Elementite is required in order to use Architek in Final Fantasy Crystal Chronicles: My Life as a King. It is found in the many dungeons surrounding Padarak. Since the king cannot go in search of elementite himself, commissioned adventurers bring it back when they explore the dungeons or defeat an enemy. Certain bosses also give elementite rewards when defeated. The Elementite Gauge reflects on the current stock.
The only other way of getting elementite comes at the beginning of the game during the chase of Pavlov.