Basal Cleavage

Definition

Basal cleavage refers to a type of mineral cleavage that occurs parallel to the base or the principal plane of a crystal. This feature is significant in the identification and classification of minerals, particularly native elements, as it influences how minerals break and how they are structurally organized. Understanding basal cleavage helps in determining the physical properties of minerals, including their luster and habit, which are crucial for classification.

5 Must Know Facts For Your Next Test

1. Basal cleavage is especially prominent in minerals with layered structures, such as mica and graphite, where sheets can easily separate.
2. The presence of basal cleavage can significantly affect the hardness of a mineral, as it creates planes that are weaker compared to the overall structure.
3. In native elements, basal cleavage may influence how the mineral appears in nature, affecting its aesthetic and practical applications.
4. Understanding basal cleavage is vital for gemologists and mineralogists, as it aids in differentiating similar-looking minerals based on their cleavage patterns.
5. When identifying minerals, observing the presence or absence of basal cleavage can provide insights into their crystallography and underlying atomic arrangement.

Review Questions

• How does basal cleavage influence the physical properties of minerals, and why is it significant in mineral identification?
  • Basal cleavage influences the physical properties of minerals by determining how they break and their overall structural integrity. This type of cleavage can affect hardness and shape, making it easier to distinguish between similar minerals during identification. In essence, understanding basal cleavage allows mineralogists to classify minerals based on how they interact with light and their breaking patterns.
• Compare and contrast basal cleavage with other types of cleavage in minerals, and discuss their implications on mineral classification.
  • Basal cleavage differs from other types of cleavage, such as cubic or rhombohedral cleavage, by specifically occurring parallel to the base of the crystal. While basal cleavage creates flat surfaces that facilitate separation along planes, cubic cleavage results in cubic fragments and rhombohedral cleavage leads to angled breaks. These differences are crucial for classification as they provide distinctive characteristics that help identify minerals based on their structural features.
• Evaluate the importance of basal cleavage in understanding the geological processes that form native elements and their subsequent applications.
  • Basal cleavage plays a significant role in understanding geological processes by revealing how certain native elements form under specific conditions. The arrangement of atoms that allows for basal cleavage indicates the environment in which these minerals crystallized. This knowledge not only aids geologists in reconstructing geological history but also informs practical applications such as resource extraction and material use in various industries.

Related terms

Cleavage: The tendency of a mineral to break along specific planes of weakness, which are determined by the arrangement of atoms in the mineral's crystal structure.

Fracture:

The way a mineral breaks other than along its cleavage planes, often resulting in uneven or irregular surfaces.

Crystal Habit:

The typical shape and external appearance of a crystal, influenced by its internal arrangement of atoms and growth conditions.