Luster is a word used to describe the light-reflecting characteristics of a mineral specimen. The luster of a specimen is usually communicated in a single word. This word describes the general appearance of the specimen’s surface in reflected light.

Eleven adjectives are commonly used to describe mineral luster. They are: metallic, submetallic, nonmetallic, vitreous, dull, greasy, pearly, resinous, silky, waxy, and adamantine. These adjectives convey – in a single word – a property that can be important in the identification of a mineral.

The luster of a material can also determine how it will be used in industry. For example, jewelry manufacturers would not be the top consumer of gold if the metal had an unattractive luster. The pearly luster of muscovite makes ground muscovite a common ingredient in cosmetics.