Tourmaline colors

The color of tourmaline originates from the metal ions (Fe, Mn, Cr, V, Ti, Cu) in its structure. Colors come both from light absorption by the individual ions (eg, Fe²⁺ or Cr³⁺) and by light absorbed by interactions between ions (eg, Fe²⁺-Ti⁴⁺, Mn²⁺-Ti⁴⁺ or Fe²⁺-Fe³⁺ intervalence charge transfer [IVCT]).

Blue color is usually caused by Fe²⁺ but can also come from Cu²⁺ in rare Brazilian elbaites.
[Blue iron-containing elbaite from Pakistan.] [The spectrum of blue copper-containing elbaite from Paraiba State, Brazil. 

Green color comes from either Fe²⁺-Ti⁴⁺ IVCT together with Fe²⁺, or from either Cr³⁺ or V³⁺ alone, or in combination.
[Uvite from the Mogok region of Myanmar containing mostly V and some Cr]

Amber to orange-brown colors (often seen in dravites) come from Fe²⁺-Ti⁴⁺ alone.
[Dravite from Yinietharra, Western Austrailia, dominated by color derived from the Fe²⁺-Ti⁴⁺ interaction.]

Yellow to yellow-brown colors result from Mn²⁺-Ti⁴⁺ IVCT.
[Elbaite from the Hyakule Mine, Nepal, displaying colors from interactions with titanium with Mn²⁺-Ti⁴⁺ IVCT and Fe²⁺-Ti⁴⁺ IVCT in different zones].

A greenish yellow to yellow color is from Mn²⁺ plus Mn²⁺-Ti⁴⁺  IVCT. 
[Faceted 'canary tourmaline' from Zambia].  [Mn-elbaite spectrum].

Pink and red colors are from Mn³⁺. The color of pink manganese-containing tourmalines often is associated with exposure to ionizing radiation (such as from the decay of ⁴⁰K, a common  constituent of pegmatites).

Black tourmalines (schorls, etc.) are dark because of their high concentrations of iron, manganese and titanium. When they are ground very thin, they are usually blue or brownish-green. [60 cm cluster of schorl from the Czech Republic]. [schorl spectrum].

Many tourmalines owe their color to a mixture of metal ions. The great diversity of color in tourmalines is due the the variability in which these mixtures occur.
[A slice of tourmaline from the Himalaya Mine, San Diego County, California, showing different colors from different causes]

Images of Tourmaline Slices

For images of colorful tourmaline slices and more information about their color go to the section on tourmaline slices . 

Representative tourmaline spectra

Visible Spectra: polarizations: (a = incident light polarized perpendicular to c-axis; c = parallel to c-axis)

Blue, green, brown and black Fe-containing tourmalines

GRR 512 spectrum; Schorl, GRR 512, White Queen Mine, Pala, California, 0.010 mm thick. Black in mass, blue when very thin. Contains 13.5% "FeO" and 0.95% "MnO". Data Files: a; c ;

GRR 596 spectrum; Elbaite, GRR 596G, Afghanistan, 0.25 mm thick. Dark green crystal colored by Fe²⁺ and Ti⁴⁺ - Fe²⁺ interactions. Contains 4.32% "FeO", 1.67% "MnO" and 0.04% "TiO₂". Data Files: a  ; c  ;

GRR 787 spectrum; Dravite, GRR 787, Sweeney Canyon, Anza Borrego, California, USA, 0.10 mm thick. The black crystal that most people would call schorl is green when thin. The intense absorptions in the perpendicular to c direction at 730 and 1120 nm result from enhancement of Fe²⁺ bands caused by interactions with Fe³⁺. The intense absorption in the same direction near 430 nm is from Fe²⁺ - Ti⁴⁺ intervalence charge transfer. The crystal contains 6.93% "FeO", 0.05% "MnO" and 0.53% "TiO₂". Data Files: a 0K ; c 0K .

GRR 79 spectrum Foitite, GRR 794, Schindler Mine, California, USA, 0.048 mm thick. Black crystal, blue when thin. Data Files: a  ; c  .

S3 spectrum, Dravite, S3, Newry, Maine, USA.  Brown to green, complexly zoned.  Spectra from a green zone.  Contains Mg1.19 Fe1.16 Ti 0.04. Data files:  a 0K ; c 0K .

CIT 12683 spectrum, Dravite, CIT 12683, Yinnietharra, Australia. Brown crystal, 0.680 mm thick. The absorption band near 450 nm arising from Fe²⁺ - Ti⁴⁺ intervalence charge transfer is the primary cause of the color of this crystal. Data files:  a  ; c  .

GRR 2098 spectrum; Uvite, GRR 2098, Wata Poore area, Konar Province, Afghanistan. 3.98 mm thick. Pale brown crystal. The color is dominated by the Fe²⁺ - Ti⁴⁺ intervalance charge transfer arising from the minor amounts of both Fe and Ti that are in this crystal. Data Files: a 0K ; c 0K .

S 8 spectrum; Uvite, S 8, Pierrepont, New York, USA, NMNH 81511, 0.10 mm thick. Black crystal. Contains 8.23% "FeO" and 0.55% "TiO₂". Data Files: a 0K ; c 0K . 

GRR 244 spectrum; Uvite, Brumado, Bahia, Brazil. Plotted as 0.80 mm thick

GRR 1935a spectrum; Elbaite from Usakos, Namibia, blue crystal. 3.641 mm thick. Data Files: a  ; c  .

GRR 1935b spectrum; Elbaite from Usakos, Namibia, green crystal, 3.654 mm thick. Data Files: a  ; c  .

