Frystine
Bearing a light blue silvery color, frystine is a type of metal found mainly in the northern mountains of Manniskar (although also being found with some significance in the Under Realm) that has some unique properties to it.
The metal is refined from it's ore counterpart, frystite, and once smelted, it is extremely flexible, durable and resistant, although such properties only exist while the metal is cold, for once it reaches high enough temperatures, it melts and becomes a gooey liquid, akin to quicksilver.
Due to it's incredible strength, it is thoroughly used by both Treria and Thortyr, for military and aesthetic applications. Swords are harder to get dull, naval rams are almost indestructible and energy-absorbent, while rings and necklaces shine brightly under both sun and moonlight. It is also common knowledge that many of the southern nations covet it strongly.