Which of the following is not a characteristic of a crystal?

a. The arrangement of the atoms in a crystal determines its shapes.
b. A crystalline structure is always geometric.
c. Crystals are classified according to their mineral content.

Please do not double post.

To determine which of the options is not a characteristic of a crystal, we can analyze each option.

a. The arrangement of the atoms in a crystal determines its shapes.
This statement is true. The repeating arrangement of atoms in a crystal determines its distinct shapes and forms.

b. A crystalline structure is always geometric.
This statement is also true. Crystals have a highly ordered and repetitive arrangement of atoms, resulting in a symmetric and geometric pattern.

c. Crystals are classified according to their mineral content.
This statement is not true. Crystals are classified based on their internal structure and the arrangement of their atoms, not their mineral content. The mineral content may vary for different crystals of the same mineral species.

Therefore, the option that is not a characteristic of a crystal is:

c. Crystals are classified according to their mineral content.