As can be seen on preceding pages, a lot of glaucophane
crystals are corroded and altered to another green amphibole. In some
parts of the section, only altered material is visible as in the figures
shown here. The 2 micrographs were obtained with different orientation of
the polarizer. Some crystal area are still pleochroic (blue-green to
green), some others are not.
Spectrum of a pleochroic green to blue-green region.
Observe the movement of the charge-transfer absorption band to the
lower energies compared to glaucophane.
Spectrum of a non pleochroic green region with rotation of
polarizer by 90°. Absorption band is now beyond 700 nm.