This Mining leveling guide will show you the fastest way how to level your Legion Mining skill up from 1 to 100.
Learning Legion Mining
You can get the next rank of Mining by simply mining any ore at one of the Broken Isle zones.
In Legion, there are new types of mining nodes, Leystone Seam and Felslate Seam. You can only find these in rivers or caves. I optimized the farming route below for finding these nodes because the basics Leystone Deposit and Felslate are only good until around 30.
1-85 - Suramar
Suramar is a level 45 zone.
Important! You have to find Rich and Seam nodes to reach 85. And at around 70, even the rich nodes are grey, so your only option is the Seam nodes found in caves and rivers.
If no one is farming the ores before you, these 6 caves should always have 1 seam node and one normal node. Mine out every Seam you see, even if it's a grey Leystone Seam, because it can respawn as Felslate Seam the next time you visit the cave. Go inside the cave and walk to the end because you often don't see the ores on your minimap from the entrance!
NOTE: It's important that you follow the route along the rivers because Leystone Seam and Felslate Seam can spawn in rivers!
Coordinates if you have TomTom addon: (type these into the chat)
/way Suramar 40.4, 29.4
/way Suramar 42.2, 29.9 behind the waterfall
/way Suramar 31.5, 26.1
/way Suramar 24.2, 50.7
/way Suramar 28.3, 56.2
/way Suramar 29.3, 50.8
Use this map if you don't have flying.
If you use a flying mount, the respawn rate might be too slow, and you have to wait for respawns, but you can add this other cave.
/way Suramar 19.33, 19.12
85-100 - World Quests
You can level to 95 with Mining ores, but it will be slow because the only node that will give you mining skill is Felslate Seam, which is a rare spawn of Leystone Seam. I recommend stopping at around 85 and do the world quests because some of the World Quests can give you 10 points.
For the last 5 points, everything will be grey, and you can only get skill points by doing Mining World Quests.
Mining World quests show up randomly every 2-3 days, but you will usually get more than one quest. Not all of them will reward you with skill points, but most of them will at least give 1 skill point, and if you are lucky you get one which provides you with 10. (An example would be the "Fiery Leystone Deposits" quest where you have to mine 10 ore to complete the quest, which will give you 10 skill points). The quests will show up randomly, so the time it will take to reach 100 will depend on luck.
Unlocking World Quests
Completing the 
Uniting the Isles quest will unlock world quests. You can get this quest from Archmage Khadgar, but it requires level 45.
Finding Mining World Quests
Mining World Quests are marked with little Mining pick icons on your map.
If you install the World Quest List addon, you can quickly check if there are any Mining world quests up. I highly recommend this addon because it will save you a lot of time, you don't have to check every single zone one by one.
World Quest List Addon
I hope you liked this Legion Mining leveling guide, congratulations on reaching 100!