A stone reputed to cure diseases in the joints. It is said by Thomas Pennant to have been made from gryphite — the shell of the genus Gryphaea (an extinct oyster, also known as Devil's toenails). The name comes from Gaelic crùban (squat, crouch) because the disease in the feet caused man and beast to crouch, unable to stand.
A Cruban Stone at Breadalbane was lent only under the pledge of two cows (an geall càraid cruidh). If the stone was not returned the cows were to be forfeited.
- Campbell, J.G. (1902). Witchcraft & Second Sight in the Highlands & Islands of Scotland. Glascow: James MacLehose and Sons, pp. 92-93.