Iron Ore Valheim 1.0.20
Iron Ore is a crafting material that stacks to 30 in Valheim.
“Unrefined iron. Needs to be refined in a smelter.”
Iron Ore is a material described in the game as unrefined iron that needs to be refined in a smelter. You can't use it as it is, so it has to go through that step first.
Each piece weighs 10, and you can carry up to 30 in a single stack. Iron Ore cannot be teleported, so you have to carry it by hand rather than sending it through a portal.
Other material items
Acorns, 
Amber, 
Amber Pearl, 
Ancient Bark, 
Ancient Coin, 
Ancient Metal, 
Ashlands Gourmet Bowl, 
Ashwood, 
Asksvin Bladder, 
Asksvin Hide, 
Asksvin Neck, 
Asksvin Pelvis.