White Iron Chunk is a farmable resource in the Genshin impact. It can be found all over the map in general wild areas, even in Mondstadt, but it is quite common in the Stormbearer Mountains (a high difficulty area of the game) and Wolvendom as you travel to Stormterror’s Lair.
It can also be found in abundance near Mt. Aozang, between Lingju Pass and Mt. Tianheng, and between Dawn Winery and Stone Gate.
You can gather White Iron Chunks by attacking them with your weapon until they break, then collecting the drops. It can be refined at the Blacksmith and will result in Fine Enhancement Ore. Fine Enhancement Ore can be used to level up your weapons, and will provide 2000 Weapon EXP when you use it. It is a good idea to keep some White Iron Chunks unrefined, as you will need it to build new weapons for your characters.
As you play through the game, it is a great idea to just farm all the resources that you run into, even if you don’t need them at that particular time. It will save you have to scour the map to try and find them if you build up a large supply of resources as you discover them.