Brooklyn College - Earth And Environmental Sciences - Minerals - Cleavage And Fracture

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MINERALS

Cleavage and Fracture

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Cleavage is the tendency of a mineral to break along smooth planes parallel to zones of weak bonding.

Fracture is the tendency of a mineral to break along curved surfaces without a definite shape. These minerals do not have planes of weakness and break irregularly. See the picture below:

Mineral Cleavage Test Video

Mineral Cleavage and Fracture Test Video

Mineral	Type of Breakage
Halite
	CLEAVAGE Cleavage in three directions at right angles (90o). Cubic cleavage.
Calcite
	CLEAVAGE Cleavage in three directions not at right angles (120o and 60o). Rhombohedral cleavage.
Gypsum
	CLEAVAGE Cleavage in one direction.
Muscovite
	CLEAVAGE Cleavage in one direction.
Feldspar
	CLEAVAGE Cleavage in two directions at right angles.
Quartz
	FRACTURE Mineral does not exhibit cleavage, it breaks or fracture in an irregular manner.