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
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.

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©Guillermo Rocha/Brooklyn College