Database of luminescent Minerals


Chemical Formula: CaSO4 2H2O

Familly: Sulfates

Status: IMA-GP

Crystal System: Monoclinic

Mineral for Display: Yes

Associated names (luminescent varieties, discredited names, synonymes etc.):  alabasterselenite


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

Long Waves Picture (365nm)

OL (365 nm). Col. G. Barmarin; Photo: G. Barmarin

Short Waves Pictures (254nm)

OC (254 nm). Col. G. Barmarin; Photo: G. Barmarin


Galerie de photos:


     To the gallery (15 images in the gallery)

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

UV Type Color Intensity Observation Frequency
Long Wave (365nm): Yellowish White Strong
Short Waves (254 nm): Bluish White Strong


Syn: selenite;
Sometimes presents a hourglass fluorescing figure in the center of monocrystals first observed in crystals from Wiesloch (Germany) in 1927 by H. Himmel but is now known from many other localities with occurrences of gypsum crystals in clay beds. (Himmel, H.(1927): Gips von Wiesloch(Baden). Centralblatt für Mineralogie, Abt. A (1927), 342-349)

Main Activator(s) and spectrum:

Most Common Activator: Organic impurities

Other activators:            (UO2)2+ (Uranyl ion) as impurities ,

Peaks in the spectrum (nm):

ST  : 440-630nm 

494nm, 510nm, 544nm, 601nm (Hourglass figure, Canada)

 UO22+ : 469, 486, 507, 530, 554nm (sample from Morrocco)

Col. G.Barmarin; Photo: G. Barmarin


  To the spectrum gallery (2 spectra in the gallery)

Comments on activators and spectra:

Typical uranyl spectrum when green luminescence is present.
Greenish-white and bluish fluorescence most probably due to organic impurities.

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.
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