Dumortierite Visible Spectra (350 - 1000 nm)
Dumortierite is commonly either blue or pinkish-lavender (or a color
derived
from a mixture of these two colors. The color of dumortierite is
usually
due to its iron and titanium content. Although the exact origin of
color
is still under investigation, we think that charge
transfer between Fe2+ and Ti4+
causes the 500 nm band and think that the 600 nm band arises from Fe2+
- Fe3+ intervalence charge transfer.
Images of representative dumortierite spectra
-
GRR 122
spectrum; 0.103 mm thick lavender
dumortierite sample from Dehesa, San Diego County,
California,
USA, with mostly the 500 nm band. Data Files: perpendicular to c;
parallel
to c;
-
GRR 347
spectrum; 0.066 mm thick blue durmortierite
sample from Sahirina, Madagascar, with the 600 nm band dominant. Data
Files:
perpendicular
to c; parallel
to c;
- GRR
1921 spectrum;
0.030 mm thick dumortierite from Almgiotheii,
Rogaland,
Norway, with both the 500 and 600 nm bands. Data Files: perpendicular to c;
parallel
to c;
- GRR
1966 spectrum;
0.081 mm thick deep
pink dumortierite from Margarite Peak, near
Fallbrook, California, USA, with the 500 nm band
dominant. Data Files: perpendicular to c;
parallel
to c;
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revised
26-Oct-2023