CORUNDUM
Chemical Formula: Al2O3
Familly: Oxides and hydroxides
Status: IMA-GP
Crystal System: Rhomboedric
Mineral for Display: Yes
Associated names (luminescent varieties, discredited names, synonymes etc.):
Ruby, sapphire,
Luminescence:
UV Type |
Main color |
Intensity |
Observation Frequency |
|
| | | |
Long Waves (365nm): | Red | Very Strong | Very often | Mid waves (320 nm): | Red | | | Short Waves (254 nm): | Red | Medium | Often | | | | |
Other colors LW: | Violet red , Violet Pink , |
Other colors SW: | Orange , |
Long Waves Picture (365nm)
Rubis, UV LW,
Sivec Marble Quarry, Sivec Mountain, Prilep, Macedonia
Photo & Col. © G. Barmarin
Short Waves Pictures (254nm)
Rubis, UV SW,
Mysore District, Karnataka, India
Photo & Col. © G. Barmarin
Phosphorescence (in the common meaning of the term) seen by naked eye:
No phosphorescence seen by naked eye whatever the type of UV
Comments:
Ruby variety(red): almost always luminescent(Cr3+)
sapphire variety (blue): sometimes weak red or pink luminescence
Other colored sapphires: frequently luminescent with variable intensity.
Main Activator(s) and spectrum:
Most Common Activator: Cr3+
Peaks in the spectrum (nm):
Cr3+ replacing Al : Lines at 692.8, 694.3nm (R1 and R2 lines)
Cr3+ : 658.2 , 668.2 , 674.1 , 680 (small lines)
N-lines (Cr3+ pairs) : 705.8 , 712nm (small lines)
Fe3+ : broad band peaking at 896nm (Sapphire)
No spectrum for the moment
Comments on activators and spectra:
Crookes (1887) and Becquerel (1861) considered pure alumina as fluorescent; but De Boisbaudran (1887) stated that chromium as impurity was the cause of the fluorescence.
Bois and Elias (1908) studied the effect of low temperature and magnetic field on several chromium salt and ruby in particular.
Steady-state luminescent properties of natural corundum Al2O3 were carefully investigated.
Activator: Cr3+ replacing Al giving strong well known 2E->4A2 lines with long decay time
Besides that, much weaker narrow lines present, which are connected with Cr-pairs and more complicated complexes (so called N-lines) (Tarashchan 1978).
Cathodoluminescence: red or light-blue (undetermined origin);
The weaker peaks from the long wavelength side of the principal lines are also known and ascribed to so call N-lines, namely Cr3+ pairs.
Best Locality for luminescence(*):
- Mysore District, Karnataka, India;
- Limecrest Quarry at Sparta, New jersey, USA;
- Limestone quarries around Franklin, Franklin Marble, Franklin, Franklin Mining District, Sussex Co., New Jersey, USA;
- Sterling Mine, Sterling Hill, Ogdensburg, Franklin Mining District, Sussex Co., New Jersey, USA;
- Kleggåsen Ruby Quarry, Froland, Aust-Agder, Norway;
- Fiskenæsset (Fiskenaesset; Qeqertarsuatsiaat), Nuuk (Godthåb), Sermersooq, Greenland;
- Jegdalek (Jagdalek; Jagdalak; Jagdalik) Ruby Mine, Surobi District, Kabol (Kabul) Province, Afghanistan;
- Zazafotsy Quarry, Zazafotsy Commune, Ihosy District, Horombe Region, Fianarantsoa Province, Madagascar;
- Ampanihy District, Southwestern Region, Tuléar Province, Madagascar;
- Ali Abad, Hunza Valley, Gilgit District, Gilgit-Baltistan, Pakistan;
- Hassanabad Nala (Hasanabad), Hunza Valley (near Ali Abad), Gilgit District, Gilgit-Baltistan (Northern Areas), Pakistan;
- Luc Yen, Yenbai Province, Vietnam;
- Ketito, Arusha Region, Tanzania;
- Longido, Mt Kilimanjaro, Kilimanjaro Region, Tanzania (in green chrome-zoisite (anyolite));
- Mundarara Mine, Arusha Region, Tanzania (in green chrome-zoisite (anyolite));
- Khit Ostrov, Northern Karelia, Karelia Republic, Northern Region, Russia;
- Ganesh Himal deposit, Somdang, Rasuwa District, Bagmati Zone, Nepal;
- Mogok Township, Pyin-Oo-Lwin District, Mandalay Division, Burma;
(*)Data are not exhaustive and are limited to the most important localities for fluorescence
Bibliographical Reference for luminescence:
- The Henkel Glossary of Fluorescent Minerals, Dr. Gerhard Henkel, Published by the FMS, 1989 ,
- Fluorescence: Gems and Minerals Under Ultraviolet Light, Manuel Robbins, 1994, Geoscience Press, ISBN 0-945005-13-X ,
- The World of Fluorescent Minerals, Stuart Schneider, Schiffer Publishing, 2006, ISBN 0-7643-2544-2 ,
- Luminescence Spectroscopy of Minerals and Materials, M. Gaft, R. Reisfeld, G. Panczer, Springer Editor, ISBN: 10 3-540-21918-8 ,
- Luminescent Spectra of Minerals, Boris S. Gorobets and Alexandre A. Rogojine, Moscow, 2002 ,
- Ultraviolet Light and Fluorescent Minerals, Th. Warren, S. Gleason, R. Bostwick, et E. Verbeek, 1995, ISBN 0-9635098-0-2 ,
- Handbook of mineralogy, John W. Anthony, Richard A. Bideaux, Kenneth W. Bladh, and Monte C. Nichols, and published by Mineral Da ,
- Handbook of Fluorescent Gems and Minerals, a practical guide for the gem and mineral collector, Jack de Ment, 1949 ,
Luminescence Reference on internet:
Images:
- Franklin, New Jersey, USA: http://www.mindat.org/photo-209427.html
- Sterling Mine, New Jersey, USA: http://www.mindat.org/photo-570635.html
- Kleggåsen Ruby Quarry, Froland, Norway: http://www.mindat.org/photo-564717.html
- Mundarara Mine, Tanzania: http://www.mindat.org/photo-503773.html
- http://www.mindat.org/photo-664838.html
- Jegdalek, Afghanistan: http://www.mindat.org/photo-587426.html
- Jegdalek, Afghanistan: http://www.mindat.org/photo-638917.html
- Jegdalek, Afghanistan: http://www.mindat.org/photo-646439.html
- Khit Ostrov, Russia (LW): http://www.mindat.org/photo-612978.html
- Khit Ostrov, Russia (SW): http://www.mindat.org/photo-612979.html
- Ali Abad, Hunza Valley, Pakistan: http://www.mindat.org/photo-652373.html
- Hunza Valley, Pakistan: http://www.mindat.org/photo-682509.html
- Mysore, India: http://www.mindat.org/photo-674247.html
- Mysore, India: http://www.mindat.org/photo-681096.html
- Ganesh Himal deposit, Nepal http://www.mindat.org/photo-675772.html
- Limecrest Quarry, Sparta, New Jersey, USA: http://www.mindat.org/photo-677648.html
- Mogok, Burma: http://www.mindat.org/photo-694502.html
Mineralogical Reference on internet:
http://www.mindat.org/show.php?name=Corundum
http://webmineral.com/data/Corundum.shtml
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