It's really unbalanced and I think It should be changed, amount of gold ore. Amount of gold ore = 300, it mean, 300 gold ore = 150 gold,
150 gold = 37 coin. Ressorses for building 1 gold mine 1400 hardwood planks, 1400 marble, 1500 tools. All this ressorses have trade value cca 400 = 25 coin, so it mean if you don't build gold mine and just sell ressorses you need to build 1 gold mine you will earn about 270 coin. So when people finally understand this calculation that you get 270 coin instead 37 noone will build gold mine anymore, offc you can buy some gold deposit, but diamonds needed for that again are not worthfull to spear on it. So finally you come to conclution gold mine is usless building in this game. My sugestion would be gold ore must be by deffalt atleast 2000+, 2000 mean you can get 250 coin from 1 gold mine.