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Weddellite

A valid IMA mineral species - grandfathered
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About WeddelliteHide

04084070017271927655564.jpg
The Weddell Sea
Formula:
Ca(C2O4) · (2.5-x)H2O
0 ≤ x ≤ 0.25

Previously reported as CaC2O4·2H2O and CaC2O4·(2+x)H2O
Colour:
Colourless, white, yellowish brown to brown; colourless in transmitted light.
Lustre:
Vitreous, Silky, Dull
Hardness:
4
Specific Gravity:
1.94
Crystal System:
Tetragonal
Name:
Named after its discovery locality, the Weddell Sea, Antarctica. The first natural and non-biologically produced material was described by Bannister and Hey (1936), but they did not name it. Frondel and Prien (1942) used the name weddellite for the first time but gave no data.
Authigenic in bottom sediments and peat; in calcareous lacustrine sediments; also formed by reaction of calcite with oxalic acid derived from lichens; also from solutions derived from bat guano. Known as component of human urinary stones. May also be produced by fungi (e.g., Burford et al., 2003; compare 'Unnamed (Pb Oxalate Dihydrate)'); as such is found in soils and leaf litter; also formed by lichens liivng on basalts, serpentinites, Cu-bearing rocks, gabbroes, dolerites, andesites, volcanic clasts; examples of organisms producing it are numerous, with Acarospora rugulosa, Geastrum spp. and Lecidea lactea, to mention some.

NOTE: Cleaning of any specimens with oxalic acid will lead to crystallisation of whewellite or weddellite if Ca-bearing soluble species are present on the specimen.

Contains zeolitic water. May occur in coral reefs. These observations, as well as confirmation of an additional water site, and the current formula, are taken from Mills & Christy (2016).


Unique IdentifiersHide

Mindat ID:
4254
Long-form identifier:
mindat:1:1:4254:9

Similar NamesHide

WadaliteA valid IMA mineral species(Ca,Mg)6(Al,Fe3+)4((Si,Al)O4)3O4Cl3
WoodalliteA valid IMA mineral speciesMg6Cr2(OH)16Cl2 · 4H2O

IMA Classification of WeddelliteHide

Approved, 'Grandfathered' (first described prior to 1959)
IMA Formula:
Ca(C2)6+O4·2H2O
First published:
1936

Classification of WeddelliteHide

10.AB.40

10 : ORGANIC COMPOUNDS
A : Salts of organic acids
B : Oxalates
50.1.2.1

50 : ORGANIC COMPOUNDS
1 : Oxalates
31.1.6

31 : Oxalates, Citrates, Mellitates and Acetates
1 : Oxalates

Mineral SymbolsHide

As of 2021 there are now IMA–CNMNC approved mineral symbols (abbreviations) for each mineral species, useful for tables and diagrams.

SymbolSourceReference for Standard
WedIMA–CNMNCWarr, L.N. (2021). IMA–CNMNC approved mineral symbols. Mineralogical Magazine, 85(3), 291-320. doi:10.1180/mgm.2021.43

Pronunciation of WeddelliteHide

Pronunciation:
PlayRecorded byCountry
Jolyon RalphUnited Kingdom

Physical Properties of WeddelliteHide

Vitreous, Silky, Dull
Transparency:
Transparent
Colour:
Colourless, white, yellowish brown to brown; colourless in transmitted light.
Streak:
White
Hardness:
Cleavage:
None Observed
Mandarino and Witt (1983) report a good {010} cleavage, unlike other descriptions.
Fracture:
Sub-Conchoidal
Density:
1.94 g/cm3 (Measured)    1.962 g/cm3 (Calculated)

Optical Data of WeddelliteHide

Type:
Uniaxial (+)
RI values:
nω = 1.523 nε = 1.544
Max. Birefringence:
δ = 0.021
Based on recorded range of RI values above.

Interference Colours:
The colours simulate birefringence patterns seen in thin section under crossed polars. They do not take into account mineral colouration or opacity.

Michel-Levy Bar The default colours simulate the birefringence range for a 30 µm thin-section thickness. Adjust the slider to simulate a different thickness.

Grain Simulation You can rotate the grain simulation to show how this range might look as you rotated a sample under crossed polars. Each grain retains its interference colour (retardation) while its brightness falls to black at extinction and reaches a maximum between extinction positions.

Surface Relief:
None to Very Low
Relative to Canada balsam mounting medium (n ≈ 1.537).

