Rift Iron

A rare metal only found in the rifts near Tenzentak. It appears in veins similar to normal iron, however after it is mined, it grows back slowly. However this regrows produces a toxic off-gas called Rift Smog.

When the iron is refined, forged, and tempered, it posses a unique ability to self repair any damage done to it. A hole in armor reforms in a few days, a wheel on a cart is round again in a week, and a shattered sword can be pieced back together with care. This makes for a very desirable material. It was harvested extensively during the First Age. Its veins would slowly restore themselves, but be quickly remined. This made for little of the resource in the ground, but a slow drip of profit from what was found.

When Iron Light was discovered, the value of Rift Iron skyrocketed. However, its slow regrowth made it difficult to get. On top of that, once Rift Iron is tempered, you cannot change its shape, making any material already used useless for Artificers.

For more lore read Weaving - Desperate People