Metavivianite an intermediate mineral phase between vivianite, and ferro/ferristrunzite - a Raman spectroscopic study
Frost, Ray L.; Weier, Matt; Lyon, William G.
published: May 5, 2004
A comparison between the minerals vivianite, metavivianite, and ferro/ferristrunzite is made using Raman spectroscopy. The Raman spectrum of metavivianite is broad and more closely resembles the spectrum of ferro/ferristrunzite than vivianite. This is not unexpected since both minerals are triclinic. Metavivianite is characterised by a broad profile in the hydroxyl stretching region with bands observed at 3368 and 3133 cm-1. The width of the bands indicates the structure of metavivianite is disordered. In the PO stretching region bands are observed at 1123, 1060, 1005 and 958 cm-1 and are assigned to the stretching modes. Vivianites with partial oxidation are characterised by a sharp OH stretching band observed around 3480 cm-1 in the Raman spectrum. It is proposed that metavivianite is a transitional oxidation phase between the vivianite and the ferro/ferristrunzite end members.