This shows the grain boundary and Becke line effect under plane-polarised light, based on the contrast between this mineral's average refractive index and the mounting medium. It does not take into account mineral colouration.
In focus
Interference Figure:
This shows the idealized uniaxial interference figure - the conoscopic (convergent-light, Bertrand-lens-in) view, for a grain cut with the optic axis centred and vertical. The coloured rings are isochromatics, computed with the same physics as the Michel-Lévy bar above; the dark cross is the isogyre.

For a genuinely uniaxial mineral viewed this way, that cross stays perfectly stationary if you rotate the stage - unlike a biaxial mineral, where it splits apart on rotation. That invariance is itself the standard diagnostic test for telling uniaxial and biaxial minerals apart at the microscope.

Chemistry of WeddelliteHide

Mindat Formula:
Ca(C2O4) · (2.5-x)H2O

0 ≤ x ≤ 0.25

Previously reported as CaC2O4·2H2O and CaC2O4·(2+x)H2O
Element Weights:
Element% weight
O54.750 %
Ca27.430 %
C16.440 %
H1.380 %

Calculated from ideal end-member formula.
O
Ca
C
H
Common Impurities:
ORG

Crystallography of WeddelliteHide

Crystal System:
Tetragonal
Class (H-M):
4/m - Dipyramidal
Space Group:
I4/m
Cell Parameters:
a = 12.371 Å, c = 7.357 Å
Ratio:
a:c = 1 : 0.595
Unit Cell V:
1,125.93 ų (Calculated from Unit Cell)
Z:
8
Morphology:
Crystals commonly isolated, with {011}, elongated [010], terminated by {001}; commonly corroded.
Twinning:
Single or multiple twins possibly noted.

