Weddellite
A valid IMA mineral species - grandfathered
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About Weddellite
The Weddell Sea
Formula:
Ca(C2O4) · (2.5-x)H2O
0 ≤ x ≤ 0.25
Previously reported as CaC2O4·2H2O and CaC2O4·(2+x)H2O
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.
Type Locality:
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).
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 Identifiers
Mindat ID:
4254
Long-form identifier:
mindat:1:1:4254:9
GUID
(UUID V4):
(UUID V4):
1cb867d8-1046-4767-9fce-255b3097c15e
IMA Classification of Weddellite
Approved, 'Grandfathered' (first described prior to 1959)
IMA Formula:
Ca(C2O4) · 2H2O
First published:
1936
Classification of Weddellite
10.AB.40
10 : ORGANIC COMPOUNDS
A : Salts of organic acids
B : Oxalates
10 : ORGANIC COMPOUNDS
A : Salts of organic acids
B : Oxalates
50.1.2.1
50 : ORGANIC COMPOUNDS
1 : Oxalates
50 : ORGANIC COMPOUNDS
1 : Oxalates
31.1.6
31 : Oxalates, Citrates, Mellitates and Acetates
1 : Oxalates
31 : Oxalates, Citrates, Mellitates and Acetates
1 : Oxalates
Mineral Symbols
As of 2021 there are now IMA–CNMNC approved mineral symbols (abbreviations) for each mineral species, useful for tables and diagrams.
| Symbol | Source | Reference |
|---|---|---|
| Wed | IMA–CNMNC | Warr, L.N. (2021). IMA–CNMNC approved mineral symbols. Mineralogical Magazine, 85(3), 291-320. doi:10.1180/mgm.2021.43 |
Pronunciation of Weddellite
Pronunciation:
| Play | Recorded by | Country |
|---|---|---|
| Jolyon Ralph | United Kingdom |
Physical Properties of Weddellite
Vitreous, Silky, Dull
Transparency:
Transparent
Colour:
Colourless, white, yellowish brown to brown; colourless in transmitted light.
Streak:
White
Hardness:
4 on Mohs scale
Cleavage:
None Observed
Mandarino and Witt (1983) report a good {010} cleavage, unlike other descriptions.
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 Weddellite
Type:
Uniaxial (+)
RI values:
nω = 1.523 nε = 1.544
Max Birefringence:
δ = 0.021
Image shows birefringence interference colour range (at 30µm thickness)
and does not take into account mineral colouration.
and does not take into account mineral colouration.
Surface Relief:
Low
Chemistry of Weddellite
Mindat Formula:
Ca(C2O4) · (2.5-x)H2O
0 ≤ x ≤ 0.25
Previously reported as CaC2O4·2H2O and CaC2O4·(2+x)H2O
0 ≤ x ≤ 0.25
Previously reported as CaC2O4·2H2O and CaC2O4·(2+x)H2O
Elements listed:
Common Impurities:
ORG
Crystallography of Weddellite
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 Structure
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Data courtesy of the American Mineralogist Crystal Structure Database. Click on an AMCSD ID to view structure
| ID | Species | Reference | Link | Year | Locality | Pressure (GPa) | Temp (K) |
|---|---|---|---|---|---|---|---|
| 0000777 | Weddellite | Tazzoli V, Domeneghetti M C (1980) The crystal structures of whewellite and weddellite: re-examination and comparison American Mineralogist 65 327-334 |  | 1980 | 0 | 293 | |
| 0020071 | Weddellite | Izatulina 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 2-7 | 2014 | oxalic renal stones of St. Petersburg citizens aged 24-65 years | 0 | 293 | |
| 0020072 | Weddellite | Izatulina 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 2-7 | 2014 | oxalic renal stones of St. Petersburg citizens aged 24-65 years | 0 | 293 | |
| 0020073 | Weddellite | Izatulina 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 2-7 | 2014 | oxalic renal stones of St. Petersburg citizens aged 24-65 years | 0 | 293 | |
