Question

The luster and crystal system of a Topaz mineral respectively are:

• A. metallic and triclinic
• B. greasy and tetragonal
• C. dull and monocline
• D. vitreous and orthorhombic

Hint:

Topaz displays a shiny, glass-like luster and belongs to the orthorhombic crystal class.

Answer 1

The Correct Option is D

To determine the correct luster and crystal system of topaz, we examine its mineralogical properties.

1. Understanding Topaz Characteristics:
Topaz is a well-known silicate mineral that occurs in various colors and is valued as a gemstone.

2. Luster of Topaz:
- Topaz exhibits a vitreous (glass-like) luster when freshly broken or properly cut.
- This is the most characteristic luster for quality topaz specimens.

3. Crystal System of Topaz:
- Topaz crystallizes in the orthorhombic crystal system.
- This system is characterized by three mutually perpendicular axes of unequal length.

4. Eliminating Other Options:
- Metallic luster and triclinic system are incorrect for topaz
- Greasy luster and tetragonal system don't match topaz properties
- Dull luster and monoclinic system are also incorrect

Conclusion:
The accurate description of topaz is vitreous luster with orthorhombic crystal structure.

Final Answer:
The correct option is: vitreous and orthorhombic.