I used to play World of Warcraft and a few other MMOs for their crafting systems and always wondered what a fantasy RPG with a crafting system would look like with a more realistic distribution of resources. I'm tinkering with an RPG framework to make a sandbox to test out my ideas for my dream crafting system and figured this would be a good chance to experiment with realistic resource distribution on the map as well.
I'm not going to tackle all of this in a single question and just going to take it on pieces at a time, starting with caves. I remember caves being a good place to go for ore nodes in WoW, after all.
So, I wanted to ask a pretty simple question. How realistic is it to find ore veins inside of natural caves? Would only certain minerals be found in caves? And which types would appear? Would it be more common to find caves with ore or without?