Physical Properties of Minerals Quiz

Physical Properties of Minerals

• Luminescence: Minerals exhibit luminescence when absorbing electromagnetic radiation (like UV light) and re-emitting light at a different wavelength. Fluorescence (light during illumination) and phosphorescence (light after illumination) are types of luminescence. Different minerals show different luminescence colors and intensities due to their composition and structure.

• Streak: Streak is the color of a mineral's powder when scratched on an unglazed porcelain plate. It can be the same or different from the mineral's external color. Streak is consistent for a given mineral, regardless of variations in crystal size or color. It aids in mineral identification.

• Habit: Mineral habit describes the general shape of a mineral crystal or cluster. It varies with formation conditions. Common habits include:

  • Crystalline: Well-formed, regular geometric shapes (e.g., cubes, prisms, octahedrons).
  • Massive: No discernible crystal shape; the mineral is compact, blocky, or granular.
  • Fibrous: Long, thread-like crystals.
  • Acicular: Needle-like crystals.
  • Columnar: Pillar-like crystals.
  • Granular: Small, interlocking crystals or grains.

Odour

• Minerals usually have no significant or noticeable odor in their natural state. This is because minerals are largely inorganic and not typically associated with volatile compounds creating smells.

Electrical Properties

• Some minerals exhibit electrical conductivity, a measure of how easily electric current flows. This depends on the mineral's structure and chemistry. Minerals with free-moving ions or electrons tend to be conductive. Examples include graphite (good conductor) and various sulfides (variable conductivity).
• Other minerals are insulators, not easily conducting electricity. Many oxides and carbonates are insulators.
• Electrical conductivity differs from piezoelectric or pyroelectric properties. These involve electricity generated by mechanical stress (piezoelectricity) or temperature change (pyroelectricity), but not a constant current flow.