Perhaps crystals and stones are especially apt symbols of the Self because of the “just-so-ness” of their nature.
Many people cannot refrain from picking up stones of a slightly unusual color or shape and keeping them, without knowing why they do this.
It is as if the stones held a living mystery that fascinates them.
Men have collected stones since the beginning of time and have apparently assumed that certain ones were the containers of the life-force with all its mystery.
The ancient Germans, for instance, believed that the spirits of the dead continued to live in their tombstones.
The custom of placing stones on graves may spring partly from the symbolic idea that something eternal of the dead person remains, which can be most ﬁttingly represented by a stone, for while the human being is as diﬀerent as possible from a stone, yet man’s innermost center is in a strange and special way akin to it (perhaps because the stone symbolizes mere existence at the farthest remove from the emotions, feelings, fantasies, and discursive thinking of ego-consciousness.
In this sense the stone symbolizes what is perhaps the simplest and deepest experience —the experience of something eternal that man can have in those moments when he feels immortal and unalterable. Carl Jung, Man and His Symbols, Page 206