Luster describes?

• A. The quality and intensity of light reflected off the mineral.
• B. The color of the mineral's powder.
• C. The mineral's density.
• D. The mineral's magnetism.

Answer: (A)

Luster describes how a mineral's surface reflects light, i.e., how shiny it looks. This depends on how the surface interacts with light and helps distinguish metals from non-metals, with categories like metallic, glassy, pearly, silky, and dull. It’s not about the color of the powder (streak), nor about density (how heavy it is for its size) or magnetism (whether it is attracted to a magnet). So the quality and intensity of light reflected off the surface is the property being described by luster.