A fast question, since I couldn't find an answer while diggin' in Google.

 

Any ideas what are the exp rates of mining in dg/c3 if you dont go for the boss and just go around mining rocks ? (96 mining I have prometium pickaxe)

 

(I want to combine fishing, woodcutting and mining training in one and I want to see if it's worth to add the mining part to it)

I don't have an exact number on it, but it is awful XP. It was tested a couple of years back and it's really not worth doing at all. It's best to just stick with c2 for WC and Fish and do Seren stones/LRC/Warbands for mining.