Reserves of granite are estimated to last at least until the year 2100, when the excavation will have created a new corrie 1+1⁄2 mi (2.4 km) square and 400 ft (120 m) deep.

From Wikipedia:

In 1976 the UK Government commissioned Sir Ralph Verney to analyse the shortage of aggregates for building. The resulting “Verney report” led John Yeoman, Chairman of Foster Yeoman, to the idea of a super-quarry situated in a remote location from which stone could be exported by sea. To this end in 1982 he bought the 2,400-hectare (5,900-acre) Glensanda estate in Argyll from Mrs Patricia Strutt who also owned the Kingairloch estate which she also sold to Foster Yeoman in 1989.Glensanda went into operation in 1986 when the first shipload of granite left for Houston, Texas, USA. In June 1989, extractions began using the “glory hole” and conveyor belt method.

Working Quarry