Coal is needed for stone blocks - upgrades, buildings, storage expansion and for torchs - adventures and land expansion, yet coal is very very rare.
I have two mines, neither gives much or any coal! I went both collections today getting zero coal from either.
That leaves hacking rocks. 20 energy, 1700 coins and seems to produce 3 to 4 coal per rock. That is one torch or two bricks. My problem has become I am almost maxed on stone blocks and stone. This feels so futile spending every spare energy to try to get a drop that should be so much more common, and not being able to store the by product stone because I cant get enough coal to Keep up with storage.
Please make coal a common drop.