Here's why:

* Crystalline Structure: Minerals are formed by a specific, repeating arrangement of atoms in a three-dimensional structure called a crystal lattice. This ordered structure gives minerals their unique physical properties like cleavage, hardness, and crystal form.

* Natural Occurrence: Minerals are naturally occurring, meaning they are not created in a laboratory or through human intervention.

* Inorganic: Minerals are inorganic, meaning they are not derived from living organisms.

* Solid at Room Temperature: With the exception of mercury, all minerals are solid at room temperature.

While some minerals may be amorphous (lacking a defined crystal structure), the vast majority exhibit crystalline structure.