Lithomancy? (Stone Magic)

[Aeolius]

I find myself intrigued by bezoars, pearls, mad stones, hagstones, lithomancy, snake stones and the like. Has anything been done with these, in D&D? I may end up making a class (witch specialist?) that makes use of natural items like those above.

 

[Voadam]

Crystalmancy

Mineral Magic

Spell & Magic has a prestige class for gem magic.

Legends of Sorcery Gems

Also some stuff from Bards and Sages for the Karma system.