Cleavage

Definition

Cleavage refers to the tendency of a mineral to break along specific planes of weakness, creating smooth, flat surfaces. This property is crucial in identifying minerals because it reveals the arrangement of atoms within their crystal structures, influencing how they interact with light and other substances. Different minerals exhibit varying degrees and directions of cleavage, which can provide insight into their classification and underlying geological processes.

5 Must Know Facts For Your Next Test

1. Cleavage is classified by its quality, such as perfect, good, or poor, depending on how well a mineral breaks along its cleavage planes.
2. Some minerals exhibit multiple cleavage directions, such as mica, which shows perfect cleavage in one direction.
3. The angle between cleavage planes can be measured and is important for mineral identification; for example, feldspar has two cleavage directions at right angles.
4. In contrast to cleavage, some minerals break unevenly due to irregular atomic bonding and this property is known as fracture.
5. Cleavage plays a significant role in industrial applications; for instance, minerals like gypsum are prized for their ability to be easily split into thin sheets.

Review Questions

• How does cleavage assist in the identification and classification of minerals?
  • Cleavage is a key property used to identify and classify minerals because it provides insight into their internal atomic structure. Minerals with distinct cleavage patterns can be linked to specific groups based on their crystal structures. By observing how a mineral breaks along these planes—whether it displays perfect or poor cleavage—geologists can narrow down the possible identity of the mineral and understand its formation process.
• Compare and contrast cleavage with fracture in terms of their implications for understanding mineral properties.
  • Cleavage and fracture are two distinct ways that minerals break, each offering valuable information about their properties. Cleavage occurs along specific planes due to weaker bonds between atoms, resulting in smooth surfaces that can help identify minerals. In contrast, fracture happens when minerals break irregularly without any preferred planes, indicating stronger atomic bonds. Understanding these differences helps geologists deduce not only the identity of a mineral but also its potential applications and stability in various environments.
• Evaluate the significance of cleavage angles in mineral classification and how this knowledge impacts geological studies.
  • The angles of cleavage are significant in mineral classification as they provide essential data regarding the arrangement of atoms within a crystal structure. By evaluating these angles, geologists can better categorize minerals into families based on similar properties. This knowledge impacts geological studies by aiding in resource identification and extraction strategies, as well as helping researchers understand geological history through mineral formation processes and conditions.

Related terms

Fracture: Fracture describes the way a mineral breaks when it does not cleave along its natural planes, resulting in irregular surfaces.

Crystal Structure: Crystal structure refers to the orderly arrangement of atoms in a mineral, which determines its physical properties, including cleavage.

Luster: Luster is the way a mineral reflects light, which can be influenced by its cleavage and surface characteristics.