Cliff-Marble was a building material taken from the Cliff-Quarries of the Edgelands which was used to decorate buildings in the First Age of Flight by the First Scholars during the early days of Sanctaphrax. It was prized for its texture and its luminous glow. It was used by the School of Light and Darkness, the College of Rain, the Knights Academy, and the College of Cloud.
The Academy of Wind, on the orders of their High Professor, Aurelius Ventilix, was intent upon outdoing the other schools. Under Ventilix's command, the school managed to secure a monopoly on Cliff-Marble by organizing what was to become the first of the Leagues of Undertown. It then proceeded to cover the entire surface of its institution with Cliff-Marble, transforming it into the most glamorous facility in Sanctaphrax.
Soon, however, the academics discovered that the excessive use of Cliff-Marble came at a heavy price. The material began to attract Glisters, which appeared in droves wherever the material was used and manipulated the emotions of the academics. The Glister infestation grew so severe in the Academy of Wind that its scholars were driven mad, and slaughtered each other during the Academy of Wind Massacre. In a panic, the other schools of Sanctaphrax had all Cliff-Marble removed from their buildings, except for the Knights Academy, which kept its West Wall decorated with the material -- this was allegedly done to discourage nosy academics from spying on the school.