At frisians every miner which is better gets goldmine symbol and at coalmine it is also at a normal miner.
I don't understand fully what is the problem. What I could confirm is that the menu.png for most frisian workers isn't very nice, as the ware symbol (e.g. iron ore for normal miners and gold ore for master miners) is drawn over the worker symbol in such a size that it most times is completely hiding the worker.
What I can't confirm that the icons are mixed in the mines. Could you provide a screenshot of the situation?