Jet is fossilized wood. It will become electrically charged when rubbed. Due to its mysterious nature and electrical properties, jet has long been considered a magical "stone". It is said when continuously worn on the body, it is thought to absorb part of the wearer's "soul". Because it is receptive, it absorbs negativity. This makes it protective. To ward off nightmares place in the underside of the pillowcase or have next to the bed.
There is much lore on this interesting fossil. Read more about it in Crystal, Gem and Metal Magic by Scott Cunningham.
Great pieces of jet to scribe into a talisman. Each piece is unique in size and shape.