Iron

Delver's Harvest by Cortney Skinner

Iron was a commonly used metal in Middle-earth, though it was perhaps most infamously used in the Iron Crown. In Sindarin it was called ang.

The gate of High Hay has thick-set iron bars. The Orcs of Isengard wore iron helmets.

Portrayal in adaptations

1994: Middle-earth Role Playing—Treasures of Middle-earth

Much is made of the purity of iron in the book. Pure iron is silver-white and easiest to work with, though it is rare even Moria, while more common varieties are darker and stronger. The Dwarves considered anything that's “virtually pure” iron to be iron. The Elves primarily used iron to make steel.

2007: The Lord of the Rings Online:

Barrow-iron ore can be mined by journeyman prospectors in Cardolan, Ered Luin, the Shire, Bree-land, the Lone-lands, and the North Downs. Rich iron ore can be mined by expert prospectors in the Lone-lands, the North Downs, Evendim, Bree-land, and the Yondershire. Dwarf-iron ore can be mined by artisan prospectors in the Trollshaws, the Misty Mountains, Angmar, Evendim, and the Lone-lands. Ancient iron ore can be mined by master prospectors in the Misty Mountains, Angmar, Forochel, Eregion, and Bree-land.