what does the "Bonus find" from Treasure hunter actually mean? does it just mean chance for an extra item from mining (2x coal instead of 1 or similar)?

additionally: how hard would it be to get most of the mining bonuses to function on non-drilled resources, like rocks and trees? would be nice to have manual tree chopping early be helpful

The treasure hunter picks randomly between iron, copper, coal and stone and give you an extra item of that kind, so you can technically get copper by mining iron, but it will be rare. I was thinking about including mod-related things or rare materials, but those seemed way to OP and could cause things I cannot predict, like you ending up getting an ore from a random mod that is supposed to be extremely rare.

The regular bonuses and other skills are about double (or more) drops.

About the rocks and trees, this is pretty easy, and I like the idea, so I'll add it to my TODO list. I'll leave you a message here when it's done.

Done! It was a bit trickier than I originally thought. When you actually go into the code, you actually see what a "tree" and "rock" is. Apparently, trees that you plant on Gleba are no trees, but "plants", so those won't count, and I think it's better like that, because mining Gleba plants for 4x output might be a bit unbalanced.

And since we were talking about Treasure Hunter, that also applies to trees now... which makes things quite interesting and kind of allows you to do a no-ores run. Also improved the tooltip a bit to prevent further confusion.

hell yea!!

does that "gleba trees technically plants now" also apply to trees i manually seed once i get the recipe? im assuming so but i have yet to sit down and find out

I'm 99% sure that is the case, since they are treated the same way. I will check and tell you for sure when I get the chance.

Just checked, they are, indeed, "plant", not "tree", so they won't give any exp.