Inspired by this topic: viewtopic.php?f=48&t=61639
Which references this method of primitive iron acquisition: https://en.wikipedia.org/wiki/Bog_iron
The main problem: it's super hard to start mining, and a way to get surface level metal would be nice especially for less experienced players. To balance this suggestion with the current metal progression system, I wanted to keep the idea simple and propose the following:
1. You can smelt Rustroot at a stack furnace into Bog Iron Nuggets with a 30% chance. Bog iron, as an early, impure metal, counts as a SOFT metal and so would be on the same level as tin and lead, the level 1 ores.
*Include this in the description of Rustroot so players know they can smelt it.
*30% chance is so, on average, you get enough for 1 bog iron bar every 2 batches of rustroot in the furnace (which is 36 units of rustroot so it seems fair to me).
2. Change "More irrlights when smithing" Blacksmith Credo Reward #2 for "Chance to obtain cast iron nuggets from Rustroot in Smelters". This could be more contentious because of infinite forageable iron, but it could make for a new interesting use for Rustroot in the later stages of the world (and since you only get nuggets, it would still be super work intensive).