Why wouldn't mining the elemental plane of earth be effective, well its all in how you look at the planes.
First the elemental plane of earth is mostly dirt and rock, with little precious ore in it.
Now just by third edition there are hazards that need to be considered even if you do find ore. Earth Elementals and Xorns attacking those invading their homes (and even if you can kill them, your miners likely can't.) Dao slavers (Motp) seeing an oppurtinity to aquire a few slaves for their mines, and other nasty natives of the plane.
Then theres other consideration, where are you going to take all the dirt and rock you need to dig through to find ore veins. The plane is almost entirely solid so you would need to take it out through the portal, attracting attention of your enemys. (Say your a villian, and your spys told about massive piles of dirt near your enemies abode and there was no apperanent digging. You would investigate wouldn't you.)
Now if that isn't enougth to make it to costly, I haven't even began to dive into all the fun stuff in the planescape guide to the inner planes. If you go add a few features from that book, which was the most detailed guide to the inner planes in the history of D&D theirs other problems to worry about, like passages just slowely close over the course of 3 days, as the plane heals itself, so you have to do a lot of matincence to keep up a mine.
Another feature from the guide to the inner planes, sometimes creatures to powerful to kill are locked in the plane by a prison of solid stone. But what if during the mining you just happened to break the prison enought for the creature to escape.
One last disasterous feature that could go wrong is the plane of earth experinces earthquakes sometimes, caving in passages and inflicting damage.
That should be enougth to stop all but the most powerful organization from mining. If that isn't I still have more troublesplanescape made for travellers and miners on the plane of earth.
First the elemental plane of earth is mostly dirt and rock, with little precious ore in it.
Now just by third edition there are hazards that need to be considered even if you do find ore. Earth Elementals and Xorns attacking those invading their homes (and even if you can kill them, your miners likely can't.) Dao slavers (Motp) seeing an oppurtinity to aquire a few slaves for their mines, and other nasty natives of the plane.
Then theres other consideration, where are you going to take all the dirt and rock you need to dig through to find ore veins. The plane is almost entirely solid so you would need to take it out through the portal, attracting attention of your enemys. (Say your a villian, and your spys told about massive piles of dirt near your enemies abode and there was no apperanent digging. You would investigate wouldn't you.)
Now if that isn't enougth to make it to costly, I haven't even began to dive into all the fun stuff in the planescape guide to the inner planes. If you go add a few features from that book, which was the most detailed guide to the inner planes in the history of D&D theirs other problems to worry about, like passages just slowely close over the course of 3 days, as the plane heals itself, so you have to do a lot of matincence to keep up a mine.
Another feature from the guide to the inner planes, sometimes creatures to powerful to kill are locked in the plane by a prison of solid stone. But what if during the mining you just happened to break the prison enought for the creature to escape.
One last disasterous feature that could go wrong is the plane of earth experinces earthquakes sometimes, caving in passages and inflicting damage.
That should be enougth to stop all but the most powerful organization from mining. If that isn't I still have more troublesplanescape made for travellers and miners on the plane of earth.
