Database of luminescent Minerals


alexandrite


Chemical Formula:See CHRYSOBERYL

Familly: Oxides and hydroxides

Status: NON APPR

Crystal System: Orthorhombic

Mineral for Display: No


Luminescence:


UV Type Main color Intensity Observation Frequency
Long Waves (365nm):      Red Weak
Mid waves (320 nm):      Red
Short Waves (254 nm):      Red Weak
Other colors LW:     
Greenish white ,
 

Phosphorescence (in the common meaning of the term) seen by naked eye:


No phosphorescence seen by naked eye whatever the type of UV

Comments:


CHRYSOBERYL var. alexandrite


Main Activator(s) and spectrum:


Most Common Activator: Cr3+

Other activators:            Mn4+ , V2+ ,

Peaks in the spectrum (nm):

663, 664,

Cr3+ II : 679, 680nm 

Cr3+: 689, 690, 693, 694nm

Cr3+701, 707, 720, 721nm 

Broad band peaking at +/- 600 

V2+ (?) : broad band peaking at +/- 717nm 

Mn4+ : broad bands around 650 - 670nm 


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

            ...

  To the spectrum gallery (5 spectra in the gallery)


Comments on activators and spectra:


Two types of Cr3+ luminescence centers have been found in natural alexandrite, characterized at 300 K by R-lines at approximately 679.0 with 677.3 nm and 694.4 with 691.7 nm, accompanied by very many N-lines of Cr-Cr pairs.

Those centers have been identified as connected with substitutions of Al3+ in different structural sites (Tarashchan 1978).  (Scalvi et al. 2003; Trindade et al. 2011)


Best Locality for luminescence(*):


(*)Data are not exhaustive and are limited to the most important localities for fluorescence


Bibliographical Reference for luminescence:



Luminescence Reference on internet:



Mineralogical Reference on internet:


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

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

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