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Clarkeite

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Frank Wigglesworth Clarke
Formula:
(Na,Ca,Pb)(UO2)O(OH) · 0-1H2O
Colour:
Dark red-brown, dark brown
Lustre:
Resinous, Waxy, Greasy
Hardness:
4 - 4½
Specific Gravity:
6.39
Crystal System:
Trigonal
Name:
Named in 1931 by Clarence S. Ross, Edward P. Henderson, and Eugene Waldemar Posnjak in honor of Frank Wigglesworth Clarke [March 19, 1847 Boston, Massachusetts, USA - May 23, 1931 Washington, DC, USA], American mineral chemist, and former Chief Chemist of the U.S. Geological Survey. Clarke studied the composition of the Earth's crust and the unit of measure, the clarke, was named as a reference to the local enrichment of a chemical component relative to an average value for the chemistry of the crust.
Clarkeite is a waxy to resinous dark brown replacement of uraninite. It is very uncommon, but is frequently misidentified with brown gummite that is dominated by schoepite-group minerals. Frondel (1956) warned: "Clarkeite is best identified by its X-ray powder pattern. It is indistinguishable from the dark brown types of oxidized uraninite ... and from dense brown types of fourmarierite and vandendriesscheite."


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Classification of ClarkeiteHide

Approved, 'Grandfathered' (first described prior to 1959)
4.GC.05

4 : OXIDES (Hydroxides, V[5,6] vanadates, arsenites, antimonites, bismuthites, sulfites, selenites, tellurites, iodates)
G : Uranyl Hydroxides
C : With additional cations; with mainly UO2(O,OH)6 hexagonal polyhedra
5.4.1.1

5 : OXIDES CONTAINING URANIUM OR THORIUM
4 : AX2O7·xH2O
7.16.32

7 : Oxides and Hydroxides
16 : Oxides of U

Physical Properties of ClarkeiteHide

Resinous, Waxy, Greasy
Transparency:
Translucent
Colour:
Dark red-brown, dark brown
Streak:
Yellow-brown
Hardness:
4 - 4½ on Mohs scale
Fracture:
Conchoidal, Sub-Conchoidal
Density:
6.39 g/cm3 (Measured)    

Optical Data of ClarkeiteHide

Type:
Biaxial (-)
RI values:
nα = 1.997 nβ = 2.098 nγ = 2.108
2V:
Measured: 30° to 50°, Calculated: 32°
Birefringence:
0.111
Max Birefringence:
δ = 0.111
Image shows birefringence interference colour range (at 30µm thickness)
and does not take into account mineral colouration.
Surface Relief:
Very High
Dispersion:
relatively weak

Chemical Properties of ClarkeiteHide

Formula:
(Na,Ca,Pb)(UO2)O(OH) · 0-1H2O
IMA Formula:
Na(UO2)O(OH) · nH2O

Crystallography of ClarkeiteHide

Crystal System:
Trigonal
Cell Parameters:
a = 3.954 Å, c = 17.660 Å
Ratio:
a:c = 1 : 4.466
Unit Cell V:
239.11 ų (Calculated from Unit Cell)
Z:
3
Morphology:
Massive, dense.

X-Ray Powder DiffractionHide

Powder Diffraction Data:
d-spacingIntensity
5.903 (64)
3.365 (56)
3.195 (100)
2.945 (28)
2.707 (34)
1.977 (33)
1.8742 (19)
1.8554 (19)
1.6807 (14)
1.6410 (23)
Comments:
AM 82, p. 615; JCPDS 8-315 has extraneous and differing d-values.

Type Occurrence of ClarkeiteHide

Synonyms of ClarkeiteHide

Other Language Names for ClarkeiteHide

German:Clarkeit
Simplified Chinese:水钠铀矿
Spanish:Clarkeita

Common AssociatesHide

Associated Minerals Based on Photo Data:
Uraninite5 photos of Clarkeite associated with Uraninite on mindat.org.
Gummite4 photos of Clarkeite associated with Gummite on mindat.org.
Autunite3 photos of Clarkeite associated with Autunite on mindat.org.
Cyrtolite3 photos of Clarkeite associated with Cyrtolite on mindat.org.
Fourmarierite2 photos of Clarkeite associated with Fourmarierite on mindat.org.
Kasolite2 photos of Clarkeite associated with Kasolite on mindat.org.
Uranophane1 photo of Clarkeite associated with Uranophane on mindat.org.
Muscovite1 photo of Clarkeite associated with Muscovite on mindat.org.

