Chemical Formula: BaTiSi3O9
Familly: Silicates
Status: IMA-GP
Crystal System: Hexagonal
Mineral for Display: Yes
UV Type | Main color | Intensity | Observation Frequency |
---|---|---|---|
Long Waves (365nm): | Red | Weak | Rarely | Short Waves (254 nm): | Bluish White | Very Strong | Always |
Daylight Picture
BENITOITE;
Photo and Copyright: G. Barmarin
Long Waves Picture (365nm)
BENITOITE, UVLW ;
Photo and Copyright: G. Barmarin
Short Waves Pictures (254nm)
BENITOITE, UVSW ;
Photo and Copyright: G. Barmarin
Galerie de photos:
...To the gallery (20 images in the gallery)
UV Type | Color | Intensity | Observation Frequency |
---|---|---|---|
Long Wave (365nm): | None by naked eye | Short Waves (254 nm): | None by naked eye |
Most Common Activator: TiO6
Other activators: Cr3+ , Fe3+ , Ti3+ , Ti4+ , Cu+ , Mn4+ , Ti - O ,
Peaks in the spectrum (nm):
TiO6 : broad band at 419nm
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.
To the spectrum gallery (2 spectra in the gallery)
Robbins cites Fe as activator for the red color and Ti for the blue; recent spectrographic studies give new data: 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.
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 3T1u 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 3T1u level splitting or with closely spaced 3T1u and 3T2u levels.
(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)
(*)Data are not exhaustive and are limited to the most important localities for fluorescence
http://www.mindat.org/show.php?name=Benitoite
http://webmineral.com/data/Benitoite.shtml
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