Crystal StructureHide

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IDSpeciesReferenceLinkYearLocalityPressure (GPa)Temp (K)
0020087WeddelliteIzatulina A, Gurzhiy V, Frank-Kamenetskaya O (2014) Weddellite from renal stones: Structure refinement and dependence of crystal chemical features on H2O content. American Mineralogist 99 2-72014oxalic renal stones of St. Petersburg citizens aged 24-65 years0293
0020086WeddelliteIzatulina A, Gurzhiy V, Frank-Kamenetskaya O (2014) Weddellite from renal stones: Structure refinement and dependence of crystal chemical features on H2O content. American Mineralogist 99 2-72014oxalic renal stones of St. Petersburg citizens aged 24-65 years0293
0020085WeddelliteIzatulina A, Gurzhiy V, Frank-Kamenetskaya O (2014) Weddellite from renal stones: Structure refinement and dependence of crystal chemical features on H2O content. American Mineralogist 99 2-72014oxalic renal stones of St. Petersburg citizens aged 24-65 years0293
0020084WeddelliteIzatulina A, Gurzhiy V, Frank-Kamenetskaya O (2014) Weddellite from renal stones: Structure refinement and dependence of crystal chemical features on H2O content. American Mineralogist 99 2-72014oxalic renal stones of St. Petersburg citizens aged 24-65 years0293
0020083WeddelliteIzatulina A, Gurzhiy V, Frank-Kamenetskaya O (2014) Weddellite from renal stones: Structure refinement and dependence of crystal chemical features on H2O content. American Mineralogist 99 2-72014oxalic renal stones of St. Petersburg citizens aged 24-65 years0293
0020082WeddelliteIzatulina A, Gurzhiy V, Frank-Kamenetskaya O (2014) Weddellite from renal stones: Structure refinement and dependence of crystal chemical features on H2O content. American Mineralogist 99 2-72014oxalic renal stones of St. Petersburg citizens aged 24-65 years0293
0020081WeddelliteIzatulina A, Gurzhiy V, Frank-Kamenetskaya O (2014) Weddellite from renal stones: Structure refinement and dependence of crystal chemical features on H2O content. American Mineralogist 99 2-72014oxalic renal stones of St. Petersburg citizens aged 24-65 years0293
0020080WeddelliteIzatulina A, Gurzhiy V, Frank-Kamenetskaya O (2014) Weddellite from renal stones: Structure refinement and dependence of crystal chemical features on H2O content. American Mineralogist 99 2-72014oxalic renal stones of St. Petersburg citizens aged 24-65 years0293
0020079WeddelliteIzatulina A, Gurzhiy V, Frank-Kamenetskaya O (2014) Weddellite from renal stones: Structure refinement and dependence of crystal chemical features on H2O content. American Mineralogist 99 2-72014oxalic renal stones of St. Petersburg citizens aged 24-65 years0293
0020078WeddelliteIzatulina A, Gurzhiy V, Frank-Kamenetskaya O (2014) Weddellite from renal stones: Structure refinement and dependence of crystal chemical features on H2O content. American Mineralogist 99 2-72014oxalic renal stones of St. Petersburg citizens aged 24-65 years0293
0020077WeddelliteIzatulina A, Gurzhiy V, Frank-Kamenetskaya O (2014) Weddellite from renal stones: Structure refinement and dependence of crystal chemical features on H2O content. American Mineralogist 99 2-72014oxalic renal stones of St. Petersburg citizens aged 24-65 years0293
0020076WeddelliteIzatulina A, Gurzhiy V, Frank-Kamenetskaya O (2014) Weddellite from renal stones: Structure refinement and dependence of crystal chemical features on H2O content. American Mineralogist 99 2-72014oxalic renal stones of St. Petersburg citizens aged 24-65 years0293
0020075WeddelliteIzatulina A, Gurzhiy V, Frank-Kamenetskaya O (2014) Weddellite from renal stones: Structure refinement and dependence of crystal chemical features on H2O content. American Mineralogist 99 2-72014oxalic renal stones of St. Petersburg citizens aged 24-65 years0293
0020074WeddelliteIzatulina A, Gurzhiy V, Frank-Kamenetskaya O (2014) Weddellite from renal stones: Structure refinement and dependence of crystal chemical features on H2O content. American Mineralogist 99 2-72014oxalic renal stones of St. Petersburg citizens aged 24-65 years0293
0020073WeddelliteIzatulina A, Gurzhiy V, Frank-Kamenetskaya O (2014) Weddellite from renal stones: Structure refinement and dependence of crystal chemical features on H2O content. American Mineralogist 99 2-72014oxalic renal stones of St. Petersburg citizens aged 24-65 years0293
0020072WeddelliteIzatulina A, Gurzhiy V, Frank-Kamenetskaya O (2014) Weddellite from renal stones: Structure refinement and dependence of crystal chemical features on H2O content. American Mineralogist 99 2-72014oxalic renal stones of St. Petersburg citizens aged 24-65 years0293
0020071WeddelliteIzatulina A, Gurzhiy V, Frank-Kamenetskaya O (2014) Weddellite from renal stones: Structure refinement and dependence of crystal chemical features on H2O content. American Mineralogist 99 2-72014oxalic renal stones of St. Petersburg citizens aged 24-65 years0293
0000777WeddelliteTazzoli V, Domeneghetti M C (1980) The crystal structures of whewellite and weddellite: re-examination and comparison American Mineralogist 65 327-334Image19800293
CIF Raw Data - click here to close

X-Ray Powder DiffractionHide

Loading XRD data...
Data Set:
Data courtesy of RRUFF project at University of Arizona, used with permission.
Powder Diffraction Data:
d-spacingIntensity
2.744 Å(100)
6.19 Å(72)
3.35 Å(66)
2.231 Å(63)
1.892 Å(49)
4.43 Å(40)
2.792 Å(38)

Geological EnvironmentHide

Paragenetic Mode(s):
Geological Setting:
Authigenic in bottom sediments and peat; in calcareous lacustrine sediments; also formed by reaction of calcite with oxalic acid derived from lichens; also from solutions derived from bat guano.

Type Occurrence of WeddelliteHide

General Appearance of Type Material:
Tiny isolated crystals
Place of Conservation of Type Material:
The Natural History Museum, London, England: #1936,975 to 1936,977.
Geological Setting of Type Material:
Bottom muds of an Antarctic sea.

