Database of luminescent Minerals


Chemical Formula: Zn2SiO4

Familly: Silicates

Status: IMA-GP

Crystal System: Hexagonal

Mineral for Display: Yes

Associated names (luminescent varieties, discredited names, synonymes etc.):  troostitebeta-willemite


UV Type Main color Intensity Observation Frequency
Long Waves (365nm):      Green MediumRarely
Mid waves (320 nm):      Green Strong
Short Waves (254 nm):      Green Very StrongOften

Daylight Picture

WILLEMITE, Franklin, New Jersey, USA;
Photo and Copyright: James Hamblen
Site of the author
Used with permission of the author

Short Waves Pictures (254nm)

WILLEMITE under UVSW, Franklin, New Jersey, USA;
Photo and Copyright: James Hamblen
Site of the author
Used with permission of the author


Galerie de photos:


     To the gallery (14 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): Green StrongOften
Short Waves (254 nm): Green Very StrongOften

Thermoluminescence: Yes


Variété troostite : willémite manganèsifère ;
beta-willemite nom erroné appliqué a une variété trouvée à Franklin-Sterling Hill et fluorescente en jaune ;
Certains échantillons de Brandtite fluorescents en vert OC devraient leur fluorescence à la willemite associée ;

Prior to the development of halophosphor in 1942, the first generation of phosphor used in fluorescent tube was  synthetic willemite activated with manganese-II. 

Main Activator(s) and spectrum:

Most Common Activator: Mn2+

Peaks in the spectrum (nm):

Mn2+ replacing Zn2+ : broad band peaking at +/- 525nm 

Spectrum: Michael Gaft, Petah Tikva, Israel. Plot: Institute of Mineralogy, University of Vienna, Austria, with permission of the authors.

Comments on activators and spectra:

Lifetime: 400μs @520nm

The action of ultra-violet rays on a large series of minerals of all kinds was tested by G. F. Kunz and C. Baskerville in 1903, and by E. Engelhardt in 1912. T. Liebisch in 1912 determined spectroscopically the nature of the green fluorescence from willemite. W.S. Andrews has pointed out in 1922 that artificially prepared willemite is only active when it contains some manganese, the shade of the green fluorescence depending on the amount of manganese present. Palache (1928) confirmed that the willemite containing manganese fluoresces the strongest.

Dake (1941) stated that most connoisseurs of fluorescent minerals agree that willemite from Franklin an Ogdensburg, N.J. is the most spectacular of all luminescent minerals.


Best Locality for luminescence(*):

(*)Data are not exhaustive and are limited to the most important localities for fluorescence

Bibliographical Reference for luminescence:

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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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