Alum is a valuable chemical compound, used for many purposes across the Westlands. The largest alum deposits in the known world come from Ghealdan, and the trade levies and taxes on alum by itself have supported the Ghealdanin throne for generations. Tear and Arafel also have significant deposits which bring significant revenue to those countries.
In 1000 NE large alum deposits were discovered in the vicinity of Danabar, an estate belonging to Elayne Trakand. These deposits were used to guarantee bank loans which helped fund Elayne's claim to the Lion Throne.
The name of the compound is in reference to real world potassium alum which is used in a variety of disciplines from medicine to water treatment.