Kryptonite (small stone) is an imaginary material of the DC universe in which there are many varieties of different colors: green , red , gold , blue , white etc.. They have the property to affect each differently, the superhero Superman . However, only the green varieties, red and gold are really dangerous for him and are his Achilles heel .
In the various stories of Superman ( comics , movies, television series), possession of kryptonite is a major quest of the enemy heroes . The TV series the most recent Smallville , sees most of his plots related to kryptonite and called more frequently in Seasons 1 and 2 "fragment of a meteorite." Moreover, unlike other stories where the kryptonite is very rare (a few kilos on the planet), in Smallville, the region has suffered two heavy rains meteorites in 15 years on earth thus bringing tons of kryptonite find fragments of rock is very common.