Database of luminescent minerals 

BENITOITE

Chemical formula: BaTiSi₃O₉

Family: Silicates

Status: IMA-GP

Crystal system : Hexagonal

Display mineral: OUI

Luminescence:

Daylight picture

BENITOITE;
Photo and Copyright: James Hamblen
Site of the author
Used with permission of the author

Longwave (365nm) picture

BENITOITE, UVLW ;
Photo and Copyright: G. Barmarin

Shortwave (254nm) picture

BENITOITE;
UVSW
Photo and Copyright: James Hamblen
Site of the author
Used with permission of the author

Pictures Galery:

  
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Phosphorescence (in the common sense of the term) observable with the naked eye:

Activator(s) and spectrum:

Activator(s): TiO₆, Cr³⁺,  Fe³⁺,  Ti³⁺,  Ti⁴⁺,  Cu⁺,  Mn⁴⁺,  Ti - O,  

Peaks in the spectrum (nm):

TiO₆ : broad band at 419nm (due to the transition of ³T₁ → ¹A₁ in the TiO₆ octahedra)
Ti³⁺ : broad band around 650-660nm with half-width of +/-135nm 
Cr³⁺ : peak at 680nm
Mn⁴⁺ : large band at 720nm
Cu⁺? replacing Ba²⁺ and Ti³⁺?  (exc 337nm:(Gorobets)): 720nm
450nm (exc 254nm)

Spectrum: Michael Gaft, Petah Tikva, Israel. Plot: Institute of Mineralogy, University of Vienna, Austria, with permission of the authors.

Spectrum Galery:

  
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Comments on spectrum and activators:

Robbins cites Fe as activator for the red color and Ti for the blue; recent spectrographic studies give new data:
There are three broadbands:
- one around 419 nm (blue band) is connected with intrinsic luminescence centers, namely isolated TiO₆ octahedra,
- one at 650 nm (Yellow band) for Ti³⁺ ,
- one at 720 (half-width 125nm) for Mn⁴⁺
and a narrow line at 680 for Cr³⁺.(Gaft)

Manganese participation is supported by chemical analysis of benitoite (0.03 to 0.11%).

The metastable level ³T_1u is the emitting level at low temperatures with a long decay time of 1.1 ms. At higher temperatures an energy level with higher radiation probability must be involved in the emission process, and this level is situated at 0.06 eV higher than the lowest level. These two levels may be connected with ³T_1u level splitting or with closely spaced ³T_1u and ³T_2u levels.

Decay time shortening and thermal quenching are connected with nonradiative decay within the TiO₆ luminescence center, while energy migration does not take place at least up to room temperature.
(Source: M. Gaft, L. Nagli, G. Waychunas and D. Weiss, The nature of blue luminescence from natural benitoite, Physics and Chemistry of Minerals, vol31, 2004)

The red emission of benitoite consists of two individual bands and one line and suggest that the activators of luminescence in benitoite system are Ti³⁺ and a d3 element, namely Cr³⁺ or Mn⁴⁺.
(Source: M. Gaft, L. Nagli, G. Waychunas and G. Panczer, The nature of red luminescence of natural benitoite, Mineralogy and Petrology, Vol85, 2005)

Best localities for fluorescence (*):

• Benitoite Gem Mine, San Benito County, California, USA;
• Big Creek and Rush Creek junction, Fresno County, California, USA;
• Esquire #1 Claim, Rush Creek, Fresno County, California, USA;
• Victor Mine, San Benito County, California, USA;
• Kinzandani, Hashidate, Ohmi, Itoigawa City, Niigata Prefecture, Chubu Region, Honshu Island, Japan;

(*)The data are not exhaustive and are limited to a few remarkable localities for fluorescence

Bibliographic reference for luminescence:

• The Henkel Glossary of Fluorescent Minerals, Dr. Gerhard Henkel, Published by the FMS, 1989 ,
• Fluorescence: Gems and Minerals Under Ultraviolet Light, Manuel Robbins, 1994, Geoscience Press, ISBN 0-945005-13-X ,
• The World of Fluorescent Minerals, Stuart Schneider, Schiffer Publishing, 2006, ISBN 0-7643-2544-2 ,
• Luminescence Spectroscopy of Minerals and Materials, M. Gaft, R. Reisfeld, G. Panczer, Springer Editor, ISBN: 10 3-540-21918-8 ,
• Luminescent Spectra of Minerals, Boris S. Gorobets and Alexandre A. Rogojine, Moscow, 2002 ,

Reference for luminescence on the Internet:

Mineralogical reference on the Internet:

  http://www.mindat.org/show.php?name=Benitoite

  http://webmineral.com/data/Benitoite.shtml

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