Database of luminescent minerals 

alexandrite

Chemical formula: See CHRYSOBERYL

Family: Oxides and hydroxides

Status: NON APPR

Crystal system : Orthorhombic

Display mineral: NON

Luminescence:

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

No phosphorescence visible to the naked eye under any type of UV

Comments:

CHRYSOBERYL var. alexandrite

Activator(s) and spectrum:

Activator(s): Cr³⁺, Mn⁴⁺,  V²⁺,  

Peaks in the spectrum (nm):

663, 664,

Cr³⁺ II : 679, 680nm 

Cr³⁺ I : 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.

Spectrum Galery:

  
  Go to the galery (7 spectra)

Comments on spectrum and activators:

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 localities for fluorescence (*):

• Magara Mine, Manyara Lake, Arusha Region, Tanzania ;
• Izumrudnye Kopi area, Malyshevo, Ekaterinburg, Sverdlovskaya Oblast, Middle Urals, Urals Region, Russia ;

(*)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 ,
• Luminescence Spectroscopy of Minerals and Materials, M. Gaft, R. Reisfeld, G. Panczer, Springer Editor, ISBN: 10 3-540-21918-8 ,

Reference for luminescence on the Internet:

Mineralogical reference on the Internet:

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

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

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