This type of faery can be found all over Europe as well as in countries settled by European peoples, such as the United States. Called Coblynau in Wales, Kobolds or Wichtlein in Germany, Knockers in England and Tommy-Knockers in the USA. They are found in any mine being worked by humans and can be either helpful or harmful.
Mine faeries are always seen as male and can appear in size anywhere from two to six feet tall. They are generally described as small wizened men with beards and either blue or red hats. Mine faeries usually dress to mimic the miners who are working near them so their appearance changes slightly with the times, but they are always seen carrying miniature pick axes and other mining tools. They tend to be very secretive and are easily upset if they catch anyone looking at them so it is more common to see than hear this type of faery if you work in a mine.
There are stories of helpful Knockers who would rap or “knock” on the walls of a mine shaft to indicate the locations of ore deposits, which is one possible origin of their name. In England they are known on occasion to warn miners of impending disasters such as cave-ins by creating weird noises to get the miners out of the dangerous area. In other cases, if they favored a particular miner they would wait until he was alone and then appear next to him, working alongside so that he could accomplish far more work than any other man alone could. Many times in such tales his jealous coworkers would eventually sneak back after him to find the source of his productivity only to be spotted by the knockers who would react violently. In one such story from the U.S. the enraged Knockers turned on their human friend believing he had betrayed their secret, and caused the entire mine to explode in flames.
In the case of the Coblynau they are viewed as more of a nuisance than anything else, being known to confuse miners with repeated knockings on the walls of the mine as well as appearing to miners. Those who were not frightened away at seeing the faeries noted that despite looking as if they were working frantically, nothing was ever accomplished. Mine faeries can also be very mischievous, playing pranks on the miners by hiding equipment and leading men astray in the tunnels.
At their worst mine faeries can be deadly. Coblynau when insulted are known to start rock slides and all forms of mine faeries are said to start fires in the mines when angered. In Germany Kobolds are considered malicious being fond of cruel jokes and tormenting miners. The Wichtlein is an omen of death which will be seen or heard knocking three times shortly before the doomed person meets their fate. There is no way to banish or remove mine faeries, if they are present they can only be treated with respect in the hopes of avoiding disaster.
- excerpt from A Child's Eye View of the Fairy Faith http://www.amazon.com/Childs-Eye-View-Fairy-Faith/dp/1300294132