Synonyms of WeddelliteHide

Other Language Names for WeddelliteHide

Common AssociatesHide

Associations Based on Photo Data:
2 photos of Weddellite associated with QuartzSiO2
2 photos of Weddellite associated with 'Kidney Stone'
2 photos of Weddellite associated with EttringiteCa6Al2(SO4)3(OH)12 · 26H2O
1 photo of Weddellite associated with WhewelliteCa(C2O4) · H2O
1 photo of Weddellite associated with LöllingiteFeAs2
1 photo of Weddellite associated with FluoriteCaF2

Related Minerals - Strunz-mindat GroupingHide

10.AB.Deveroite-(Ce)Ce2(C2O4)3 · 10H2OMon. 2/m : P21/b
10.AB.EdwindavisiteCu(C2O4)(NH3)Orth. mmm(2/m2/m2/m) : Pbca
10.AB.XFalottaiteMnC2O4 · 3H2OOrth. mmm(2/m2/m2/m)
10.AB.Uroxite [(UO2)2(C2O4)(OH)2(H2O)2] · H2OMon. 2/m : P21/b
10.AB.05KatsarositeZn(C2O4) · 2H2OMon. 2/m : B2/b
10.AB.05AndreybulakhiteNi(C2O4) · 2H2OMon. 2/m : B2/b
10.AB.05HumboldtineFe2+(C2O4) · 2H2OMon. 2/m
10.AB.05LindbergiteMn2+(C2O4) · 2H2OMon. 2/m
10.AB.10GlushinskiteMg(C2O4) · 2H2OMon. 2/m : B2/b
10.AB.15MoolooiteCu(C2O4) · nH2OOrth.
10.AB.20StepanoviteNaMgFe3+(C2O4)3 · 8-9H2OTrig. 3m : P3c1
10.AB.25MinguzziteK3Fe3+(C2O4)3 · 3H2OMon. 2/m : P21/b
10.AB.30WheatleyiteNa2Cu(C2O4)2 · 2H2OTric. 1 : P1
10.AB.35ZhemchuzhnikoviteNaMgAl(C2O4)3 · 8H2OTrig. 3m : P3c1
10.AB.45WhewelliteCa(C2O4) · H2OMon. 2/m : P21/b
10.AB.47FiemmeiteCu2(C2O4)(OH)2 · 2H2OMon. 2/m : P21/b
10.AB.50CaoxiteCa(C2O4) · 3H2OTric. 1 : P1
10.AB.50MiddlebackiteCu2C2O4(OH)2Mon. 2/m : P21/b
10.AB.52Metauroxite(UO2)2(C2O4)(OH)2(H2O)2Tric. 1 : P1
10.AB.55Oxammite(NH4)2(C2O4) · H2OOrth. 222 : P21212
10.AB.60NatroxalateNa2(C2O4)Mon. 2/m : P21/b
10.AB.60Phoxite(NH4)2Mg2(C2O4)(PO3OH)2(H2O)4Mon. 2/m : P21/b
10.AB.60Carboferriphoxite[(NH4)K(H2CO3)][Fe3+(HPO4)(H2PO4)(C2O4)]Tric. 1 : P1
10.AB.60Ferriphoxite[(NH4)2K(H2O)][Fe3+(HPO4)2(C2O4)]Mon. 2/m : P21/b
10.AB.65Coskrenite-(Ce)Ce2(SO4)2(C2O4) · 8H2OTric.
10.AB.70Levinsonite-(Y)(Y,Nd,La)Al(C2O4)(SO4)2 · 12H2OMon. 2/m
10.AB.75Zugshunstite-(Ce)(Ce,Nd,La)Al(C2O4)(SO4)2 · 12H2OMon. 2/m : B2/b
10.AB.80NovgorodovaiteCa2(C2O4)Cl2 · 2H2OMon. 2/m

Fluorescence of WeddelliteHide

Can fluoresce yellow under long-wave UV.

Other InformationHide

Notes:
Dehydrates to Whewellite upon exposure to air. Insoluble in water.
Health Risks:
No information on health risks for this material has been entered into the database. You should always treat mineral specimens with care.

Internet Links for WeddelliteHide

References for WeddelliteHide

Reference List:

Localities for WeddelliteHide

Showing 48 localities.

This map shows a selection of localities that have latitude and longitude coordinates recorded. Click on the Image symbol to view information about a locality. The Image symbol next to localities in the list can be used to jump to that position on the map.
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Locality ListHide

Image - This locality has map coordinates listed. Image - This locality has estimated coordinates. ⓘ - Click for references and further information on this occurrence. ? - Indicates mineral may be doubtful at this locality. Image - Good crystals or important locality for species. Image - 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 (e.g. from pseudomorphs).