Related Minerals - Nickel-Strunz GroupingHide

4.GC.10Umohoite(UO2)MoO4 · 2H2OTric.
4.GC.15SpriggitePb3(UO2)6O8(OH)2 · 3H2OMon. 2/m

Related Minerals - Hey's Chemical Index of Minerals GroupingHide

7.16.1UraniniteUO2Iso. m3m (4/m 3 2/m) : Fm3m
7.16.2Schoepite(UO2)8O2(OH)12 · 12H2OOrth. mmm (2/m 2/m 2/m) : Pbca
7.16.3ParaschoepiteUO3 · 2H2OOrth.
7.16.4MetaschoepiteUO3 · 1-2H2OOrth. mmm (2/m 2/m 2/m) : Pbcn
7.16.5MetastudtiteUO4 · 2H2OOrth. mmm (2/m 2/m 2/m) : Pnma
7.16.6Studtite[(UO2)(O2)(H2O)2] · H2OMon.
7.16.7IanthiniteU4+(UO2)5O7 · 10H2OOrth. mm2 : Amm2
7.16.8CompreignaciteK2(UO2)6O4(OH)6 · 7H2OOrth.
7.16.9VandenbrandeiteCu(UO2)(OH)4Tric. 1 : P1
7.16.10RoubaultiteCu2(UO2)3(CO3)2O2(OH)2•4H2OTric. 1 : P1
7.16.11BecquereliteCa(UO2)6O4(OH)6 · 8H2OOrth. mm2 : Pna21
7.16.12RameauiteK2Ca(H[3]2O)(H[5]2O)4[(UO2)6O6(OH)4](H[4]2O)Mon. m : Bb
7.16.13AgrinieriteK2(Ca,Sr)[(UO2)3O3(OH)2]2 · 5H2OOrth.
7.16.14ProtasiteBa(UO2)3O3(OH)2 · 3H2OMon.
7.16.15BillietiteBa(UO2)6O4(OH)6 · 4-8H2OOrth. mm2
7.16.16BauranoiteBa(UO2)2(OH)6 · 1-2H2O
7.16.17Metacalciouranoite(Ca,Ba,Pb,K2)U2O7 · 2H2O
7.16.18Calciouranoite(Ca,Ba,Pb)U2O7 · 5H2O
7.16.19OrthobranneriteU4+U6+Ti4O12(OH)2Orth.
7.16.20Thorutite(Th,U,Ca)Ti2(O,OH)6Mon.
7.16.21Davidite-(La)(La,Ce)(Y,U,Fe)(Ti,Fe)20(O,OH)38Trig.
7.16.22Davidite-(Ce)(Ce,La)(Y,U,Fe)(Ti,Fe)20(O,OH)38Trig. 3 : R3
7.16.23Brannerite(U4+,REE,Th,Ca)(Ti,Fe3+,Nb)2(O,OH)6Mon. 2/m : B2/m
7.16.24FourmarieritePb(UO2)4O3(OH)4 · 4H2OOrth.
7.16.25Richetite(Fe3+,Mg)Pb 8.6(UO2)36O36(OH)24•41H2O Tric.
7.16.26CuritePb3(UO2)8O8(OH)6 · 3H2OOrth. mmm (2/m 2/m 2/m) : Pnma
7.16.27MasuyitePb(UO2)3O3(OH)2 · 3H2OOrth.
7.16.28VandendriesscheitePbU7O22 · 12H2O
7.16.29MetavandendriesscheitePbU7O22 · nH2O n < 12Orth.
7.16.30SayritePb2(UO2)5O6(OH)2 · 4H2OMon.
7.16.31Wölsendorfite(Pb,Ca)U2O7 · 2H2OOrth. mmm (2/m 2/m 2/m) : Cmcm
7.16.33UranosphaeriteBi(UO2)O2(OH)Mon. 2/m

Fluorescence of ClarkeiteHide

Other InformationHide

Health Risks:
radioactive

References for ClarkeiteHide

Reference List:
Sort by Year (asc) | by Year (desc) | by Author (A-Z) | by Author (Z-A)
Ross, Henderson, and Posnjak (1931), American Mineralogist: 16: 213.
Palache, Charles, Harry Berman & Clifford Frondel (1944), The System of Mineralogy of James Dwight Dana and Edward Salisbury Dana Yale University 1837-1892, Volume I: Elements, Sulfides, Sulfosalts, Oxides. John Wiley and Sons, Inc., New York. 7th edition, revised and enlarged: 624-625.
Frondel, Clifford, 1956, Systematic Mineralogy of Uranium and Thorium, USGS Bulletin 1064, pp. 400.
Finch, Robert J. and Ewing, Rodney C., 1997, Clarkeite: New Chemical and Structural Data, American Mineralogist, 82: 607-619.
Finch, R.J. and R.C. Ewing (1997), Clarkeite: New chemical and structural data: American Mineralogist: 82: 607-619.
Kubatko, Karrie-Ann, Katheryn Helean, Alexandra Navrotsky, and Peter C. Burns (2006), Thermodynamics of uranyl minerals: Enthalpies of formation of uranyl oxide hydrates: American Mineralogist: 91: 658-666.

