deep core mining

Some ore types have to be mined through high pressure chemicals that are pushed into the ground to wash out the ore that you want. It would be nice to have a building that has to be supplied with these chemicals, power and with workers. You will get dirty ore that needs to be refined before it can be used to smelt it in a blast furnace or arc furnace.

I've heard of extracting copper and uranium this way. I'm not sure if it's safe and effective to do this on a tiny Island, though. Especially if you really on the water table.