Pure essence is a raw material used in the Runecraft skill to make members only runes. They can create the same runes as rune essence as well as cosmic, chaos, astral, nature, law, death, wrath and any combination runes. Pure essence does not provide any bonus over rune essence when crafting runes lower than cosmic runes; therefore, when crafting lower-tier runes, it is recommended to use whichever essence is less expensive at the time.
Zulrah, Old School RuneScape Wiki
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Guardian essence - OSRS Wiki
Blood rune - OSRS Wiki
Logged in half asleep, within 3 minutes the dopamine got me wide awake : r/ironscape
Mining rune essence - OSRS Wiki
How to Mine Rune Essence: 7 Steps (with Pictures) - wikiHow
RuneScape - Ultimate Pure Essence Mining Guide
Dense essence block - OSRS Wiki
Mud rune, Old School RuneScape Wiki
Mining pure essence, Old School RuneScape Wiki
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Cosmic rune - OSRS Wiki
Mind rune - OSRS Wiki