Exotic elements are a division of resources.
Exotic elements are one of the eight divisions of the resources in No Man's Sky.
Exotic elements are mainly used as an ingredient for refining other resources or tradeables. They are the main ingredients for crafting freighter related base building products and some planet/moon base building products.
Tritium can only be mined from asteroids by using a starship weapon or by colliding with an asteroid.
The others can be found: