How Do the Basic Metals on Scadrial Replenish?

[dstokes7]

We know that a mechanism was established via the Pits of Hathsin for Atium that was burned to be reconstituted, thus ensuring a constant supply of Atium for all time (ignoring the destruction of the Pits and the fact that Ruin is no more). But what about the other metals? Is there a mechanism for replacing those? Granted, Allomancy doesn't use up all that much metal, but metal reserves on a planet aren't infinite, and eventually Allomancers would burn up all the iron, tin, copper, etc. on the whole planet.

If there is no replenishment, can Scadrians burn metals imported from off-world, or does Allomancy only work on metal specifically tied to Harmony (and therefore Scadrial)?

[alder24]

Yes, metals will eventually reform physically in the same way Atium does, however there is a lot, a lot of metal in the planet's crust so they won't run out of it even if they were trying to.

Spoiler

Brandon Sanderson (paraphrased)

Burned metals are turned into a different form, and will eventually return to the planet. The Pits of Hathsin are meant to foreshadow this.

Phoenix Comicon 2013 (May 24, 2013)

 

[Treamayne]

54 minutes ago, dstokes7 said:

We know that a mechanism was established via the Pits of Hathsin for Atium that was burned to be reconstituted, thus ensuring a constant supply of Atium for all time (ignoring the destruction of the Pits and the fact that Ruin is no more). But what about the other metals? Is there a mechanism for replacing those? Granted, Allomancy doesn't use up all that much metal, but metal reserves on a planet aren't infinite, and eventually Allomancers would burn up all the iron, tin, copper, etc. on the whole planet.

If there is no replenishment, can Scadrians burn metals imported from off-world, or does Allomancy only work on metal specifically tied to Harmony (and therefore Scadrial)?

We have one WoB on this topic, but it's not conclusive:

Spoiler

Questioner

Metal in the Mistborn world, is it renewable somehow? Because when you burn it, it just goes away and then it's converted somehow into energy. Can they run out?

Brandon Sanderson

The way that atium gets back into the system is a bit of a hint... Atium grows out of crystals, and that is being distilled. Let's just say... Investiture is changing into matter as atium is being made.

Skyward Seattle signing (Nov. 10, 2018)

He only specifically mentions the Atium Cycle - but Brandon implies that all metals Burned Allomantically are returned to Scadrial by Investiture reforming the metal in the planet. 

Hope that helps