Which term refers to the arrangement of atoms that creates symmetry and internal organization in a mineral?

• A. Crystal Axes
• B. Crystal Planes
• C. Crystal Structure (lattice)
• D. Crystalline

Answer: (C)

The arrangement of atoms that creates symmetry and internal organization in a mineral is described by its crystal structure (the lattice). This term captures how atoms repeat in a three-dimensional pattern, forming a defined unit cell that stacks in space to produce the mineral’s overall symmetry and internal order.

Crystal axes are the directions used to describe the lattice’s geometry, not the arrangement itself. Crystal planes are the sheets cutting through the lattice that relate to Miller indices; they describe surfaces within the structure but don’t define the entire repeating arrangement. Crystalline is an adjective describing a mineral that has such an ordered lattice, rather than naming the arrangement itself. Thus, crystal structure (lattice) is the best term because it explicitly refers to the organized, repeating atomic pattern that gives rise to symmetry.