You can do granite mining really fast with one of these 3 methods:
But first of all, I'm gonna show you how and when to drop the granite. Mine 1 granite. Click the next rock, then right click the 1 granite in your inventory and the second you get the next granite drop the one you had right clicked. Anyways, here are the 3 methods I mentioned:
1. Just use a full inventory of waterskins (except 1 slot)
2. Complete dream mentor and achieve 68 magic and use the Humidify spell (fills waterskins with water) However this will require 3 free inventory spots (1 astral rune, 3 water runes, and 1 fire rune.)
3. Complete dealing with the scabaras quest to get the enchanted water tiara. (If you wear this in the desert, you won't need waterskins)
So yeah, good luck training your mining
