Spinel Group Visible Spectra (generally 350 - 2500 nm)
The spinels are a diverse group of minerals with wide
variation in their chemical composition. Among the more common
spinel group minerals, the color is due to chromium and iron.
Rarely, cobalt will be a cause of color.
Natural MgAl2O4 Spinels
- Red
Cr-spinel, JQ-13, Sri Lanka. Visible Region only, plotted as 1.50 mm thick. The color comes from Cr3+.
data file
- Blue
cobaltian spinel, Yakutia kimberlite pipe, Russia.
Approximately 0.05 mm thick. The color comes from Co2+
in the tetrahedral site. Contributed data from Michail N.
Taran, Kiev: data
file. Picture of
the crystal and the area of measurement.
- Blue cobaltian spinel, Samos
Island, Greece. Plotted normalized to 10.0 mm thickness. The color
comes from Co2+ in the tetrahedral site. Contributed
data from Michail N. Taran, Kiev: data file.
- Blue cobaltian
spinel, GRR 2381, Baffin Island, Nanavut, Canada. The blue color of the
crystals comes from Co2+ in the
tetrahedral site. 0.849 mm thick. data
file
- Blue cobaltian spinel, GRR 3017, from Viet Nam. . Plotted as 1.435 mm. Data file.
- Pale blue spinel GRR 2224, from Vietnam. Plotted at 2.986 mm. Data File
- Pale lavendar spinel. JQ-7, Plotted at 0.711 mm. Data file; Composition file.
- RDS-153c
Pink spinel from Tanzania containing both Cr3+
and Fe2+. Here we see the near-infrared region
showing the absorption bands from Fe2+ in the
tetrahedral site. 0.503 mm thick; 1.028% FeO. Sample Sp3 of Shannon
& Rossman (1991) J Phys Chem Solids 52, 1055. data
file
Black Spinel Crystals
Gahnite, ZnAl2O4
- Green gahnite, GRR 2903, Pedras Bonitas Pegmatite, Rio Grande do Sul, Brazil. Plotted at 0.420 mm thick. Data File.
Synthetic Spinel-group materials
- MgAl2O4:Cr
spinel, synthesized by the flux method in Novosibirsk,
Russia. Normalized to 10.0 cm. Colored by Cr3+.
Data File: Contributed data from Anton Vasiliev, LAL, Moscow:
Spinel_Red,
25 K.
- MgAl2O4:Co
spinel, synthesized by the flux method in Novosibirsk,
Russia. Normalized to 10.0 cm. Colored by Co2+.
Data File: Contributed data from Anton Vasiliev, LAL, Moscow:
Spinel_blue,
25 K.
High pressure spinel polymorphs of olivine compositions
- γ-Ni2SiO4
Spinel, GRR 435 synthesized by Syuniti Akimoto.
- γ-Ni2SiO4
Spinel, published in Rossano et al. European Journal of
Mineralogy 1996:8, 471-475. Data file: Contributed data from
Stephanie Rossano, Paris: data file, 15 K.
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