Here's why:
* Crystal Structure: The specific, ordered arrangement of atoms within a mineral determines its shape, cleavage, and many other physical properties.
* Cleavage: The tendency of a mineral to break along specific planes of weakness, which are directly related to the arrangement of atoms.
* Hardness: The resistance of a mineral to scratching, which is influenced by the strength of the bonds between atoms.
* Fracture: The way a mineral breaks when it doesn't cleave, also related to the atomic structure.
* Density: The mass per unit volume of a mineral, which is directly related to the atomic packing and types of atoms present.
In essence, the internal structure of a mineral dictates its external properties.
