I optimized the farming route below for finding these nodes because the basics Leystone Deposit and Felslate are only good until around 30. You can only find these in rivers or caves.
In Legion, there are new types of mining nodes, Leystone Seam and Felslate Seam. You can get the next rank of Mining by simply mining any ore at one of the Broken Isle zones. And if you are low on gold, I recommend trying this Gold Making Guide, it can help you to make a lot of gold. You’ll never have to switch back to a website, or even the in-game main map to see where you have to go or what’s next. All the detail that you need to complete the quests are included. The guide is in a small window on your main screen in-game. I recommend using Zygor's 1-60 Leveling Guide if you are still leveling your character or you just started a new alt. Mining serves three professions: Blacksmithing, Engineering, and Jewelcrafting, so it's really good combined with any of these. This Mining leveling guide will show you the fastest way how to level your Legion Mining skill up from 1 to 100.