This is simply an idea for the devs to consider, although I think they may have thought of this already.
What about random mining nodes? Maybe not instead of the nodes we have now, but maybe make an area where the mining nodes don't always respawn the same type of rock. You can limit it to a few types... Maybe a dull/beryl node or a beryl/sparkly node. It might help level the mining field and keep things exciting while forwarding your intention of not having any "this is the best way so it's the only way" overpowered places. By the same token, maybe introduce a rarer rock type that only spawns randomly but has a higher percentage of gem drops or something.
While I like knowing where the rocks are, I think this would bring a nice sense of excitement to an area of the game that feels a little stagnant.