In mineralogy, tenacity is a mineral's resistance to deformation or breakage. Along with hardness, it determines the durability of a mineral.
Common terms There are several common terms that are used to describe the tenacity of a mineral.
Brittleness
The mineral breaks or powders easily. Most ionic-bonded minerals are brittle.
Malleability
The mineral may be pounded out into thin sheets. Metallic-bonded minerals are usually malleable.
Ductility
The mineral may be drawn into a wire. Ductile materials have to be malleable as well as tough.
Sectility
May be cut smoothly with a knife. Relatively few minerals are sectile. Sectility is a form of tenacity and can be used to distinguish minerals of similar appearance. Gold, for example, is sectile but pyrite ("fool's gold") is not.
Elasticity
If bent by an external force, an elastic mineral will spring back to its original shape and size when the stress, that is, the external force, is released.
Plasticity
If bent by an external force, a plastic mineral will not spring back to its original shape and size when the stress, that is, the external force, is released. It stays bent.
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