Iron Nugget

An iron nugget is an item obtained by smelting iron tools, weapons, or iron/chainmail armor.

Smelting
Durability and enchantments do not affect the ability to smelt iron tools, weapons, or armor into iron nuggets.

Bartering
Piglins may barter 9–36 iron nuggets when given a gold ingot.

Usage
Iron nuggets are used to craft iron ingots, lanterns, soul fire lanterns, and chains.

Trivia

 * From the iron nuggets introduction in 1.11.1 to the Village and Pillage update in 1.14, it was the first and only completely useless item in Minecraft (so far), only being used for iron ingots, which can also make iron nuggets, so it was only useful in itself. It wasn't used in any crafting recipes (except iron ingots), and it took 9 iron nuggets to make one ingot, which made it not really worth smelting iron tools and armor for just one iron nugget. It changed when they added lanterns in 1.14, which required 8 iron nuggets in its crafting recipe, and 1.16, when they added chains and soul lanterns, which required 2 and 8, respectively.