Database of luminescent minerals 

POWELLITE

Chemical formula: CaMoO₄

Family: Tungstates, Molybdates

Status: IMA-GP

Crystal system : Tetragonal

Display mineral: OUI

Luminescence:

Daylight picture

POWELLITE, India.

Col. G.Barmarin; Photo: G. Barmarin

Shortwave (254nm) picture

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

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Phosphorescence (in the common sense of the term) observable with the naked eye:

No data

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).

Activator(s) and spectrum:

Activator(s): MoO₄^2-, (UO₂)²⁺ (ion Uranyle) en impureté,  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

Col. G.Barmarin; Photo: G. Barmarin

Spectrum Galery:

  
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Comments on spectrum and activators:

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 localities for fluorescence (*):

• 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;

(*)The data are not exhaustive and are limited to a few remarkable localities for fluorescence

Bibliographic 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 ,

Reference for luminescence on the Internet:

Mineralogical reference on the Internet:

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

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

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