Haven't seen it in this forum, so I gave it
A step-by-step guide:
1. You need to get to lvl 50
2. Do the quest for 2nd job promotion
3. Go to Great Mine in Highlands or (unadvisable at your level) Golden Basin through your faction's territory (get there from Southern Plains village)
4. Put Mining skill in quickslot
5. Cast Mining on pile of Minerals (they are selectable like a mob and their name is "mineral")