Why are crystals shiny?

Crystals are shiny due to their smooth, flat surfaces that reflect light effectively. The arrangement of their internal atoms creates a regular lattice structure, which enhances their ability to reflect and refract light. Additionally, the specific mineral composition and the angle at which light hits the crystal can contribute to its luster, making some crystals appear more brilliant than others. This optical property is what gives many crystals their appealing, shiny appearance.