Kryptonite (object)

Kryptonite rocks are fragments of Superman's homeworld, Krypton, which exploded long ago. The emerald-coloured jewel produces a weakening effect in Kryptonians. Long-term exposure to the rock can be fatal. In addition to green kryptonite, the ore has been discovered in a variety of forms, all of which produce different negative effect s in Kryptonians. Additional colours include: red, gold, black, and rainbow.