Database of luminescent Minerals


Chemical Formula: Al2SiO4(F,OH)2

Familly: Silicates

Status: IMA-GP

Crystal System: Orthorhombic

Mineral for Display: No


UV Type Main color Intensity Observation Frequency
Long Waves (365nm):      Orange
Short Waves (254 nm):      Yellow
Other colors LW:          
Yellow , Orangy yellow ,
Other colors SW:               
Yellowish White , Pale Yellow , Greenish white ,

Daylight Picture


Photo and Copyright: Bill Barr
Used with permission of the author;

Short Waves Pictures (254nm)


Photo and Copyright: Bill Barr
Used with permission of the author;


Galerie de photos:


     To the gallery (2 images in the gallery)

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

No phosphorescence seen by naked eye whatever the type of UV

Thermoluminescence: Yes

Main Activator(s) and spectrum:

Most Common Activator: TiO6

Other activators:            Cr3+ ,

Peaks in the spectrum (nm):

TiO: broad band peaking at 455nm 

Cr3+ : lines at 680, 684, 695 - 697, 711, 734nm 

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)

Comments on activators and spectra:

Broad band peaking at 455 nm (TiO6). lines at 680, 684, 695-697, 711, 734 and band peaking near 680 nm, both due to Cr3+


It is established by Tarashchan that all photoluminescence characteristics of variously colored topazes from Ouro Preto, Brazil are due to three structurally non-equivalent Cr3+ centers isomorphically substituting Al3+ in the topaz structure and forming [CrO4F2]7−, [CrO4OH,F]7−, and [CrO4(OH)2]7− complexes. (Source: Luminescence spectroscopic study of Cr3+ in Brazilian topazes from Ouro Preto by A. N. Tarashchan and Al. see below).


Laser-induced time-resolved technique enables to detect three different Cr3+ and possibly Mn4+ and (TiO4) emission centers (Gaft et al. 2003a) 

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:

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