Hello there!
First of all, I'd like to say it doesn't seem intended but probably deserves to be in guides section.
So this trick helps you level your mining skill at an insane rate, here's how:
1. Wait until the Massive Leystone world quest becomes available. (Massive Leystone Deposits - Quest - World of Warcraft)
I had two of them up: the first one in Stormheim and the second one in Highmountain. Highmountain works the best because the area is easier to navigate.
2. Disable autoloot and mine all the nodes you see (DON'T LOOT THE NODE so you don't gain credit for the world quest). each node you mine will grant you a skill point (up to around 750 skill level) The ores will be sent to you via mail.
3. Realmhop to a different realm and repeat.
Using this method I went from 550 to 750 skill level in an hour.
Please notice that you might hop to the realm you already visited, just mine one node to see if it gives you a skill point and if it doesn't simply hop to another realm.