Saw Gerrera, Ezra Bridger, and Sabine Wren discover a giant kyber crystal

While kyber crystals are at the core of every lightsaber, the Empire explored ways to weaponize them for more nefarious purposes. They began to mine for kyber crystals across worlds, and were notably thwarted twice in securing massive crystals by the Ghost crew and Saw Gerrera. But on Jedha they uncovered a surplus of kyber, which would be enough to power their dreaded Death Star.