Question

Polymorphic minerals have

• A. different crystal forms and identical composition
• B. different crystal forms and different compositions
• C. identical crystal form and different compositions
• D. identical crystal form and identical composition

Hint:

Polymorphic minerals have the same chemical composition but crystallize in different forms, leading to varied properties.

Answer 1

The Correct Option is A

Step 1: Understanding Polymorphism.
Polymorphism occurs when a mineral can crystallize in different forms while maintaining the same chemical composition. Different crystal structures result in distinct physical properties.
Step 2: Analyzing the options.
(A) different crystal forms and identical composition: Correct — Polymorphic minerals can have different crystal forms but the same chemical composition.
(B) different crystal forms and different compositions: Incorrect — This describes a situation where minerals may be different species, not polymorphs.
(C) identical crystal form and different compositions: Incorrect — This would describe isomorphs, not polymorphs.
(D) identical crystal form and identical composition: Incorrect — This would describe a single mineral species, not polymorphism.
Step 3: Conclusion.
The correct answer is (A) different crystal forms and identical composition, which defines polymorphism in minerals.