The crystal cave itself is a spherical mini-cave hidden in the back of a hillside cave six miles from the king's palace at Maridunum. It is described, in young Merlin's first discovery of it, as "a globe, a round chamber floored, roofed, lined with crystals. They were fine as glass, and smooth as glass, but clearer than any glass I had ever seen, brilliant as diamonds."[1] The facets are possibly those of geodes.[2][3]
The hill is considered by the locals to be a home or haunt of a deity named Myrddin, a god of air and heights, so its cave is imbued with magical properties. Merlin lives there whenever not called upon for political duties. The small crystal cave is where he frequently retreats to seek revelations or prophecies.
