Database of luminescent Minerals


DOUBTFULL FLUORESCENCE but cited by some authors

Chemical Formula: (K,Ba,Ca)2(UO2)2Si5O13 H2O

Familly: Silicates

Status: IMA-GP

Crystal System: Orthorhombic

Mineral for Display: No


UV Type Main color Intensity Observation Frequency
Long Waves (365nm):      Yellowish Green Very weak
Mid waves (320 nm):      Yellowish Green Weak
Short Waves (254 nm):      Yellowish Green Weak

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

No Data


Usually cited as non-fluorescent in the litterature despite pictures and samples in collection; identification to be verified; Fluorescent Hyalite can cover weeksite xls or xls can be included in strong fluorescent chalcedony making difficult to say in some samples if weeksite does fluoresce by itself or not (see sample from Thomas range Mountains, USA on Mindat)


A crystallized sample corresponding to the facies of the weeksite and labelled as such from the Anderson Mine clearly shows a low fluorescence from the crystals themselves (no visible hyalite coating) and a spectrum could even be taken.


Yellowish green fluorescence: RGB: 175, 255, 30 (approximatively calculated from the spectrum)

Main Activator(s) and spectrum:

Most Common Activator: (UO2)2+ (Uranyl ion) intrinsic

Peaks in the spectrum (nm):

UO22+: 532, 550nm (LW),  511, 531, 553nm (SW)

Col. G. Barmarin; Spectre: G. Barmarin


  To the spectrum gallery (2 spectra in the gallery)

Comments on activators and spectra:

The peaks of the spectrum are not very well defined but there is clearly  a peak around 532nm and a second one at 550nm. Other peaks should be found after deconvolution of the spectrum but are only slightly visible as shoulders in the curve. 

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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