Database of luminescent Minerals


ORTHOCLASE


Chemical Formula: KAlSi3O8

Familly: Silicates

Status: IMA-GP

Mineral for Display: No

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

Luminescence:


UV Type Main color Intensity Observation Frequency
Long Waves (365nm):      Yellowish White
Short Waves (254 nm):      Red
 

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


No Data

Thermoluminescence: Yes


Comments:


Adularia: SW and LW: Pink, violet, red, greenish, whitish.
Moonstone : SW: orange, red; SW: blue .


Main Activator(s) and spectrum:


Most Common Activator: Fe3+

Peaks in the spectrum (nm):

Fe3+ repl. Al3+ or Si4+ : band peaking at 700nm 

No spectrum for the moment

Comments on activators and spectra:


Polarized optical absorption spectra and laser-excited luminescence spectra have been measured on single-crystal Fe-rich orthoclase. The absorption spectrum consists of a series of sharp, weak bands that can be assigned to spin-forbidden crystal-field transitions of Fe3+ substituted on the tetrahedral Al3+ site of the feldspar structure. A broad-band luminescence in the deep-red region is the Stokes-shifted 4T1 -> 6T1, transition of tetrahedral Fe3+ and confirms the assignments to the absorption spectrum. The temperature dependence of the luminescence intensity can be accounted for by a phonon-assisted nonradiative decay proces.
(Absorption and luminescence of Fe3+ in single-crystal orthoclase, William B. White 1986 - see link below)
Time-resolved luminescence spectra of natural and synthetic hydrous volcanic glasses with different colors and different Fe, Mn, and H2O content were measured, and the implications for the glass structure are discussed. Three luminescence ranges are observed at about 380–460, 500–560, and 700–760 nm. The very short-living (lifetimes less than 40 ns) blue band (380–460 nm) is most probably due to the 4T2(4D) →6A1(6S) and 4A1(4G) →6A1(6S) ligand field transitions of Fe3+. The green luminescence (500–560 nm) arises from the Mn2+ transition 4T1(4G) →6A1(6S). It shows weak vibronic structure, short lifetimes less than 250 μs, and indicates that Mn2+ is tetrahedrally coordinated, occupying sites with similar distortions and ion–oxygen interactions in all samples studied. The red luminescence (700–760 nm) arising from the 4T1(4G) →6A1(6S) transition of Fe3+ has much longer lifetimes of the order of several ms, and indicates that ferric iron is also mainly tetrahedrally coordinated. Increasing the total water content of the glasses leads to quenching of the red luminescence and decrease of the distortions of the Fe3+ polyhedra.

 

Cathodoluminescence: faint red.


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:


  http://www.mindat.org/show.php?name=Orthoclase

  http://webmineral.com/data/Orthoclase.shtml

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