Rune dust

Rune dust can be made by using a hammer or a chisel on a rune essence or pure essence stone to crack them into rune shards, and then grinding these down in a pestle and mortar.

Rune shards and rune dust appear in the Garden of Tranquility quest, when rune dust must be added to a plant cure potion to revive some badly damaged vines in Bernald's garden behind the bar in Burthorpe.