The Chaos Crystal is a dark side gem that contains lots and lots of deadly Sith Magic. If someone controls it like Darth Grievous the Crystal will grant the owner many dark abilities such as making a Star go Supernova. The only way to counter the power of the chaos crystal is the Matrix of Leadership which can light the most darkest hour. Before anyone own the Crystal the Crystal was hidden in a Room in the Lair of General Grievous. After the rebirth of Grievous the Crystal came into Grievous's hand and used it to build up a sizable army to take over the universe. Darth Grievous was also the host for the Chaos Chrystal and absorbed the dark energies from the chrystal. In the end the Chaos Crystal is destroyed by the Matrix of Leadership.
The Chaos Crystal is similar to the Chaos Heart from Super Paper Mario.