Why is color commonly unreliable property for identifying minerals?

Answer 1

Although most people think of color as an important characteristic of a specimen, it is not very useful in identifying a mineral.

• color is one of the physical properties most commonly used to describe minerals,

  but it is not a very good property to use to identify minerals

• some minerals are nearly always the same color like azurite (blue) and sulfur (yellow)
• many minerals come in a variety of colors - the changes are caused by

  slight chemical impurities or through exposure to heat

• color can change when the surface is exposed to moisture & air - it tarnishes or oxidizes
• some minerals have common names (varietal names) that describe a specimen

  with a certain color

  eg. Quartz - rock crystal (colorless), smoky quartz (brown), citrine (yellow), amethyst (violet),

  rose quartz (pink)

• color can be described as metallic or non-metallic and is often described along with

  luster though they are 2 different characteristics

• rocks are often distinctive or named because of a certain color which occurs because of

  their mineral content