In mineralogy, tenacity is a mineral's behavior when deformed or broken.
The mineral breaks or powders easily. Most ionic-bonded minerals are brittle.[1]
The mineral may be pounded out into thin sheets. Metallic-bonded minerals are usually malleable.
The mineral may be drawn into a wire. Ductile materials have to be malleable as well as tough.
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.[2] Gold, for example, is sectile but pyrite ("fool's gold") is not.
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.
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.