Spinel Group Visible Spectra (generally 350 - 2500 nm)

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

• Black spinel H-3378, from Matsaingo, Madagascar. 0.257 mm thick. Data File.
• Black spinel CIT-6846, from Eshiva, Madagascar. 0.420 mm thick. Data File.
  

Gahnite, ZnAl₂O₄

• Blue gahnite, locality unknown. The color is from Fe²⁺. data file
• Blue gahnite, GRR 5441, Brazil,       plotted as 0.518 mm.  Data file with composition.

• 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.

Link to an extensive collection of references to mostly color and visible spectroscopy of spinels

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