There are two physical properties of minerals that both result in smooth, flat surfaces with specific angles between them. The first property is externally visible and is the result of how the mineral forms; the second is inherently internal and is the result of breaking a sample of the mineral. These properties are called:.
1. hardness and cleavage.
2. cleavage and hardness.
3. crystal habit and cleavage.
4. cleavage and crystal habit.