Labruntine

A material mostly unknown to mankind in the present days, as it can no longer be found anywhere in the surface or in ordinary mines.
Labruntine is a dark coloured metal gives away hues or purple and violet, known for being indestructible, immune to most magical phenomena, if not all, and resistant to any weather conditions or the wearing of time.  The only known records of the existence of this rare material is in the legendary doors that guard the entrances to the Under Realm, as it is not just a means of keeping the darkness trapped in there, but also to stop curious explorers from visiting The World Beneath.
A known entrance, written in the book On Otherworldly Things, by Auguste Degas, lies beneath the White Palace of Umera, and uncountable attempts have been made by maesters and scholars to study the fabled, black-purplish metal, in which the only conclusion so far achieved is that it is invulnerable to everything and it's forging, a mystery "beyond the capabilities of mankind".

Type

Metamaterial

Rarity

Only found in the Under Realm

Color

Black-Purplish

Boiling / Condensation Point

Unknown

Melting / Freezing Point

Unknown