GRR 3770 spectrum;  a pure blue  crystal, unknown locality. 2.00 mm thick. Data Files: a  ; c  .

Blue Cap Elbaite

•  GRR 2648 spectrum, blue cap from the Tourmaline Queen Mine

Green V³⁺ and Cr³⁺ tourmalines

• GRR 2128 spectrum; green uvite with 0.049 wt% Cr₂O₃ and 0.614 wt% V₂O₃ from the Mogok region, Myanmar, plotted as 1 mm thick.
• GRR 2467 spectrum: yellow-green uvite with 0.140 wt% Cr₂O₃ and 0.044 wt% V₂O₃ from Tanzania, plotted as 1 mm thick.
• GRR 1719 spectrum: dark-green dravite with 0.199 wt% Cr₂O₃ and 0.452 wt% V₂O₃ from Tanzania, plotted as 1 mm thick.
• GRR 768 spectrum; dark-green fluor-rich uvite with 0.140 wt% Cr₂O₃ and 0.244 wt% V₂O₃  from Kenya, plotted as 1 mm thick.
• GRR 3245; Elbaite from Kisiwani village, Tanga Province, Tanzania, that shows Usambara effect, 0.404 mm thick. This is part of the sample used by Taran et al., (2015) Mineralogical Journal (Ukraine) p12-21. Data Files: a  ; c .
• Olenite spectrum; synthetic Cr-doped with 0.42 wt% Cr₂O₃ and no V₂O₃ plotted as 1 mm thick. Contributed data from Michael Taran, Kiev. See Taran et al (1993) Phys. Chem. Minerals 20: 209.

 Cu²⁺ colored tourmalines

Pink and yellow-green Mn-containing tourmalines

GRR 1368 spectrum; dark pink elbaite from Otjimbinque, Namibia. The color is from Mn³⁺ and represents one of the deeper colored natural pink tourmalines.

GRR 565 spectrum; light pink elbaite from the Himalaya Mine, Mesa Grande, California. The color  is natural color from Mn³⁺.

GRR 565 spectrum; dark pink elbaite from the Himalaya Mine, Mesa Grande, California. This sample has been irradiated with ⁶⁰Co gamma rays to enhance its color . The color is from Mn³⁺ and represents a typical treated color for pink tourmalines.

GRR 876 spectrum; heavily irradiated pink elbaite from the Stewart Mine, Pala, California. Although the sample has been treated, the color is from Mn³⁺ and resembles the color of natural pink tourmaline.

GRR 888 spectrum; darker red olenite   from Khammam, Andhra Pradesh, India. Andreas Ertl provided data on site occupancies: X site = [Na 0.7, Ca 0.0, [] 0.3]

GRR 757 spectrum; Yellow-green elbaite,  Zambia, 2.00 mm thick, with high Mn²⁺ content and some Ti⁴⁺ that interacts with the Mn²⁺. Ref: Rossman & Mattson (1986) Amer. Mineral 71, 599-602. Data Files: a 0K ; c 0K ;

Elbaite soectrum; Usakos, Namibia, pale yellow crystal, 5.353 mm thick. Data Files: a  ; c  .

GRR 1932 spectrum; Pale pink rossmanite, Rozná, Czech Republic, 2.976 mm thick. This is a crystal of the type specimen. The color comes from the radiation-induced Mn³⁺ content. Here is the NIR OH region; of the same crystal. Data Files: a 0K ; c 0K ;

Red tourmaline with Fe

• GRR 228 spectrum; Red dravite from Narok, Kenya, plotted for 0.10 mm thick. Same sample with expanded NIR range. Composition: Na_0.88Ca_0.01Mg_2.27Fe_0.58Mn_0.00T_i0.03Al_6.12(BO₃)₃Si_5.99O₁₈(OH)₄.  See: Physics and Chemistry of Minerals 14, 225–234. Data Files: a  ; c  .
• MT Red dravite spectrum; from Engusero Sambu, Tanzania, plotted for 1.00 mm thick. Same sample with expanded NIR range. The color comes from Fe²⁺-Fe³⁺ interactions. Composition: Na_0.66Ca_0.16Mg_2.62Fe_0.33Mn_0.02T_i0.02Al_5.95(BO₃)₃Si_6.04O₁₈(OH)₄. See: Physics and Chemistry of Minerals 42, 559-568. Data Files: a  ; c  . Contributed data from Michael Taran, Kiev.
  

Orange tourmaline

• GRR 1715 spectrum; orange dravite from Nigeria, plotted for 3.60 mm thick. The color  is dominated by an Fe²⁺-Ti⁴⁺ interaction. Data Files: perp c ;  c  .

Tourmaline with the Usambara Effect

• MT Tourmaline spectrum with the Usambara effect from northeastern Tanzania, (Na_0.72 Ca_0.25)_0.97(Mg_3.23 Al_5.66 Cr_0.12)_9.01B₃Si_5.94O₂₇(OH)_4.00, plotted for 1.00 mm thick. Same sample with expanded NIR range spectrum. At the thickness of about 0.2 mm this sample looks like a usual light-green tourmaline with a distinct dichroism. The Usambara effect in these tourmalines appears more or less distinctly at thicknesses of about 2 to 5 mm. To see it, one would decrease the thickness (grind and polish the sample) until it changes the color from red to green. Data Files: a  ; c . Contributed data from Michael Taran, Kiev; Mineralogical Magazine, DOI: 10.1180/minmag.2016.080.016

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

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