Frigidite

-a type of gemstone which grows best on Voltheim, where it is native to. It radiates cold and can be used for a number of purposes when mined, primarily refrigeration. With enough of them, the weather can be locally changed which can be used for nefarious purposes. It is very rare as contact with Voltheim is not common and it is of little use up there, and was only discovered when brought by the Dvur - Ice Dwarves who migrated to Frostreach.