* Crystals grow from a seed: Minerals form when atoms come together in a specific, repeating pattern. This pattern is called a crystal lattice.
* Crystal faces reflect the lattice: The external shape of a crystal (its faces) is determined by the internal arrangement of atoms in the lattice. If the arrangement is highly ordered, the resulting crystal shape will be symmetrical.
* Symmetry indicates specific properties: The symmetry of a crystal can be described by a set of symmetry operations, such as rotations, reflections, and inversions. These operations are directly linked to the arrangement of atoms in the lattice. This, in turn, determines many of the mineral's properties, like cleavage, hardness, and even optical properties.
Here's an example:
Imagine building a structure with LEGO blocks. If you follow a specific, repeating pattern, you'll end up with a structure that has symmetry. Similarly, the internal arrangement of atoms in a mineral determines its external shape, and the higher the symmetry, the more ordered the internal structure.
In summary:
* Symmetrical crystal shapes indicate an ordered internal atomic structure.
* This ordered structure determines many of the mineral's properties.
* The symmetry of a crystal is an important tool for identifying minerals.
