* Elements are the fundamental building blocks of matter and cannot be broken down into simpler substances. Iron (Fe) and sulfur (S) are both elements.

* Iron sulfide (FeS) is a compound, meaning it's formed by the chemical combination of two or more elements.

* Compounds have properties that are different from the elements they are made of. For example, iron sulfide is a black solid, while iron is a silvery metal and sulfur is a yellow powder.

So, while iron sulfide contains the metallic element iron, it is itself not a non-metallic element. It's a compound with its own unique properties.