Question

Zircon type crystals may be designated as having:

• A. 5 planes, 5 axes and no centre
• B. 5 planes, 3 axes and no centre
• C. 3 planes, 5 axes and centre
• D. 5 planes, 5 axes and centre

Hint:

Zircon is a common example used for tetragonal crystal symmetry.

Answer 1

The Correct Option is D

Concept:
Zircon is an important mineral of the tetragonal crystal system. The symmetry of crystals is described by symmetry planes, axes and centre.

Step 1: Identify the crystal type.
Zircon belongs to the tetragonal system and is commonly used as an example of high symmetry tetragonal crystals.

Step 2: Symmetry elements.
Zircon type crystals are described as having: \[ 5 \text{ planes} \] \[ 5 \text{ axes} \] \[ 1 \text{ centre of symmetry} \]

Step 3: Select the matching option.
The option matching this description is: \[ 5 \text{ planes, } 5 \text{ axes and centre} \] \[ \therefore \text{Correct Answer is (D)} \]