Is there any benefit to getting quarries?
Solution 1:
The quarry has two effects: improving the mineral production and produce a bit of coal. Other then that, it doesn't do anything. But I found that coal was a resource I was lacking during midgame, so that's why I built quite a lot of them myself. So the mineral boost is not that necessary, but the little bit of coal is.
From the source code:
effects: {
"mineralsRatio": 0.35,
"coalPerTickBase": 0.015
}