Keightley, Thomas - Coal and gold
Type of Spiritual Experience
One allegory that appears to have kept its ancient roots is the idea that ‘gold’ is hidden in the rocks or in coal or similar. In other words, spiritual gold – spiritual experience of a high order - is to be found 'trapped' in darkness. There is a double meaning being used here, however, because coal is also symbolically trapped fire, so we have a literal interpretation – miners of coal had spiritual experience and a symbolic one.
A description of the experience
Thomas Keightley - The World Guide to Gnomes, Fairies, Elves, and Other Little People
Coals are the usual form in which dwarfs conceal precious metals. The trait occurs in Scandinavia, Jutland, Switzerland and many other countries