Kyanite spectra

Kyanite Visible Spectra (300 - 1500 nm)

The blue color of metamorphic kyanite comes from the Fe²⁺ - Ti⁴⁺ intervalence interaction. Deep blue crystals have larger amounts of the Fe²⁺ - Ti⁴⁺ intervalence interaction. Yellow green color comes from Fe³⁺. Sky blue kyanite found in diamond pipes such as the Roberts Victor Mine in South Africa contains Cr³⁺. Rare examples of iron-containing orange kyanite are found.

Kyanite dominated by intervalence absorption

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.
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 color is from the intervalence interactions. Sharp features near 380 and 430 nm are from from Fe³⁺ as is the broad band 1020 nm.

Chromium-containing kyanite

GRR 434 spectrum, 6K; from Reitfontein Pipe, South Africa. Plotted as 1.0 mm thick. The color of this material comes from its Cr³⁺ content. Data Files: alpha 6K; beta 9K; gamma 9K;
GRR 1692 spectrum, 6K; from Kenya. This is a blue, 0.735 mm thick cleavage slab. The color is from both Fe³⁺ and Cr³⁺.

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