Brittleness

The mineral breaks or powders easily. Most ionic-bonded minerals are brittle.^[1]

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.^[2] 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.

Common terms