Sigmarite is the blessed metal from which the arms and armour of the Stormcast Eternals are forged. Its source is Mallus, the broken metallic core of the world destroyed before the current age, which now hangs in the heavens of Azyr above the palace-city of Sigmaron. Sigmar himself is said to have been found clinging to Mallus as it tumbled through the void, and the ore mined from it carries echoes of divine power.
Worked in the celestial forges under the guidance of Grungni, the great smith-god, sigmarite is stronger and lighter than any mortal steel and holds enchantment the way other metals hold an edge. It shrugs off blows that would shear through iron, resists the corrupting touch of Chaos, and channels the storm-magic bound into every Stormcast warrior. Hammers, blades, shields, and the distinctive thunderbolt-crested plate of the Stormhosts are all shaped from it.
Beyond weaponry, the metal anchors Sigmar's reconquest of the realms. Stormkeeps and fortress-cities are raised around sigmarite cores, and its presence is treated as both a practical bulwark and a symbol: proof that some fragment of the lost world endures, hammered into a shape that fights back.