Color and any change in color intensity on rotation of the stage.
Color is related to chemical composition.
Pleochroism is often diagnostic. Habit, Shape or Outline . Habit can be diagnostic for euhedral grains. The shape of weathered or worn grains may also provide information on their nature, source, mode of transport, or type of weathering regime. Size seldom gives information on the nature of themineral, but may be important for interpretations of origin, mode of transport, or changes inlithology.