Terelian ore

Terelian ore, also known as Terilian ore, was a very dense, valuable ore that at one point was mined on an asteroid in the Trebodar system. The ore was refined at a facility on the asteroid, after which special large ore transport starships picked it up at the mine's docking bay.

At some point, the asteroid mine was abandoned, with a group of Galderian enslavers setting up a base there by the time of the Galactic Civil War between the Galactic Empire and the Rebel Alliance. By that time, multiple fist-sized balls of Terelian ore—which in a specific market could be sold for up to fifty thousand credits—had been sealed in the mine's vault room, with the Galderians being convinced that the room contained something highly valuable yet not being able to breach its door through the use of heavy blasters.

Text and facts from the “Terelian ore” article on Wookieepedia, licensed under CC BY-SA 3.0. Modified for this site.