Hey! First time posting, so hoping to contribute with something good!
I found this bug while leveling mining 475-525 in Uldum. It's an Elementium vein that is placed just by the border between Schnottz's Landing and "regular" Uldum, on the Schnottz side. If you haven't done the quests in Schnottz (not sure exactly which ones though) the vein will disappear a second or two after you cross the border into Schnottz. If you stand just on the edge on Uldum side and go in real fast and start mingin the vein before it disappears you will get the skill, despite the vein disappearing. You will get no ores, but you can go out to Uldum and go back in and mine the vein directly again, since it will reappear once you get out.
Note that the vein might not be there at all times, since someone who isn't phased could've mined it.
You see the vein when in Uldum.
Location of vein (coords 18,56)
Mining the vein while it's disappearing.
Hope it works on most servers! Remember, it won't work if you have done the quests in Schnottz