||Section in Diopside macro crystal (origin Brazil). Some
regions are colorless, they contain only Mg2+ and Fe2+.
Some other places are green colored, they contain also Cr3+
Spectra recorded on the green spots of the section are
characteristic of Cr3+ : two absorption bands are present in
the visible range: one between 600 and 700 nm and one around 400 nm. The
band in the NIR around 1050 nm is due to crystal field transition in Fe2+
ions. This iron band is mainly developed in colorless regions.