Mineral cleavage

Welcome to the seventh episode of the Mineralogy and Crystallography course! Building upon our previous discussions on mineralogy, crystals, crystal systems, the Mohs scale, silicate minerals, and native element minerals, this episode focuses on mineral cleavage. Cleavage is a fundamental property of minerals that describes how they break along specific planes of weakness in their crystal structure. We'll explore the different types of cleavage, how to identify them, and how cleavage relates to the internal arrangement of atoms within a crystal. Understanding cleavage is essential for mineral identification and provides valuable insights into the atomic structure of minerals. It's one of the key physical properties used alongside the hardness, and other characteristics we have covered.

Check your understanding

These are the same multiple-choice questions you will see in the Quiz section after you listen to the episode. Use them here to preview or review the answers.

What is mineral cleavage?

  1. The color of a mineral.
  2. The way a mineral reflects light.
  3. The tendency of a mineral to break along specific planes of weakness.
  4. The hardness of a mineral.
  5. The shape of a mineral crystal.
  6. The streak a mineral leaves

What determines the cleavage planes in a mineral?

  1. The mineral's color.
  2. The mineral's hardness.
  3. The internal arrangement of atoms and the strength of chemical bonds.
  4. The way the mineral was formed.
  5. The size of the mineral crystal.
  6. The temperature at which the mineral forms.

What is the difference between cleavage and fracture?

  1. Cleavage produces smooth, flat surfaces, while fracture produces irregular surfaces.
  2. Cleavage is always perfect, while fracture is always poor.
  3. Cleavage is found only in metallic minerals, while fracture is found only in nonmetallic minerals.
  4. Cleavage is a chemical property, while fracture is a physical property.
  5. There's no difference.
  6. Cleavage describes color, Fracture describes luster

How is the quality of cleavage described?

  1. By its color.
  2. By its hardness.
  3. By terms like perfect, good, distinct, poor, or indistinct.
  4. By the number of cleavage directions.
  5. By its Miller indices.
  6. Using the Mohs Scale.

A mineral breaks into thin, flat sheets. What type of cleavage does it exhibit?

  1. Cubic cleavage
  2. Octahedral cleavage
  3. Basal cleavage
  4. Rhombohedral cleavage
  5. Prismatic cleavage
  6. Conchoidal fracture

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