Database of luminescent Minerals


Chemical Formula: SiO2 nH2O

Status: IMA-GP

Crystal System: Amorphous

Mineral for Display: Yes

Associated names (luminescent varieties, discredited names, synonymes etc.):  cacholonghyalitehydrophanequincite (quincyite)geyseritelussatite


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

Daylight Picture

OPALE, Nevada, USA;
Col. G. Barmarin; Photo: G. Barmarin

Long Waves Picture (365nm)

OPALE, Nevada, USA; LW (365 nm).
Col. G. Barmarin; Photo: G. Barmarin

Short Waves Pictures (254nm)

OPALE, Nevada, USA; SW (255 nm).
Col. G. Barmarin; Photo: G. Barmarin


Galerie de photos:


     To the gallery (13 images in the gallery)

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

UV Type Color Intensity Observation Frequency
Short Waves (254 nm): Greenish Yellow StrongRarely

Main Activator(s) and spectrum:

Most Common Activator: (UO2)2+ (Uranyl ion) as impurities

Peaks in the spectrum (nm):

UO22+ : 504nm, 524nm, 547nm, 569nm, 601nm (opale Nevada, USA)

Col. G. Barmarin; Spectre: G. Barmarin


  To the spectrum gallery (2 spectra in the gallery)

Comments on activators and spectra:

Green luminescence related to uranium impurities.
Georges O. Wild from Idar Oberstein in Germany found as early as 1947 that the greenish yellow fluorescence of opal from Virgin Valley, Nevada was due to uranium traces and being identical of the fluorescence of the synthetic gemstone Emerada (synthetic spinel).
Wild cites  a weak band  at 600 to 605nm, strong band at 570 to 578nm, strong band at 545 to 550nm, medium band at 522 to 527nm and weak band at 500 to 503nm.
Before Wild, DeMent has already studied the spectrum of opal s luminescence before Wild but not as precisely.

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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Note: While all due attention has been paid to the implementation of the database, it may contain errors and/or accidental omissions. By nature, the database will always be incomplete because science always evolves according to new analysis.
A request providing no result means only that no such reference exists in the database, but it does not mean that what you are looking for does not exist, just not to our knowledge. If you think you have found an error or omission, please let us know via the contact page being sure to cite the source of information.


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