[2021] Ore Gen map or info?

You say 'not asking about surface nodes', but, Tbh, I haven't found an ore vein underground that wasn't telegraphed by a surface node. Dig directly under surface nodes and you find an ore node- EAch node is comprised of 2-4 different kinds of ore, of which one of them is guaranteed to be the same kind as the rock on the surface. These nodes then can extend just a few blocks down, or all the way to bedrock.

You can of course just dig around at random a la minecraft, but, you'll basically just be finding veins that are marked by a surface node. I guess given that most/all nodes begin from the surface, that being near the surface is the best place to tunnel around? Kinda?

If you really want to, ahem, dig deep into this, it’s all laid out in Config/biomes.xml.