| 0020074 | Weddellite | Izatulina 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 2-7 | 2014 | oxalic renal stones of St. Petersburg citizens aged 24-65 years | 0 | 293 | |
| 0020075 | Weddellite | Izatulina 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 2-7 | 2014 | oxalic renal stones of St. Petersburg citizens aged 24-65 years | 0 | 293 | |
| 0020076 | Weddellite | Izatulina 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 2-7 | 2014 | oxalic renal stones of St. Petersburg citizens aged 24-65 years | 0 | 293 | |
| 0020077 | Weddellite | Izatulina 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 2-7 | 2014 | oxalic renal stones of St. Petersburg citizens aged 24-65 years | 0 | 293 | |
| 0020078 | Weddellite | Izatulina 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 2-7 | 2014 | oxalic renal stones of St. Petersburg citizens aged 24-65 years | 0 | 293 | |
| 0020079 | Weddellite | Izatulina 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 2-7 | 2014 | oxalic renal stones of St. Petersburg citizens aged 24-65 years | 0 | 293 | |
| 0020080 | Weddellite | Izatulina 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 2-7 | 2014 | oxalic renal stones of St. Petersburg citizens aged 24-65 years | 0 | 293 | |
| 0020081 | Weddellite | Izatulina 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 2-7 | 2014 | oxalic renal stones of St. Petersburg citizens aged 24-65 years | 0 | 293 | |
| 0020082 | Weddellite | Izatulina 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 2-7 | 2014 | oxalic renal stones of St. Petersburg citizens aged 24-65 years | 0 | 293 | |
| 0020083 | Weddellite | Izatulina 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 2-7 | 2014 | oxalic renal stones of St. Petersburg citizens aged 24-65 years | 0 | 293 | |
| 0020084 | Weddellite | Izatulina 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 2-7 | 2014 | oxalic renal stones of St. Petersburg citizens aged 24-65 years | 0 | 293 | |
| 0020085 | Weddellite | Izatulina 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 2-7 | 2014 | oxalic renal stones of St. Petersburg citizens aged 24-65 years | 0 | 293 | |
| 0020086 | Weddellite | Izatulina 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 2-7 | 2014 | oxalic renal stones of St. Petersburg citizens aged 24-65 years | 0 | 293 | |
| 0020087 | Weddellite | Izatulina 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 2-7 | 2014 | oxalic renal stones of St. Petersburg citizens aged 24-65 years | 0 | 293 |
CIF Raw Data - click here to close
X-Ray Powder Diffraction
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Radiation - Copper Kα
Data courtesy of RRUFF project at University of Arizona, used with permission.
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 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 Environment
Paragenetic Mode(s):
| Paragenetic Mode | Earliest Age (Ga) |
|---|---|
| Near-surface Processes | |
| 24 : Authigenic minerals in terrestrial sediments (see also #17) | |
| Stage 10a: Neoproterozoic oxygenation/terrestrial biosphere | <0.6 |
| 48 : Soil leaching zone minerals | <0.6 |
| 49 : Oxic cellular biomineralization (see also #44) | <0.54 |
| 52 : Guano- and urine-derived minerals | <0.4 |
| 53 : Other minerals with taphonomic origins | <0.4 |
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 Weddellite
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.
Reference:
Bannister, F.A., Hey, M.H. (1936) Report on some crystalline components of the Weddell Sea deposits. Discovery Reports: 13: 60-69.
