Kyanite Visible Spectra (300 - 1500 nm)
The blue color of metamorphic kyanite comes from both the Fe2+ -
Ti4+ and Fe2+-
Fe3+ intervalence interactions. Deep blue crystals have larger amounts of the Fe2+ -
Ti4+ intervalence interaction. The green color of kyanite from Dodoma, Tanzania comes from
Fe3+. Both ferric iron green and a zone of blue intervanance charge transfer occurs in kyanite from Minas Gerais, Brazil. Sky blue kyanite found in diamond pipes such as the Roberts Victor Mine in South Africa contains Cr3+. Rare examples of Mn3+-containing orange kyanite are found in Loliondo, Tanzania..
Kyanite dominated by intervalence absorption
- GRR 285 spectrum;
from Minas Gerais, Brazil. This is the deep blue center of a 4.218 mm thick
cleavage slab. The body of the sample is yellow-green (from Fe3+)
and the typical blue streak is superimposed in the center of the crystal.
The blue color is from the intervalence interactions. Sharp features near 380
and 430 nm are from from Fe3+ as is the broad band 1020 nm.
- HVD105650 spectrum ; from
Itabira, Minas Gerais, Brazil. This is the deep blue center of a 1.05 mm
thick cleavage slab. The color is from the intervalence interactions. Weak
features from Fe3+ occur at about 380 nm.
- MT Yakutia: from Yakutia (now
Sakha Republic), Russia. This is a blue crystal plotted as 1.0 mm
thick. In the spectrum of this crystal, the band in the 800 nm region
(Fe2+ - Fe3+ intervalence charge transfer) is nearly as strong as the Fe2+ -
Ti4+ band in the 620 nm region. Contributed data from Michail Taran, Kyiv, Ukraine. Data files: E\\a, E\\c.
GRR 343 spectrum; from Reitfontein
Pipe, South Africa. Plotted as 1.0 mm thick. The color of this material
comes from its Cr3+ content. Data Files: alpha; beta; gamma;
GRR 1692 spectrum; from
Kenya. This is a blue, 0.735 mm thick cleavage slab. The color is from
both Fe3+ and Cr3+.
Orange manganase-containing kyanite
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last updated 17-Nov-2011