Sillimanite Visible Spectra (generally 350 - 1200 nm)
Images of representative sillimanite, Al2SiO5
Visible Spectra: polarizations: (a = alpha direction; b = beta direction; g = gamma direction)
Fe3+ is usually responsible for the yellow color in sillimanite. Chromium 3+ can contribute to the spectrum. Other colors can occur
when intervalence charge transfer is involved.
- GRR 273 spectrum;
sillimanite, Reinbolt Hills, Antactrica, NMNH 247011. Plotted as 5.0 mm thick with a
typical yellow color from Fe3+. Data Files:
- GRR 380 spectrum; sillimanite, Benson Mines, NY, NMNH 115586. Plotted as 0.40 mm thick.
- GRR 382 spectrum; sillimanite, Sardinia, plotted as 0.50 mm thick. Purple-brown
color from Fe3+ and intervalance charge transfer
presumed to be from Fe2+ and Ti4+.
a 3K ;
b 1K ;
- GRR 383 spectrum; sillimanite, Gilford, CT - Harvard collection 85919. Plotted as 0.60 mm thick. A brown sillimanite.
- GRR 386 spectrum; sillimanite, Norwich, CT, Harvard collection 85918. Plotted as 0.50 mm thick. A brown sillimanite.
- GRR 444 spectrum; sillimanite, Ceylon, Brittish Museum 1945,39. Plotted as 10.0 mm thick. The blue color comes from
intervalance charge transfer.
a 3K ;
- GRR 518 spectrum; sillimanite, Forfinger Point, Enderbyland, Antarctica, with chromium features in the spectrum. Ploted as 3.0 mm thick.
to the list of minerals
to the Index of Data Files
Mineral Spectroscopy home page