Which term describes the characteristic crystal shape of a specific material?

Which term describes the characteristic crystal shape of a specific material?

• A. Habit
• B. Grain lines
• C. Macle
• D. Twinned crystal

Answer: (A)

Habit is the term for the typical external shape a crystal tends to form under its usual growth conditions. It describes the overall silhouette you’d expect to see for that material, such as octahedral or tabular forms in diamonds. This is exactly what’s meant by the characteristic crystal shape of a material. A macle refers to a crystal formed by twinning, producing a paired or joined shape, while a twinned crystal is a crystal that has a twin relationship—specific interior rearrangements that alter shape but don’t define the general exterior habit. Grain lines are internal growth features and don’t determine the crystal’s overall silhouette. So habit is the best description of the characteristic crystal shape.

Habit is the term for the typical external shape a crystal tends to form under its usual growth conditions. It describes the overall silhouette you’d expect to see for that material, such as octahedral or tabular forms in diamonds. This is exactly what’s meant by the characteristic crystal shape of a material. A macle refers to a crystal formed by twinning, producing a paired or joined shape, while a twinned crystal is a crystal that has a twin relationship—specific interior rearrangements that alter shape but don’t define the general exterior habit. Grain lines are internal growth features and don’t determine the crystal’s overall silhouette. So habit is the best description of the characteristic crystal shape.