Others break in two or more directions. Some common forms of cleavage are cubic, rhombohedral, and basal. If a mineral breaks easily and cleanly in one or more directions, its cleavage is considered perfect. For example, calcite cleaves perfectly along three planes. As the quality of the break decreases, cleavage may be described as good, distinct, and poor or none.
Some minerals cleave perfectly in one direction and poorly in others.
For example, gypsum cleaves perfectly on one plane and poorly along two others. Fracture Not all minerals cleave easily. Some fracture instead. Specific Gravity Specific gravity is the density of a mineral. Special equipment is usually needed to find out a mineral s exact specific gravity.