1. Naturally Occurring: Minerals must form in nature, not through human processes.
2. Solid: They must have a definite shape and volume at room temperature.
3. Inorganic: They cannot be formed by living organisms.
4. Crystalline Structure: Minerals have an ordered, repeating arrangement of atoms.
5. Definite Chemical Composition: Each mineral has a specific chemical formula, though some can have slight variations.
These characteristics work together to define minerals and distinguish them from other materials found in the Earth's crust.