Mindat Logo
Home Page Log In Message Board The Mindat Directory
Register Search Pages Chat Now! (2 online) Mindat Auctions

Powellite

Big Photo

Mahodari, Nasik District, Maharashtra, India
© Paul Bongaerts

Show Powellite Photos (58)
Formula:
Ca[MoO
 
4
]
System:TetragonalColour:Yellow, straw-yellow, ...
Lustre:Sub-Adamantine, Resinous, PearlyHardness:3½ - 4
Name:Named after the American geologist and explorer, John Wesley Powell (1834-1902), former Director of the U.S. Geological Survey.
Isostructural with:Scheelite


Scheelite Group. Powellite-Scheelite Series.

An uncommon secondary mineral, typically formed in the oxidation zones of molybdenum-bearing hydrothermal deposits, rarely in basalt cavities, tactites, and granite pegmatites.

Classification of Powellite

IMA status:Valid - first described prior to 1959 (pre-IMA) - "Grandfathered"
Strunz 8th edition ID:6/G.01-10
Nickel-Strunz 10th (pending) edition ID:7.GA.05

7 : SULFATES (selenates, tellurates, chromates, molybdates, wolframates)
G : Molybdates, Wolframates and Niobates
A : Without additional anions or H2O
Dana 7th edition ID:48.1.2.2
Dana 8th edition ID:48.1.2.2

48 : ANHYDROUS MOLYBDATES AND TUNGSTATES
1 : AXO4
Hey's CIM Ref.:27.3.2

27 : Sulphites, Chromates, Molybdates and Tungstates
3 : Molybdates
mindat.org URL:http://www.mindat.org/min-3275.html
Please feel free to link to this page.

Type Occurrence of Powellite

Type Locality:Peacock Mine (South Peacock; Darland; Peacock & South Peacock), Cuprum, Seven Devils District, Adams Co., Idaho, USA
Place of Conservation of Type Material:U.S. National Museum of Natural History, Washington, D.C., USA: #80674.
Year of Discovery:1891

Occurrences of Powellite

Geological Setting:Oxidation zone of hydrothermal deposits

Physical Properties of Powellite

Lustre:Sub-Adamantine, Resinous, Pearly
Diaphaneity (Transparency):Transparent, Translucent
Comment:Lustre sub-adamantine on crystal faces; greasy on fracture surfaces. Pearly lustre manifests on foliated pseudmorphous material.
Colour:Yellow, straw-yellow, yellow-brown, brown, greenish yellow, grey, blue or black, colourless; black material is deep blue in transmitted light.
Comment:May exhibit zoned colouration.
Hardness (Mohs):3½ - 4
Cleavage:Poor/Indistinct
Indistinct on {112} {011} and {001}.
Fracture:Irregular/Uneven
Density (measured):4.26 g/cm3
Density (calculated):4.255 g/cm3

Crystallography of Powellite

Crystal System:Tetragonal
Class (H-M):4/m - Dipyramidal
Space Group:I41/a
Cell Parameters:a = 5.222(1) Å, c = 11.425(3) Å
Ratio:a:c = 1 : 2.188
Unit Cell Volume:V 312.92 ų
Z:4
Morphology:Crystals dipyramidal {111}, with {011} and {112}; less commonly flat tabular to paper-thin on {001}, exhibiting many minor forms. Form e sometimes striated parallel to the intersection with vertical plane {110}; diagonal striations parallel to {131} observed on e and W. Tetragonal-dipyramidal symmetry evident only in the zones of [111]. Forms crusts; pulverulent; ocherous; massive.
Comment:On synthetic material
X-Ray Powder Diffraction:
Image Loading

Radiation - Copper Kα
Data Set:
Horizontal Axis: ° to ° Vertical Axis: % Source Data: Filtered Data: Peaks:
Data courtesy of RRUFF project at University of Arizona, used with permission.

