The Old Mine uses the Prospectors and Prospector’s sets to mine for Nickel and Zinc Ore. You will need free Prospector’s (cannot be working)to be able to dig for the new ores. The more you upgrade the Old Mine, the more Prospector’s Sets and time it takes will grow, but you also get more Zinc and Nickel Ore to trade in the Exchange House. You will need to have the Old Mine Upgraded to stage 2 in order to go prospecting inside.
After upgrading to stage 2, you will be able to use 1 Prospector to mine for Zinc and Nickel Ore. It will take 15 minutes to work in the mine. When finished, click the Yellow “Gather Resources” button and receive what was mined. You will receive 2 Zinc and 2 Nickel Ore.
In order to upgrade the Old Mine You cannot have anyone working inside. Click the blue “upgrade building” button to upgrade your Mine. I wouldn’t advise upgrading too quickly. It costs more prospector sets to mine after each upgrade.
Stage 3 of the Mine. Each Prospector will use 2 Prospector Sets, take 30 minutes and gives 4 Zinc and 4 Nickel Ore.
Stage 4 (fully upgraded) You can have a total of 3 Prospector’s working in the Old Mine. It will require 4 Prospector sets for each one. They will work for 1 hour each and you receive 8 Zinc ore and 8 Nickel ore for each one.