Absorption spectra of the manganese-bearing chain silicates pyroxmangite, rhodonite, bustamite and serandite

The optical absorption spectra of pyroxmangite, rhodonite and serandite show that the pink colors are due primarily to octahedrally-bonded Mn(II). The brown color of bustamite can be attributed to octahedrally-bonded Mn(II) bands superimposed on a strong background absorption. Pyroxmangite has forbidden bands in the visible region due to Fe(II) in octahedral sites. All four silicates have bands in the infrared characteristic of Fe(II) in octahedral sites, while pyroxmangite, bustamite, and serandite also show tetrahedrally-bonded Fe(II) bands.