Crystal
Clairvoyance, supernatural knowledge, spiritual perfection, chastity. The crystal, a solid that light can penetrate, struck the ancients as celestial and magical. The crystal symbolized the notion of passing or looking beyond the material world, and was both emblem and tool of shamanistic powers. Hence the visionary crystal palaces and magical crystal (or glass) slippers of folklore. In Buddhism the crystal is the insight of the pure mind. From: Dictionary of Symbols (Tresidder)
Songs referenced:
Carbon