Synonyms of Weddellite
Other Language Names for Weddellite
Common Associates
Associated Minerals Based on Photo Data:
| 2 photos of Weddellite associated with Ettringite | Ca6Al2(SO4)3(OH)12 · 26H2O |
| 1 photo of Weddellite associated with Fluorite | CaF2 |
Related Minerals - Strunz-mindat Grouping
| 10.AB. | Deveroite-(Ce) | Ce2(C2O4)3 · 10H2O |
| 10.AB.X | Falottaite | MnC2O4 · 3H2O |
| 10.AB. | Uroxite | [(UO2)2(C2O4)(OH)2(H2O)2] · H2O |
| 10.AB. | Andreybulakhite | Ni(C2O4) · 2H2O |
| 10.AB. | Edwindavisite | Cu(C2O4)(NH3) |
| 10.AB.05 | Humboldtine | Fe2+(C2O4) · 2H2O |
| 10.AB.05 | Lindbergite | Mn2+(C2O4) · 2H2O |
| 10.AB.05 | Katsarosite | Zn(C2O4) · 2H2O |
| 10.AB.10 | Glushinskite | Mg(C2O4) · 2H2O |
| 10.AB.15 | Moolooite | Cu(C2O4) · nH2O |
| 10.AB.20 | Stepanovite | NaMgFe3+(C2O4)3 · 8-9H2O |
| 10.AB.25 | Minguzzite | K3Fe3+(C2O4)3 · 3H2O |
| 10.AB.30 | Wheatleyite | Na2Cu(C2O4)2 · 2H2O |
| 10.AB.35 | Zhemchuzhnikovite | NaMgAl(C2O4)3 · 8H2O |
| 10.AB.45 | Whewellite | Ca(C2O4) · H2O |
| 10.AB.47 | Fiemmeite | Cu2(C2O4)(OH)2 · 2H2O |
| 10.AB.50 | Caoxite | Ca(C2O4) · 3H2O |
| 10.AB.50 | Middlebackite | Cu2C2O4(OH)2 |
| 10.AB.52 | Metauroxite | (UO2)2(C2O4)(OH)2(H2O)2 |
| 10.AB.55 | Oxammite | (NH4)2(C2O4) · H2O |
| 10.AB.60 | Natroxalate | Na2(C2O4) |
| 10.AB.60 | Phoxite | (NH4)2Mg2(C2O4)(PO3OH)2(H2O)4 |
| 10.AB.60 | Carboferriphoxite | [(NH4)K(H2CO3)][Fe3+(HPO4)(H2PO4)(C2O4)] |
| 10.AB.60 | Ferriphoxite | [(NH4)2K(H2O)][Fe3+(HPO4)2(C2O4)] |
| 10.AB.65 | Coskrenite-(Ce) | (Ce,Nd,La)2(C2O4)(SO4)2 · 12H2O |
| 10.AB.70 | Levinsonite-(Y) | (Y,Nd,La)Al(C2O4)(SO4)2 · 12H2O |
| 10.AB.75 | Zugshunstite-(Ce) | (Ce,Nd,La)Al(C2O4)(SO4)2 · 12H2O |
| 10.AB.80 | Novgorodovaite | Ca2(C2O4)Cl2 · 2H2O |
Fluorescence of Weddellite
Can fluoresce yellow under long-wave UV.
Other Information
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 Weddellite
mindat.org URL:
https://www.mindat.org/min-4254.html
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References for Weddellite
Localities for Weddellite
symbol to view information about a locality.
The Locality List
- This locality has map coordinates listed.
- This locality has estimated coordinates.
ⓘ - Click for references and 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).
All localities listed without proper references should be considered as questionable.
Antarctica (TL) | |
| Palache et al. (1951) |
Australia | |
| Bridge (1977) |
| Bridge (1973) |
| Bridge et al. (1978) |
Austria | |
| Kolitsch (2015) |
Botswana | |
| Anthony et al. (2016) |
Bulgaria | |
| J. Mincheva-Stefanova & I. Kostov (1994) |
Canada | |
| Gault (1986) |
| Mandarino (1983) |
| Mandarino (1983) | |
Chile | |
| Cheng +9 other references |
China | |
| Qi Zhang et al. (2008) |
Ethiopia | |
| Tribolo et al. (2017) |
Germany | |
| Walenta (2003) |
| Walenta (1992) |
| 54. +1 other reference |
Israel | |
| Cowgill (1989) |
Italy | |
| Tirelli (1976-77) +1 other reference |
| Tirelli (1976-77) +1 other reference |
| Tirelli (1976-77) +2 other references | |
| Del Magro et al. (2000) |
| Kolitsch et al. (2008) | |
| del Magro (2009) |
| Batoni et al. (2004) +1 other reference |
| Del Monte et al. (1983) |
Japan | |
| Masayuki Ohnishi et al. (2011) |
Namibia | |
| Mineralogical Society of America - ... |
| Martini et al. (1999) |
Russia | |
| Artemenko et al. (2023) |
| Grant et al. (2001) |
| Pekov (1998) |
| Pekov (1998) | |
Spain | |
| Iriarte et al. (2013) |
| Benavente +2 other references |
UK | |
| King et al. (1990) |
| Rust S.A. (1983) +2 other references | |
USA | |
| Garvie (2003) |
| Miklancic collection | |
| Kampf et al. (2019) |
| Kampf et al. (2019) | |
| Luetcke (n.d.) |
| G. M. Griffin (1984) |
| G. M. Griffin (1984) | |
| J. A. Mandarino & N. V. Witt (1983) |
| Kearns et al. (2004) |
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