Generally, crystals formed when they underwent a process of solidification. Under ideal conditions, the result might have been a single crystal, where all of the atoms in the solid fit into the same crystal structure. However, many crystals generally formed simultaneously during solidification, leading to a polycrystalline solid. Most metals encountered were polycrystals. Crystals were often symmetrically intergrown to form crystal twins.
Many types of crystals were known to exist. Examples include memory crystals, such as the Kyber memory crystal used by the Jedi Order to locate Force-sensitive children, and lightsaber crystals used by the Jedi and Sith in the construction of lightsabers. Lightsaber crystals focused a blade's energy, augmented its properties and, in the case of crystals like the Kaiburr crystal, could greatly enhance the weapon's power. Crystals could be found on worlds such as Ilum and Dantooine.
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