Vis

Vis is a mineral that came to Earth when the Great Meteors fell in 2378 - Old World time. Vis can come in many forms, such as crystals, stones, and orbs, but the most common is the Vis pearl.

After the world is destroyed by Vis, the world won't discover Vis again until year 175 by Emperor Regius I, marking the end of the Age of Unification (150-175) and the beginning of the Age of Vis (175-225) and it isn't until 177 when it is discovered that Vis can be used as an unlimited resource of power. The Old World did not see Vis as a power source until July 6th, 2378 - Old World time. This is mentioned in the short story -200 The Meteor and the Miracle Stones.