Thaumium

Thaumium is a naturally occuring metal that has similar properties to steel, except it is harder and more resistant to stress. Thaumium ore is dark blue, rough and matte. Refined Thaumium is similar in apperance to steel, except it has a slight blue tint. Thaumium is required to create neon weaponry, and the presence of it can enhance most types of Thaumaturgy. It is not especially rare, but exceptionally high demand and a difficult refining process means it is expensive.