Thread:DaPowerofDaMind/@comment-12184437-20130801032713/@comment-6829135-20130803083529

Rocks too, but crystals are refined, and metals also affect stuff. Each crystal has different properties, so you can't use something completely different to improve psychic abilities. Most plants have psychic properties as well, but crystals are easier to keep and don't rot. Amethyst is a good psychic crystal.