Necronium

Necronium is a magical metal that came to existence when leftover magical energies on battlefields from the Gielinorian God Wars infused nearby pieces of armour. In the Sixth Age, these battlefields were unearthed, allowing smiths to delve the necronium and create armour from it. Doing so requires smithing levels in the 70s, bringing it on par with Barrows armour.

Necronium was announced at RuneFest 2013 by Mod Jack as part of a design to revamp the mining and smithing skills, which means nothing is set in stone yet.

On the Official RuneScape Lore Forum Mod Jack posted the following: