Tungsten

Tungsten Ore is an ore found beneath the surface, it can be smelted into ingots which make a custom armour and tool set. These are worse than iron, but are compensated with the fact the ore spawns more frequently and in larger chunks than iron.

After the ore is smelted, like any normal ore it can be crafted with sticks in the regular places in the crafting table to create tools, vice versa just without the need of sticks for the armour.

Other than being used in a few random recipes and being in the loot table of the Floating Island and Tower Ruin chests, that is really what tungsten is used for.