All localities listed without proper references should be considered as questionable.
Antarctica (TL)
 
  • West Antarctica
Palache et al. (1951)
Australia
 
  • Western Australia
    • Dundas Shire
      • Madura Roadhouse
Bridge (1977)
    • Laverton Shire
      • Lake Rason
Bridge (1973)
    • Moora Shire
Bridge et al. (1978)
Austria
 
  • Salzburg
    • St. Johann im Pongau District
      • Bad Gastein
Kolitsch (2015)
Botswana
 
  • North-West District
    • Ngamiland West District
Anthony et al. (2016)
Bulgaria
 
  • Sofia City Province
    • Stolichna Municipality
Mincheva-Stefanova et al. (1994)
Canada
 
  • Nunavut
    • Qikiqtaaluk Region
      • Ellesmere Island
Gault (1986)
  • Ontario
    • Haliburton County
      • Minden Hills Township
        • Lutterworth Township
Mandarino (1983)
Mandarino (1983)
Chile
 
  • Tarapacá
    • Iquique Province
      • Iquique
Cheng +9 other references
China
 
  • Inner Mongolia
    • Xilingol League (Xilinguole Prefecture)
      • Xilinhot City (Xilinhaote Co.)
        • Shengli coal field
Qi Zhang et al. (2008)
Ethiopia
 
  • Somali Region
    • Kunama
Tribolo et al. (2017)
Germany
 
  • Baden-Württemberg
    • Freiburg Region
      • Breisgau-Hochschwarzwald
        • Bollschweil
          • St Ulrich
Walenta (2003)
      • Ortenaukreis
        • Oberwolfach
          • Frohnbach valley
Walenta (1992)
      • Waldshut
        • Waldshut-Tiengen
          • Detzeln
Hanneberg et al. (2009) +1 other reference
Israel
 
  • Northern District
    • Safed Subdistrict
      • Galil Elyon Regional Council
Cowgill (1989)
Italy
 
  • Emilia-Romagna
    • Modena Province
      • Prignano sulla Secchia
        • Sassomorello
Tirelli (1976-77) +1 other reference
      • Serramazzoni
Tirelli (1976-77) +1 other reference
Tirelli (1976-77) +2 other references
  • Liguria
    • La Spezia Province
      • Borghetto di Vara
Del Magro et al. (2000)
Kolitsch et al. (2008)
    • Lucca Province
      • Massarosa
        • Massaciuccoli
          • Monte Niquila
del Magro (2009)
      • Stazzema
Batoni et al. (2004) +1 other reference
  • Veneto
    • Metropolitan City of Venice
      • Venice
Del Monte et al. (1983)
Japan
 
  • Kyoto Prefecture
    • Soraku District
      • Wazuka-cho
Masayuki Ohnishi et al. (2011)
Namibia
 
  • Kunene Region
    • Khorixas
Mineralogical Society of America - ...
    • Opuwo Rural
Martini et al. (1999)
Norway
 
  • Trøndelag
    • Ørland
      • Skjelholmen
Johansen (2024)
Russia
 
  • Chelyabinsk Oblast
    • Karabash
Artemenko et al. (2023)
  • Moscow Oblast
    • Ruzsky District
Ivan Novikov analytical data
  • Primorsky Krai
    • Dalnegorsk Urban District
      • Dalnegorsk
Grant et al. (2001)
  • Sakha
    • Polar Yakutia
      • Bulun District
        • Lena River Basin
Pekov (1998)
Pekov (1998)
Spain
 
  • Castile and Leon
    • Segovia
      • Sepúlveda
        • Villaseca
Iriarte et al. (2013)
  • Catalonia
    • Lleida
      • Pallars Jussà
        • Tremp
          • Gurp
Joan Rosell-Riba - Jordi Ibáñez-Insa (2025)
  • Valencian Community
    • Alicante
      • Aspe
Benavente +2 other references
UK
 
  • England
    • Derbyshire
      • North East Derbyshire District
        • Ashover
          • Milltown
King et al. (1990)
Rust S.A. (1983) +2 other references
USA
 
  • Arizona
Garvie (2003)
Miklancic collection
      • Painted Rock Mountains
        • Painted Rock Mining District
          • Theba
Kampf et al. (2019)
Kampf et al. (2019) +1 other reference
    • Pinal County
Luetcke (n.d.)
  • Florida
G. M. Griffin (1984)
G. M. Griffin (1984)
  • Oregon
    • Sherman County
J. A. Mandarino & N. V. Witt (1983)
  • Virginia
    • Amelia County
      • Winterham
Kearns et al. (2004)
 
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