Final answer:
To appear shiny, a material must be able to reflect light in a specific way. Metallic minerals have a metallic luster because they do not allow light to pass through their atomic structure. Non-metallic minerals have a non-metallic luster because they allow some light to pass through.
Step-by-step explanation:
To appear shiny, a material must have the ability to reflect light from its surface in a regular pattern. When light hits a material, it can be reflected, absorbed, or transmitted. The shine or luster of a material is determined by how it reflects light. Reflection happens when light bounces off a material, which can occur differently depending on whether the surface is polished or rough.
Materials with a smooth surface reflect light in a specific direction, which gives them a shiny appearance. These include polished metals or mirrors. On the other hand, materials with rough surfaces, like paper or fabric, diffuse the light in many directions, resulting in a lack of shine. For a material to have a metallic luster, it must not allow light to pass through its atomic structure, while non-metallic materials might allow some light transmission but can still appear shiny if the surface is smooth enough.
Therefore, to ensure a material appears shiny, it must have a smooth surface that can reflect light neatly in a consistent direction as broadly illustrated by the Law of Reflection. Surfaces like metals that are malleable and ductile, resist corrosion, and conduct heat and electricity well tend to have this smooth, reflective property, contributing to their lustrous appearance.