It's important to understand that rocks are not minerals. Rocks are made up of minerals, which are naturally occurring, solid substances with a defined chemical composition and a specific crystal structure.

Here are the five characteristics that define a mineral:

1. Naturally occurring: Minerals form through geological processes, not artificial creation.

2. Solid: Minerals are rigid and have a definite shape and volume.

3. Inorganic: Minerals are not derived from living organisms.

4. Definite chemical composition: Each mineral has a specific chemical formula, with consistent ratios of elements.

5. Ordered internal structure: Minerals have a regular, repeating arrangement of atoms, forming a crystal lattice.

Therefore, a rock cannot be classified as a mineral. Instead, rocks are aggregates of one or more minerals (like granite, which is made of quartz, feldspar, and mica) or non-mineral materials (like coal, which is made from organic matter).