The Emerald Tear

During an Impetus event, energy rips through the world at the Emerald Expanse (formerly known as the "Eternal Expanse"), forming a Tear that reaches deep into the earth. 

The sands of the Emerlad Expanse turn into a shade of green and the immediate area around the tear becomes a fortress of green glass, which later is discovered to have magical properties.

The "Emerald Glass" becomes a much desired resource and wars are fought to this day over the region to secure the supply. Artisans solely specialized in the production and refinement of Emerald Glass become a desired profession. It requires extraordinary skill to process this material. While glass made out of the sands of the Emerald Expanse also holds some magical properties, the glass that naturally formed at the tear has the purest and most potent magical energy. 

The region seems to have a close connection to the Plane of Earth.