Internet Links for ClarkeiteHide

Localities for ClarkeiteHide

This 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.

Locality ListHide

- This locality has map coordinates listed. - This locality has estimated coordinates. ⓘ - Click for further information on this occurrence. ? - Indicates mineral may be doubtful at this locality. - Good crystals or important locality for species. - World class for species or very significant. (TL) - Type Locality for a valid mineral species. (FRL) - First Recorded Locality for everything else (eg varieties). Struck out - Mineral was erroneously reported from this locality. Faded * - Never found at this locality but inferred to have existed at some point in the past (eg from pseudomorphs.)

All localities listed without proper references should be considered as questionable.
Canada
 
  • Nova Scotia
    • Cumberland Co.
A.K. Chatterjee, "Uranium Mineralization at McLean Point, Cumberland County", Nova Scotia Dept. Mines Report 77-1, 1977.
Czech Republic
 
  • Bohemia (Böhmen; Boehmen)
    • Plzeň Region
      • Planá u Mariánských Lázní (Plan)
Pauliš P., Kopecký S., Černý P. 2007: Uranové minerály České Republiky a jejich naleziště. 1. část. (Kutna Hora, issue 1)
Hungary
 
  • Baranya Co.
    • Mecsek Mts
Koch: Minerals of Hungary, 1985
India
 
  • Rajasthan (Rajputana)
    • Ajmer Division
American Mineralogist: 41: 127-133
Norway
 
  • Aust-Agder
Neumann, H. (1985): Norges Mineraler. Norges geologiske Undersøkelse Skrifter 68, p 90
  • Buskerud
    • Krødsherad
      • Krøderen Lake
Neumann, H. (1985): Norges Mineraler. Norges geologiske Undersøkelse Skrifter 68, pp. 89-90
  • Vest-Agder
    • Lindesnes
      • Vigeland
Sverdrup, T. L. (1959): The pegmatite dyke at Rømteland. Norges Geologiske Undersøkelse 211 (Årbok 1959): 124-196
Romania
 
  • Suceava Co.
    • Suceava district
Hîrtopanu P., Udubaşa G., Scott P., Hârtopanu I. (2004) Uranium sulphide mineralisation in the Bistriţa Mts., East Carpathians, Romania. Romanian Journal of Mineral Deposits 81:108-111
USA
 
  • Alaska
    • Yukon-Koyukuk Borough
      • Sheenjek District
U.S. Geological Survey, 2008, Alaska Resource Data File (ARDF): U.S. Geological Survey Open-File Report 2008-1225.
  • Maine
    • Oxford Co.
      • Newry
Not found according to King, V. T., 1994, Mineralogy of Maine, Descriptive Mineralogy, v. 1
      • Stoneham
Not found according to King & Foord, 1994. Mineralogy of Maine, V. 1.
  • New Hampshire
    • Grafton Co.
      • Grafton
Discredited by Clifford Frondel (1956) Mineral Composition of Gummite, American Mineralogist 41:539-568.; Rocks & Minerals (2005) 80:242-261 New Hampshire Mineral Locality Index
      • Groton
Not found at this locality: Frondel (1956); Foord et al. (1997), Korzeb et al (1997).
    • Rockingham Co.
      • Raymond
Rocks & Minerals (2005) 80:242-261 New Hampshire Mineral Locality Index
  • North Carolina
    • Mitchell Co.
Rocks and Minerals, Sep-Oct,2004
Roger Howell Collection
Rocks and Minerals,Sep-Oct,2004
      • Spruce Pine District
        • Penland
Ross, Henderson, and Posnjak (1931), American Mineralogist: 16: 213.; Arthur Roe and John S. White, Jr. (1976) A Catalog of the Type Specimens in the Mineral Collection, National Museum of Natural History
        • Spruce Pine
Smithsonian Institution Mineral Reference Collection No.R13655-00
          • Greasy Creek Township
Rocks and Minerals,Sep-Oct,2004
www.excaliburmineral.com
Rocks and Minerals,Sep-Oct,2004
    • Yancey Co.
      • Spruce Pine District
        • Celo
          • Micaville
U.S. Geological Survey, 2005, Mineral Resources Data System: U.S. Geological Survey, Reston, Virginia.; American Mineralogist, Volume 82, pages 607–619, 1997
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