WHAT IS LUSTER?

Luster is a description of the way light enteracts with the surface of a crystal. This is how you would tell someone how a mineral looks. It has nothing to do with color or shape, but is related to transparency , surface conditions, crystal habit and index of refraction . The terms used are generally not scientific, but are meant to be descriptive. Most are self explanatory. The list below includes the most commonly used terms, however other unique terms are sometimes used for unique minerals or specimens.

Adamantine - very gemmy crystals
Dull - just a non-reflective surface of any kind
Earthy - the look of dirt or dried mud
Fiberous - the look of fibers
Greasy - the look of grease
Gumdrop - the look a sucked on hard candy
Metallic - the look of metals
Pearly - the look of a pearl
Pitchy - the look of tar
Resinous - the look of resins such as dried glue or chewing gum
Silky - the look of silk, similar to fiberous but more compact
Submetallic - a poor metallic luster, opaque but reflecting little light
Vitreous - the most common luster, it simply means the look of glass
Waxy - the look of wax