The Chu-Gon Dar cube was a very special item, capable of transmogrification. It was made by Jedi Master Chu-Gon Dar thousands of years before the Clone Wars. This item was only compatible with objects with a special Force aura. These objects, after several volcanic eruptions, rose from the old Jedi Temples, and lay scattered on Mustafar.
Behind the scenes
The Chu-Gon Dar cube was an item in Trials of Obi-Wan, the third expansion for Sony Online Entertainment's MMORPG Star Wars Galaxies prior to its closure on December 15, 2011. It was a reward for a short quest for the NPC Ithes Olok.
Many "glowing" items could be looted from killed enemies all over Mustafar. Putting various combinations of these items into the cube produced new items such as Mustafarian furniture, buffs, weapons, armor and other useful items.
An entry in Sony Online Entertainment's Knowledge Base that was published shortly before the release of Trials of Obi-Wan to inform players about the new features called these items "The Cubes of Jen'ha Tar".