Stalhrim is a primordial substance older than metal. Stalhrim is just the name mortals have given it, as its original and true name predates most languages and cannot be properly enunciated.
In some cases, this substance is present within the bodies of Elementals and Atronachs and bears a form of magical essence entirely separate from magical enchantment giving weapons and armor made with it a near-magical quality without any practices or ritual performed to grant such qualities. Part of a collection of similar materials, Stalhrim has also been called "Enchanted Ice." As such, there are other materials with obscure and mortal names that had older names in the past, that are in actuality "Enchanted Fire," "Enchanted Earth," and "Enchanted Wind."