Here's why:

* Core: The Earth's core is thought to be composed primarily of iron and nickel, but it also contains significant amounts of sulfur, along with other elements like silicon and oxygen. The sulfur is likely present in the form of iron sulfide.

* Mantle: Sulfur is also present in the mantle, but in smaller amounts than the core. It is often found in compounds like sulfides and sulfates.

* Crust: Sulfur is found in the Earth's crust, but it is more concentrated in certain locations like volcanic areas and sedimentary deposits.

While sulfur is present throughout the Earth, its concentration is highest in the core, making it a key component of this deep Earth layer.