Iona Marble Quarry is an interesting former industrial site at Port Carnan a' Ghille on the southeast coast of the island, situated 2 miles (3 km) southwest of Baile Mor. The distinctive green and white coloured ornamental marble was extracted here from Mediaeval times. It had been used in Iona Abbey and pebbles were also sold to tourists by the local children the early 18th C. Around 1790, John Campbell, 5th Duke of Argyll (1723 - 1806), in partnership with industrialist William Cadell (1737 - 1819) and Swiss geologist Rudolf Raspe, set up the Argyll Quarry Company intended to extract the stone and ship it from the island on an industrial scale, but the enterprise failed. The quarry reopened again in 1907 but closed for the last time c.1915.
The quarry exploits a 20-m (65-foot) wide band of Iona marble, which is a metamorphosed limestone of late Pre-Cambrian age (dated to 1418 million years) lying within the upper units the Lewis Gneiss which covers much of the island. The quarry lies in a steep little ravine representing material which has been removed. It still contains the remains of rubble-built buildings and machinery from the last phase of operation, including a stone saw, gas engine, gas producer, countershaft, derrick crane, rail trolleys, together with waste heaps. A store for the gunpowder was built a short distance away from the quarry for safety. The National Trust for Scotland has painted some of the machinery black as a means of preservation.
The site has been a Scheduled Monument since 1992 in terms of its national importance as industrial archaeology.
