Minerals.

Minerals, also known as mineral species are parts of rocks and chemical elements.

There are many different minerals. Calcium (Ca), phosphorus (P), and iodine are minerals, too.

These elements are found in the bowels of the Earth.

Minerals are used in various fields.

Source of image:

https://www.shutterstock.com/image-photo/pyrite-mineral-crystalpyrite-crystal-396999130