Optical Data of Powellite

Type:Uniaxial (+)
RI values: nω = 1.974 nε = 1.984
Maximum Birefringence:δ = 0.010

Chart shows birefringence interference colour range (at 30µm thickness) and does not take into account mineral colouration.
Surface Relief:Very High
Pleochroism:Visible
Comments:In deeply colored specimens (Houghton County, Michigan, USA):
O = Blue
E = Green

Chemical Properties of Powellite

Formula:
Ca[MoO
 
4
]
Essential elements:Ca, Mo, O
All elements listed in formula:Ca, Mo, O
Analyical Data:
CaO (28.04%)
MoO3 (71.96%)
Empirical Formula:
CaMoO
 
4
Common Impurities:W

Relationship of Powellite to other Species

Series:Forms a series with Scheelite (see here)
Related to:
  • Scheelite Group
    • Common Associates:
    StilbiteMolybdeniteMolybdeniteLaumontiteApophyllite
    Related Minerals - Nickel-Strunz Grouping):
    7.GA.05Fergusonite-(Ce)
    (Ce,La,Nd)NbO
     
    4
    7.GA.05Fergusonite-(Nd)
    (Nd,Ce)(Nb,Ti)O
     
    4
    7.GA.05Fergusonite-(Y)
    YNbO
     
    4
    7.GA.05Formanite-(Y)
    YTaO
     
    4
    7.GA.05Scheelite
    Ca[WO
     
    4
    		]
    7.GA.05Stolzite
    Pb[WO
     
    4
    		]
    7.GA.05Wulfenite
    Pb[MoO
     
    4
    		]
    7.GA.10Paraniite-(Y)
    Ca
     
    2
    		Y(AsO
     
    4
    		)(WO
     
    4
    		)
     
    2
    Related Minerals - Hey's Index Grouping:
    27.3.1Lindgrenite
    Cu
     
    3
    		[OH|MoO
     
    4
    		]
     
    2
    27.3.3Wulfenite
    Pb[MoO
     
    4
    		]
    27.3.4Koechlinite
    (BiO)
     
    2
    		[MoO
     
    4
    		]
    27.3.5Sedovite
    U(MoO
     
    4
    		)
     
    2
    27.3.6Mourite
    UMo
     
    5
    		O
     
    12
    		(OH)
     
    10
    27.3.7Iriginite
    UO
     
    2
    		Mo
     
    2
    		O
     
    7
    		·3H
     
    2
    		O
    27.3.8Umohoite
    (UO
     
    2
    		)MoO
     
    4
    		·4H
     
    2
    		O
    27.3.9Moluranite
    U(UO
     
    2
    		)
     
    2
    		Mo
     
    5
    		O
     
    19
    		·12H
     
    2
    		O ?
    27.3.10Cousinite
    MgU
     
    2
    		Mo
     
    2
    		O
     
    11
    		·6H
     
    2
    		O
    27.3.11Calcurmolite
    (Ca,Na)
     
    2
    		(UO
     
    2
    		)
     
    3
    		Mo
     
    2
    		(O,OH)
     
    11
    		·nH
     
    2
    		O
    27.3.12Tengchongite
    CaO·6UO
     
    3
    		·2MoO
     
    3
    		·12H
     
    2
    		O
    27.3.13Kamiokite
    Fe
     
    2
    		Mo
     
    3
    		O
     
    8
    27.3.14Ferrimolybdite
    Fe
     
    2
    		[MoO
     
    4
    		]
     
    3
    		 · nH
     
    2
    		O

    Other Names for Powellite

    German names:
    Powellit
    Russian names:
    Повеллит
    Spanish names:
    Powellita

    Other Information

    Fluorescence in UV light:Creamy white or yellow to golden yellow (SW UV).
    Other Information:May replace molybdenite leaving a material with a foliated structure appearance. Alters to Ferrimolybdite.

    Decomposed by HCl and HNO3.
    Health Warning:No information on health risks for this material has been entered into the database. You should always treat mineral specimens with care.

    References for Powellite

    Reference List:Melville (1891) American Journal of Science: 41: 138.

    Koenig and Hubbard (1893) American Journal of Science: 46: 356.

