Excellent concept. however i think there should be some use to the boom town population IE hiring on truck drivers for npc gatherers to gather your minerals or something, perhaps an option to put some mines on a gold spot for a slower residual gold, also employing population.
Biggest complaints: Too often do the gold deposits near the edges of the screen shoot large chunks of gold ore, items, gems, etc, off the edges of the screen. By the time i had all my upgrades maxed out and had purchased the second lot, I had nothing to do but mine gold and wait for the new town buildings to unlock.
Personal two cents: i think it's a good basis for an excellent game, but instead of collecting the gold from the blasts, i think the blasts should open up the ground so you can build mines. And the mines producing ore to be picked up and dropped off at the depots. Of course that would alter the gameplay dramatically and it of course isn't the original intended vision of your game. then again, that's why this portion is labled "personal two cents", as it's just my own opinion.