Abstract
Optical absorption spectra are presented for taramellite, traskite and neptunite, all of which have both Fe2+ and Ti4+ as major elements. The spectra of each of these minerals are dominated by a single, intense absorption band in the 415 to 460 nm region with 7000 to 9000 cm−1 halfwidth. These transitions, assigned to Fe2+-Ti4+ intervalence charge transfer, showed little difference in intensity at 80 and 300 K and have molar absorptivities which range from ∼100 to ∼1300 M−1 cm−1. The Fe2+-Ti4+ absorptions in these standards generally compare well to other mineral spectra in which Fe2+ — Ti4+ intervalence absorption has previously been proposed with the exception of the most cited example, blue corundum.
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Mattson, S.M., Rossman, G.R. Fe2+-Ti4+ charge transfer in stoichiometric Fe2+,Ti4+-minerals. Phys Chem Minerals 16, 78–82 (1988). https://doi.org/10.1007/BF00201333
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DOI: https://doi.org/10.1007/BF00201333