Mining Rune Essence
To mine essence or use the runecrafting skill, you must complete the ̶0;Rune Mysteries̶1; quest, given by the head wizard Sedridor at the Wizard's Tower. As soon as you complete the quest, you will be teleported to the mine by a nonplayer character, or NPC. Use your pickaxe on the rune essence and mine until you have filled your inventory, then leave via the closest portal. You can only reach the mine by asking an appropriate NPC to teleport you.
Types
Rune essence comes in several types: air, water, earth, fire, mind or body. Paid members of "RuneScape" can also access a special type of essence, called pure essence, that has no elemental alignment. You must use this special essence if you want to make member-only craftable runes, and you cannot trade it with non-member players. Ordinary rune essence works to make the rune type that matches its alignment, and can be traded with anyone.
Trading
You can buy or sell rune essence on the game's Grand Exchange. Rune essence is among the most commonly traded items on the exchange, and can be a reliable source of in-game income. At the time of publication, rune essence sells for 18 gold pieces on the Grand Exchange. This price fluctuates periodically. For instance, in mid-July of 2011, rune essence rose to a high of 24 gold pieces, then fell to 17 by the end of the month.
Considerations
Game rules restrict how you can buy and sell rune essence, to protect game balance. For instance, you can buy only 25,000 rune essence every 4 hours in the Grand Exchange. Jagex also forbids trading rune essence, gold or any other in-game item for real-world money, and discourages players from using macros to mine large amounts of essence solely for profit. Using automated characters, or bots, as miners is against the game's terms of service.