The iron nugget is an item that is added by the Evil Minecraft mod. It looks like the gold nugget in vanilla Minecraft.
Crafting[]
If you place one Iron Ingot in any space on a crafting menu, then that will result in you making 9 Iron Nuggets. If you fill each space with an iron nugget on a crafting bench, then you will make an Iron Ingot. Iron nuggets can be used to create lockpicks and pet tags. Other than that, they have no known practical use.