Which term describes a material made of crystals or having crystallinity?

Which term describes a material made of crystals or having crystallinity?

• A. Glassie
• B. Doubly Refractive (anisotropic)
• C. Crystal Systems
• D. Crystalline

Answer: (D)

Describing a material as crystalline means it has a crystalline structure—atoms arranged in a regular, repeating three-dimensional lattice. This long-range order is what crystallinity refers to and distinguishes crystalline solids from amorphous ones, like glass, where the arrangement is random. In gems, crystalline substances such as diamond or quartz show this ordered structure, which also gives rise to optical properties tied to their lattice. The term describing double refraction highlights an optical behavior common in crystals but doesn’t itself define whether a material is crystalline. Crystal Systems, meanwhile, classifies the lattice shapes but isn’t the descriptor for a material’s crystalline state. Therefore, crystalline is the correct term.

Describing a material as crystalline means it has a crystalline structure—atoms arranged in a regular, repeating three-dimensional lattice. This long-range order is what crystallinity refers to and distinguishes crystalline solids from amorphous ones, like glass, where the arrangement is random. In gems, crystalline substances such as diamond or quartz show this ordered structure, which also gives rise to optical properties tied to their lattice. The term describing double refraction highlights an optical behavior common in crystals but doesn’t itself define whether a material is crystalline. Crystal Systems, meanwhile, classifies the lattice shapes but isn’t the descriptor for a material’s crystalline state. Therefore, crystalline is the correct term.