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+
- Fe3+ intervalance charge transfer. These two
processes cause the
blue color of partially oxidized vivianite.
Image of a representative vivianite spectrum
-
Vivianite CIT 9976 spectrum;. 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;
-
Vivianite CIT 9976 spectrum;. 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;, perp b;
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revised 11-Jul-2022
