“Used for alchemy spells.”
The Nature rune is the fuel behind every High Alchemy cast — the single item you spend to alch everything else. It's also one of the most-traded runes in the game, and its live price drives every alch-profit figure on this site.
One nature rune is consumed per High Alchemy cast (currently about 134 gp). It's the running cost every alch-profit calculation subtracts.
Beyond alchemy, nature runes power many combat and utility spells. Active casters buy them thousands at a time, and their deep volume makes them a common low-margin flip.
For the record: a nature rune's own alch value (108 gp) is below its price, so alching them is a small loss — they're something you spend, not something you convert.
Prices move — open the calculator to see this item's current alch-vs-sell verdict and profit per buy limit.
One nature rune per cast, plus the fire runes supplied by a fire or combination staff. That single nature rune is the main running cost of alching.
Most players buy them on the Grand Exchange for alching, but they can also be crafted at the Nature altar with pure essence (Runecraft), a popular money-maker at higher levels.
Around 134 gp at the live Grand Exchange price shown above. It moves with demand from alchers and spellcasters.