In mineralogy, tenacity is a

mineral In geology and mineralogy, a mineral or mineral species is, broadly speaking, a solid chemical compound with a fairly well-defined chemical composition and a specific crystal structure that occurs naturally in pure form.John P. Rafferty, ed. (2 ...

's behavior when deformed or broken.

Common terms

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 Ductility is a mechanical property commonly described as a material's amenability to drawing (e.g. into wire). In materials science, ductility is defined by the degree to which a material can sustain plastic deformation under tensile str ...

:
The mineral may be drawn into a wire. Ductile materials have to be malleable as well as tough.

Sectility Sectility is the ability of a mineral to be cut into thin pieces with a knife. Minerals that are not sectile will be broken into rougher pieces when cut. Metals and paper are sectile. Sectility can be used to distinguish minerals of similar appea ...

:
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 Gold is a chemical element with the symbol Au (from la, aurum) and atomic number 79. This makes it one of the higher atomic number elements that occur naturally. It is a bright, slightly orange-yellow, dense, soft, malleable, and ductile me ...

, for example, is sectile but

pyrite The mineral pyrite (), or iron pyrite, also known as fool's gold, is an iron sulfide with the chemical formula Fe S2 (iron (II) disulfide). Pyrite is the most abundant sulfide mineral. Pyrite's metallic luster and pale brass-yellow hue giv ...

("fool's gold") is not. Elasticity:
If bent, will spring back to its original position when the stress is released. Plasticity:
If bent, will not spring back to its original position when the stress is released. It stays bent. In contrast, flexibility is the ability of a material to deform elastically and return to its original shape when the applied stress is removed.

References

{{Geology-stub Mineralogy Deformation (mechanics) Materials science