Our marble cabochons are sourced from the Scottish Highlands and the island of Iona. Iona marble is a 2700 million year old combination of white marble streaked with yellow-green serpentine, known by some as the sacred stone of Columba. The marble quarry closed in 1918 but this material is gathered from underwater seams on the southwest of the island. Hardness 3-6 (Mohs).