Final answer:
A mineral's luster is determined by the interaction of light waves with the electrons in the mineral, affected by the particle nature of light and factors such as the mineral's surface electrons.
Step-by-step explanation:
A mineral's luster depends on the way in which light waves interact with the electrons of the elements in the mineral. Luster can be metallic, where minerals do not allow light to pass through the atomic structure, or non-metallic, where some light can pass through. Color in minerals often comes from impurities, and might not be diagnostic, while the streak of a mineral, which is the color in powdered form, can be more indicative of true color for metallic minerals. Understanding the particle nature of light is crucial, as phenomena like the photoelectric effect show that light can eject electrons from metal surfaces, influencing luster perceivable to the eye.