    Michel (1894) Bulletin de la Société française de Minéralogie: 17: 612.

    Palache, C. (1899) American Journal of Science: 7: 367.

    Pilipenko (1915) Bulletin of the Imperial Tomsk University, no. 63 [Min. Abs. (1923): 2: 109].

    Larsen, E.S. (1921) The Microscopic Determination of the Nonopaque Minerals, First edition, USGS Bulletin 679: 122.

    Zambonini (1923) Zeitschrift für Kristallographie, Mineralogie und Petrographie, Leipzig: 58: 248.

    Vegard (1926) Philosophical Magazine and Journal of Science: 1: 1151.

    Hintze, Carl (1889) Handbuch der Mineralogie. Berlin and Leipzig. 6 volumes: 1 [3B]: 4036.

    Pough (1937) American Mineralogist: 22: 57.

    Maucher (1938) Zs. Angew. Min.: 1 : 103.

    Gianella (1941) University of Nevada Bull. 35, no. 6: 80.

    Palache, C., Berman, H., & Frondel, C. (1951), The System of Mineralogy of James Dwight Dana and Edward Salisbury Dana, Yale University 1837-1892, Volume II. John Wiley and Sons, Inc., New York, 7th edition, revised and enlarged, 1124 pp.: 1079-1081.

    National Bureau of Standards Circular 539 (1956), 6, 22.

    Bulletin of the Mineralogical and Geological Society, Prague (1982): 27: 197-200.

    Hazen, R.M., L.W. Finger, and J.W.E. Mariathasan (1985) High-pressure crystal chemistry of scheelite-type tungstates and molybdates. Journal of Physical Chemistry Solids, 46, 253–263.

    Anthony, J.W., Bideaux, R.A., Bladh, K.W., and Nichols, M.C. (2003) Handbook of Mineralogy, Volume V. Borates, Carbonates, Sulfates. Mineral Data Publishing, Tucson, AZ, 813pp.: 563.

    Internet Links for Powellite

    Search Engines:
  • Look for Powellite on Google
  • Look for Powellite images on Google
    • External Links:
  • Look for Powellite on Webmineral
  • Look for Powellite on Athena Mineralogy
  • Look for Powellite on Wikipedia
  • Look for Powellite on Mineralien Atlas
  • Raman and XRD data at RRUFF project
  • American Mineralogist Crystal Structure Database
  • Search for Powellite in the Natural History Museum (London) online catalogue
  • Powellite details from Handbook of Mineralogy (PDF)
    • Mineral Dealers:
  • Buy fine minerals and gemstones from Pala International
  • Mineral Classics - Worldwide Collector Quality Minerals and Gems
  • Lapis Mineral Magazin
  • Fine Minerals from Dan Weinrich Minerals
  • Wilensky Fine Minerals
  • Buy Fine Minerals from mineralsweb.com
  • rare and unusual minerals mainly crystallized
  • High-end worldwide specimens & outstanding customer service
  • Fabre Minerals - search for Powellite specimens
  • Buy from David K Joyce minerals
  • Top quality minerals from Kristalle of California
  • Rare and Unusual minerals at Mineralogical Research Company
    • Jobs:
  • Mining & Geology Jobs

    • Page Sponsor

    Sponsorship:This page is currently not sponsored. Click here to find out how you can sponsor this page.

    Localities for Powellite

    Show Locality List (341 Items)
    The map shows a selection of localities that have latitude and longitude coordinates recorded. Click on the symbol to view information about a locality. The symbol next to localities in the list can be used to jump to that position on the map.
    These maps work faster with Firefox!
    Mineral and/or Locality
    Google
     
    www.mindat.org Web
    Copyright © Jolyon & Ida Ralph 1993-2008. Site Map. Locality, mineral & photograph data are the copyright of the individuals who submitted them.Further information contact the Site hosted & developed by Jolyon Ralph. Mindat.org is an online information resource dedicated to providing free mineralogical information to all. Mindat relies on the contributions of hundreds of members and supporters. If you would like to add information to improve the quality of our database, then click here to register.