Difference between Cleavage and Fracture

By: | Updated: May-28, 2019

Minerals are naturally occurring inorganic substances that can be found anywhere. They have distinctive properties that make them unique from one another. These properties also help us identify which types of mineral they are. One differentiating factor among certain minerals is the characteristic way they break when subjected to a certain amount of pressure or stress. Minerals can have what we call either a cleavage or a fracture upon breakage. This article will tell you more about this “breaking” property of minerals and how to tell them apart.

Summary Table

CleavageFracture
Breaking or splitting of minerals in crystallized shapeBreaking of a mineral in an irregular way, or chipping
Mostly full, smooth edgesMostly jagged edges
Has almost none to very few rough surfacesHas a lot of rough surfaces

Definitions

Cleavage in a mineral
Cleavage in a mineral

Cleavage is the characteristic property of a mineral that is exhibited in how it splits easily along a flat surface. Whenever a mineral is subjected to stress, breaks off, and retains a crystal shape, then it has cleavage. Cleavage in a mineral is measured by its quality and the number of sides having the cleavage. A mineral can have a perfect, good, or poor cleavage depending on its smoothness and absence of any rough edges.

Fracture in a mineral
Fracture in a mineral

Fracture is the characteristic way a mineral looks when it is subjected to stress and breaks off in an irregular way. All minerals can have fractures, but some just have more than others. A fracture can simply be described as the “chipping” of a mineral and this can happen in different ways depending on the shape or type of surface it exhibits.

Cleavage vs Fracture

The main difference between cleavage and fracture is the characteristic manner in which a mineral breaks when subjected to any form of pressure or stress. A cleavage is the resulting smooth plane in a mineral as a crystal face breaks off to form a new crystalline face. A fracture, on the other hand, refers to that rough-edged, chipped shape of a mineral.

When minerals form a cleavage, they exhibit mostly full,smooth surfaces and very few rough edges. Conversely, fractures in a mineral will showcase mostly jagged edges and rough surfaces.

Cleavage can be measured by quality and the number of sides exhibiting that property. A perfect cleavage leaves no fragment and has a full, smooth edge without any rough surfaces. Good cleavage means that it cleaves well with some rough surface. Poor cleavage has a more dominant rough surface. Most minerals exhibit cleavage only on one side but some have different quality cleavage on different sides.

A mineral can also have different types of a fracture. One can be “conchoidal,” meaning it resembles a semicircular shell with a smooth, curved surface. Another is called an “uneven” fracture, which is one that has an irregular surface. Others are “hackly,” (resembles broken metal) “splintery,” (forms elongated splinters) and “earthy” (those what crumble when broken.)

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