|Thin section of Piemontite from Laponia,
Sweden. The 4 micrographs below illustrate the beautiful pleochroism of
Piemontite, an epidote containing Mn3+, from yellow to pink,
red and brown.
In the spectra at the bottom of this page, the 3 peaks
in the visible region originate from the crystal fields transitions of
Mn3+ in distorted octahedral site.
The red curve is α spectrum (yellow
crystals) and the blue curve is β spectrum.
The small forbidden transitions superimposed to
the main peaks could be due to Fe3+.