what is pleochroism and its importance in mineralogy ?

Answer 1

Pleochroism is an optical phenomenon in which grains of a rock appear to be different colors when observed at different angles,under a petrographic microscope.

Pleochroism does play an important roll in mineralogy.

Pleochorism is caused by the double refraction of light by a colored gem or crystal. Light of different polarizations is bent different amounts by the crystal, and therefore follows different paths through the crystal. The components of a divided light beam follow different paths within the stone and travel at different speeds, and each path will absorb different colors of light. When the stone is observed at some angle, light following some combination of paths and polarizations will be present, each of which will have had light of different colors absorbed. At another angle, the light passing through the stone will be composed of another combination of light paths and polarizations, each with their own color. The light passing through the stone will therefore have different colors when it is viewed from different angles, making the stone seem to be of different colors.

Answer 2

:the property of certain crystals of exhibiting different colors when viewed from different directions under transmitted light.