I just learned by chance that iron stuff can be melted to ingots with fire, in this case firebolt was shot over a stack of spears which turned into one iron ingot for each spear.
Handy for the non mining proficient smither.
Is there just a small chance for this to happen?

I assume mithril and adamantium is not meltable in similar fashion.

Also had a game where I dug out the entire ogre caves, the ingame time was still not that bad.
Seems like wilderness walking w/o 7 league boots is worse than extensive mining.