Database of luminescent Minerals

POWELLITE

Chemical Formula: CaMoO₄

Familly: Tungstates, Molybdates

Status: IMA-GP

Crystal System: Tetragonal

Mineral for Display: Yes

Luminescence:

Daylight Picture

POWELLITE, India.

Col. G.Barmarin; Photo: G. Barmarin

Short Waves Pictures (254nm)

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

Galerie de photos:

     To the gallery (10 images in the gallery)

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

Comments:

The tungstates of calcium, strontium, magnesium and zinc, and the molybdates of calcium are known to show luminescence upon excitation by cathode rays or short-wave ultra-violet radiation. It is commonly assumed that this luminescence is characteristic of the tungstate and molybdate groups. The reason why other tungstates and molybdates are found to be non-luminescent is probably the temperature-quenching (see Nature article by F.  A. Kröger in 1947 in the bibliography).

Main Activator(s) and spectrum:

Most Common Activator: MoO₄^2-

Other activators:            (UO₂)²⁺ (Uranyl ion) as impurities , Er³⁺ , Pr³⁺ , Nd³⁺ ,

Peaks in the spectrum (nm):

MoO₄^2- : Broad band peaking at 530 - 550 nm (Gorobets)

(Lifetime: 30 μs)

UO₂²⁺ : 650nm (uranyl complexes substituting to molybdenum (Panczer et al.))

Nd³⁺ : 810, 870nm

  To the spectrum gallery (1 spectra in the gallery)

Comments on activators and spectra:

The natural photoluminescence emission of ordered CaMoO₄ is attributed to an intrinsic slight distortion of the [MoO₄] tetrahedral goup.

The decay time is 200 μs .

Under 532 nm cw excitation the luminescence of Pr³⁺, Er³⁺, Nd³⁺ as well as [UO₂]²⁺ were revealed in powellite found associated with pitchblende and molybdenite in South Kazakhstan (Bota-Burum Mo-U deposits). (Gaft)

Best Locality for luminescence(*):

• Pandulena quarry, Nasik district, India;
• Mahodari, Nasik, Pune (Poona), Maharashtra, India;
• Nangaon, Aurangabad District, Maharashtra, India;
• Jalgaon, Maharashtra, India;
• Ahmednagar District, Maharashtra, India;
• Shakur Quarry, Nashik District, Maharashtra, India (with celadonite inclusions, fluo green);
• Ultevis, Jokkmokk, Norrbotten County, Sweden;
• Jardinera No. 1 Mine, Inca de Oro mining district, Chañaral Province, Atacama, Chile;

(*)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 ,
• Luminescent Spectra of Minerals, Boris S. Gorobets and Alexandre A. Rogojine, Moscow, 2002 ,

Luminescence Reference on internet:

• The Langesundsfjord: history, geology, pegmatites, minerals, Alf Olav Larsen, Bode Verlag Gmbh, 2010 ISBN 978-3-925094-97-2
• F. A. KRÖGER , Fluorescence of Tungstates and Molybdates,Nature,159, pages674–675(1947)
• MONT-SAINT-HILAIRE, History, Geology, Mineralogy, Laszlo HORVATH, The Canadian Mineralogist, Special Publication 14, 2019

 

Images:

 

• Ultevis, Sweden: https://www.mindat.org/photo-167365.html
• Jardinera No. 1 Mine, Atacama, Chile: https://www.mindat.org/photo-143047.html
• Nashik, India (with celadonite inclusions, fluo green): https://www.mindat.org/photo-201265.html
• Nashik, India: https://www.mindat.org/photo-625344.html
• Franklin, NJ, USA: https://www.mindat.org/photo-901746.html

Mineralogical Reference on internet:

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

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

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