So, here is an idea to update gold mining and make it rewarding.
Multiply the gold in each tile by 100 - so lvl 1 Gold Fields have 1,000 etc. Same for Gold of the Gods so lvl 6 would be 100,000 gold.
Increase gold mining speed to about 1/4 of Silver.
Add the uber only gems as the rewards if you clear a tile. I'm not talking about big generosity here but if I could get 1 simple Aquamarine or Euclase or other uber only gem every time I took out a lvl 1 Gold Field I'd be way more interested. You could make it 2 for a lvl 2, 3 for lvl 3, 1 usual for lvl 4, 2 usual for lvl 5, 3 usual for lvl 6. Then do the same for Gold of the Gods but with Unusual and Rare uber only gems.