Optical mineralogy

Episode 9 of Mineralogy and Crystallography introduces optical mineralogy, a crucial technique for mineral identification. Building upon our understanding of mineral properties, crystal systems, and the Mohs scale, we will explore how polarized light interacts with minerals. We will examine the use of a petrographic microscope and learn about properties like birefringence, extinction, and pleochroism. This episode will equip you with the knowledge to use optical properties for mineral identification, preparing you for more advanced mineralogical techniques.

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.

Optical mineralogy uses which type of light?

  1. Unpolarized light
  2. Polarized light
  3. Infrared light
  4. Ultraviolet light

A key instrument in optical mineralogy is the:

  1. Scanning electron microscope
  2. X-ray diffractometer
  3. Petrographic microscope
  4. Atomic force microscope

Birefringence refers to:

  1. The color of a mineral
  2. The difference in refractive index
  3. The hardness of a mineral
  4. The shape of a crystal

Pleochroism is the property of a mineral exhibiting:

  1. Different colors in different directions
  2. The same color in all directions
  3. No color at all
  4. Interference colors

Isotropic minerals belong to which crystal system?

  1. Tetragonal
  2. Orthorhombic
  3. Monoclinic
  4. Cubic

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