FFXIV Vanadinite is a crafting material introduced in Patch 6.2 during Endwalker. It can be acquired in exchange for 20 Allagan Tomestones of Astronomy.
Specifically, players should speak to the Tomestone Exchange NPC in Radz-at-Han: Cihanti (X: 10.8, Y: 10.4). For reference, she’s located in the Western Balshahn Bazaar — to your lefthand side as you enter from the Radz-at-Han Aetheryte Plaza. Speak to her and select the option “Allagan Tomestones of Astronomy (Other)” to see the Vanadinite available for purchase.
Two pieces of Vanadinite are needed alongside five pieces of Ilmenite to craft one Ilmenite Ingot. This is a Level 90 master recipe that requires the Master Armorer X tome or the Master Blacksmith X tome to first be used on the player intending to craft it. The two “different” recipes are identical — except that Armorers need Ice Clusters for the craft while Blacksmiths need Fire Clusters instead.
Ilmenite Ingots are then used in a variety of other Level 90 master recipes also tied to X-level tomes. Such as the Rinascita Cuirass of Maiming.
Assuming the maximum cap of 2,000 Tomestones in players’ inventory at one time, it’s possible to purchase 100 units of Vanadinite in one trip. Though there are several other types of Patch 6.2 crafting material also needed for Level 90 gear.
There is currently no other way to gather, purchase, or craft Vanadinite in FFXIV. Though players can trade it on the in-game Market Board.
