1. Kryptonite
A brief history . . .

2. Kryptonite
The term used to designate any surviving fragment of the exploded planet Krypton, home world of Superman.
Source:

3. Other varieties: Jewel Black Anti- X- Slow Magno Bizarro Red
Kryptonite-X or Kryptisium
Pink
Silver
Source:

4. Kryptonite Introduced in 1943 on the Superman radio series
Allowed the voice actor (Bud Collyer) to have some time off!
Introduced into the comics in 1949

5. Naming Minerals “”Kryptonite” is often assumed to be a mineral
“…different forms of kryptonite may represent multiple allotropes or isotopes of green kryptonite, or a more exotic variation in composition based on currently unknown particles.” -
However . . .

6. Naming Minerals Chemical nominclature
“- ite” suffix = a compound
THEREFORE, is Kryptonite really a mineral?

7. The Real World
Dana’s “Manual of Mineralolgy” is THE source of all things mineral
No entry for “kryptonite”

8. The Real World Mindat.org (URL:http://www.mindat.org/min-6682.html)
Kryptonite
Formula: 'A sodium lithium boron silicate hydroxide with fluorine‘
System: Hexagonal
Color: Green, Red, Gold, White, ...
A rare mineral well-known for its harmful effects on super-heroes.

9. The Real World Mindat.org (URL:http://www.mindat.org/min-31570.html)
Jadarite
Formula: LiNaSiB3O7(OH)
System: Monoclinic, 2/m - Prismatic
It has been widely reported in the media that this mineral has a similar composition to the mythical "Kryptonite" of Superman fame. That claims to be a "sodium lithium boron silicate hydroxide with fluorine", and Jadarite is similar (except it does not contain fluorine). So far the effects of Jadarite on superheroes have not been noted by researchers.
Type Locality:Jadar Valley, Serbia

10. The End!
Or is it?