Theyrium Material in Golarion | World Anvil


Theyrium is a greenish-black crystal that appears in geode clusters of translucent, sharp-edged crystals. The eldritch stones softly hum in dissonant tones and glow brightly at night or when exposed to magic. Deposits are found throughout Golarion, primarily in the Worldwound, but pockets have been found further south. Theyrium has long been considered less of an ore and more like a magical anchor binding the Abyss to the material plane.   A typical theyrium fragment is about the size of a finger. Crystals may be fist-sized or slightly larger, and geodes may be as big as a pumpkin. Massive clusters might grow taller than a human. Miners who discover theyrium fragments remark that the deposits end up in locations where they should not be, as if they were placed there rather than developed over time.   Mining theyrium is a challenge. Handling the ore without gloves or other protective measures can result in physical damage. Prolonged contact has resulted in the development of aberrant mutations, eventually leading to death. Those who have studied the ore have found that it seemed to share both arcane and divine signatures, possessing the ability to be "detected" as evil when exposed to alignment-detecting magics.


Material Characteristics

A dark-green crystal geode, with a blackness swimming within it.

Physical & Chemical Properties

  • Immune to bludgeoning, piercing, and slashing damage from nonmagical weapons.
  • Resistant to acid, cold, fire, and lightning damage; as well as slashing and piercing damage from magical weapons.
  • Vulnerable to bludgeoning damage from magical weapons.
  • Unless contained within an antimagic field, theyrium shatters and crumbles into worthless ash when reduced to zero hit points. However, theyrium geodes release a random arcane anomaly when destroyed, so cautious handling is advised.

History & Usage

Everyday use

  • Spell Component. Theyrium may be used as an arcane focus or material component for any arcane spell. When casting a spell which requires a costly material component, a spellcaster may instead use theyrium of equivalent value to the required cost.
  • Magic Items. Theyrium is an exceptional material for creating magical items of all kinds. Fragments, shards, crystals, and geodes may be used to make uncommon, rare, very rare, and legendary items.
  • Stable Theyrium. The process of crafting magic items with theyrium renders the crystals stable. Touching or handling stable theyrium does not result in aberrant corruption. Stable theyrium is damaged and destroyed in the same manner as normal magic item.
  • Theyrium Dust. Theyrium dust is made by grinding the crystals against one another to create a fine powder. This milling process is extraordinarily hazardous unless performed within an antimagic field. Theyrium dust can be used in alchemy, as a spell component, as a reagent for brewing potions, or mixed into inks for spell scrolls.


  • When a humanoid creature touches theyrium without protective gear (such as gloves or tongs), they can be subjected to aberrant contamination. This contamination is difficult to treat, and can eventually lead to madness, mutation, and / or death. 
Swirling Greenish-Black