Question

Which one of the following minerals belongs to the cubic (isometric) crystal system?

• A. Quartz
• B. Orthoclase
• C. Galena
• D. Gypsum

Hint:

Common cubic system minerals include {Galena, Halite, Pyrite, and Magnetite}. Memorizing these helps in quick elimination.

Answer 1

The Correct Option is C

To determine which mineral belongs to the cubic (isometric) crystal system, we need to understand the crystallography of the given minerals.

1. Cubic (Isometric) Crystal System: This system is characterized by three axes of equal length intersecting at right angles. Minerals crystallizing in this system typically have high symmetry.
2. Options Explanation:
   • Quartz: This mineral belongs to the hexagonal crystal system, characterized by sixfold symmetry.
   • Orthoclase: This belongs to the monoclinic crystal system, which has axes of unequal length, with one of the angles being oblique.
   • Galena: This mineral belongs to the cubic (isometric) system. It often forms cubic crystals and has perfect cubic cleavage, typical of the isometric system.
   • Gypsum: This belongs to the monoclinic crystal system, similar to orthoclase, with one of the angles being oblique.
3. Conclusion: Based on the crystallographic systems, Galena is the mineral that belongs to the cubic (isometric) crystal system.