These are spectra of the variety tanzanite
which is colored by
vandadium
Image of the zoisite absorption spectrum
GRR 1265
spectrum, 4K; from Tanzania,
normalized to 3.0 mm thick. The color of this material varies
considerably
with the direction in which it is observed. It varies from greenish
yellow
to deep blue to red-violet. Data Files: E||a=gamma
6K;E||b=alpha 9K;E||c=beta 9K;
Literature
data from Faye and Nickel (1971) showing the spectrum of a
tan colored zoisite (Tanzanite) before and after heating to
600°C
