Here's why:

* Definite chemical composition: Minerals have a specific, consistent chemical formula.

* Crystalline structure: The atoms in a mineral are arranged in a highly ordered, repeating pattern, forming a crystal lattice. This ordered arrangement gives minerals their characteristic shapes and properties.

* Naturally occurring: Minerals form naturally through geological processes.

* Solid: The atoms in a mineral are tightly bound together, giving it a rigid, solid structure.

While some minerals can be found in liquid or gaseous states under extreme conditions, they are primarily considered solid materials.