Vivianite Visible Spectra (300 - 1800 nm)
The iron phosphate mineral, vivianite, is unusual in that, when ground,
the green mineral will turn dark blue due to partial oxidation.
The origin of color in vivianite is iron. In this structure,
most of the iron is Fe2+ which causes the green color seen in many specimens.
If some of the iron is
Fe3+ it will interact with the Fe2+ to both increase the
intensity of the Fe2+ absorption and to cause Fe2+ -
Fe2+ intervalance charge transfer. These two processes cause the
blue color of partially oxidized vivianite.
Image of a representative vivianite spectrum
- Vivianite CIT 9979 spectrum, 7K;.
Pale blue vivianite from Mullica Hill, New Jersey, with Fe2+ bands near
820 and 1220 nm. Plotted for 0.10 mm thickness.
Data Files: b, 3K;
- Vivianite CIT 9979 spectrum, 7K;.
Dark blue vivianite from Mullica Hill, New Jersey. In this spectrum, the
intervalance charge transfer gives rise to a band in the 680 nm region for light polarized
parallel to the b-axis. 0.02 mm thickness.
Data Files: b, 25K;, perp b, 256;
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