At the beginning tap the place randomly but make sure you tap the next hole far from the previous one (unless you get “close” or “very close”).
Close means that the rune located 2 squares away from that spot.
Very close means that the rune only located 1 square away from that spot.
You can’t gather more runes if you already reach the maximum runes number (number of required runes to expand). Make sure you expand first before mining because you need to wait for a long time to get the bomb.
The chart is still not complete at this moment!! It will be updated as I progress further.