A subterranean, gnomelike spirit, supposed in Wales and Cornwall in former times to have by their sounds denoted the whereabouts of minerals and rich lodes. They have been described as little statured, and about half a yard long. The Cornish spirits were thought to be the ghosts of Jewish miners who worked the mines in the eleventh and twelfth centuries.
Knockers were generally regarded to be harmless and, out of sight of humans, could not endure the sign of the cross.
In Germanic folklore, there were two species of mine-dwelling spirits, one fierce and malevolent, the other gentle and benevolent, appearing like little old men dressed as miners, and not much above two feet high.
"In the Cardigan mines, the knockers are still heard, indicating where a rich load may be expected." - Chambers' Journal, I, 371-2 (1885).
- Hazlitt, W. Carew. (1905). Faith and Folklore. 2 vols. London: Reeves and Turner, p. 2:358.
- MacKillop, James. (2004). Dictionary of Celtic Mythology. New York: Oxford University Press, Inc.