Kryptonian crystal

Kryptonian crystals are a type of crystalline substance found on the planet Krypton prior to her destruction.

By definition, such crystals would thus be considered a type of Kryptonite, since they are part of Krypton.

In the comics
Kryptonian crystals serve a huge role for Kryptonians. They are used as advanced technological devices which serve a variety of purposes, such as recording videos, and even storing the memories of someone, and they can be projected as a hologram. In the film Superman Returns, Lex Luthor used Kryptonian crystals to grow a new continent.