The rune essence mine can only be accessed upon completion of the Rune Mysteries Quest. This dungeon contains four essence spires, where you can mine both pure essence and normal essence. Pure essence can only be mined on members servers if you have over level 30 mining, while normal essence can only be mined on free servers or on members if you have less than level 30 mining. Once you've done the quest, you learn of wizards who have the ability to open a rift and teleport you to the essence mines. These wizards can be found in the Wizard Tower, Ardougne, Tree Gnome Stronghold, Magic Guild and Varrock. To get out of the mine, click on the small portals that are beside the essence stack.