Sectility is the ability of 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. ...

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 appearance, and is a form of

tenacity Tenacity may refer to: * Tenacity (psychology), having persistence in purpose * Tenacity (mineralogy) a mineral's resistance to breaking or deformation * Tenacity (herbicide), a brand name for a selective herbicide * Tenacity (textile strength) * ...

. For example,

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 ...

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. Sectility in metals is a result of

metallic bond Metallic bonding is a type of chemical bonding that arises from the electrostatic attractive force between conduction electrons (in the form of an electron cloud of delocalized electrons) and positively charged metal ions. It may be descr ...

ing, where

valence Valence or valency may refer to: Science * Valence (chemistry), a measure of an element's combining power with other atoms * Degree (graph theory), also called the valency of a vertex in graph theory * Valency (linguistics), aspect of verbs rel ...

(bonding) electrons are delocalized and can flow freely between atoms, rather than being shared between specific pairs or groups of atoms, as in covalent bonding.

References

Mineralogy {{Geology-stub