Aarnivalkea

The Aarnivalkea are spots where an eternal flame associated with Will o' the wisps burns in Finnish mythology. They are claimed to mark the places where faerie gold is buried. The are protected by a glamour that would prevent anyone finding them by pure chance, but if one finds a fern seed from a mythical flowering fern, the magical properties of that seed will in addition to providing one with a glamour of invisibility, also lead the fortunate person to these treasures. Since in reality the fern produces no flower, but reproduces by spores under the leaves the myth specifies that it blooms only extremely rarely.

Although clearly folklore, the claim has been made, that Outokumpu coppermine; the largest coppermine in Europe at its times; with 100 kilometers of tunnels beneath the ground was discovered due to some light phenomena or another.Fact|date=February 2007