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Sewardite

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Formula:
CaFe
3+
2
(AsO
 
4
)
 
2
(OH)
 
2
System:OrthorhombicColour:Dark red to light orange
Lustre:Vitreous
Name:
Named in honour of Terry Maxwell Seward (b. 1940), Canadian geochemist, Professor of Geochemistry, Intstitut für Mineralogie und Petrographie, ETH, (Swiss Federal Institute of Technology), Zürich, Switzerland. Seward’s research focuses on the chemistry of fluids on and in the earth’s crust, including low temperature aqueous systems, metal speciation, dispersion of heavy metals connected with toxic waste disposal and sea-floor hydrothermal systems.


The calcium analogue of Carminite.

Classification of Sewardite

IMA status:Approved
Nickel-Strunz 10th (pending) edition ID:8.BH.30

8 : PHOSPHATES, ARSENATES, VANADATES
B : Phosphates, etc., with additional anions, without H2O
H : With medium-sized and large cations, (OH,etc.):RO4 = 1:1
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Type Occurrence of Sewardite

Type Locality:Tsumeb Mine (Tsumcorp Mine), Tsumeb, Otjikoto Region (Oshikoto), Namibia

Physical Properties of Sewardite

Lustre:Vitreous
Diaphaneity (Transparency):Transparent, Translucent
Colour:Dark red to light orange
Streak:Reddish-brown

Crystallography of Sewardite

Crystal System:Orthorhombic
Class (H-M):mmm (2/m 2/m 2/m) - Dipyramidal
Space Group:Cccm {C2/c 2/c 2/m}
Cell Parameters:a = 16.461Å, b = 7.434Å, c = 12.131Å
Ratio:a:b:c = 2.214 : 1 : 1.632
Unit Cell Volume:V 1,484.48 ų (Calculated from Unit Cell)

Chemical Properties of Sewardite

Formula:
CaFe
3+
2
(AsO
 
4
)
 
2
(OH)
 
2
Simplified for copy/paste:CaFe3+2(AsO4)2(OH)2
Essential elements:As, Ca, Fe, H, O
All elements listed in formula:As, Ca, Fe, H, O

Relationship of Sewardite to other Species

Related Minerals - Nickel-Strunz Grouping):

- +
8.BH.05Thadeuite
Ca(Mg,Fe
2+
 
)
 
3
(PO
 
4
)
 
2
(OH,F)
 
2
8.BH.10Durangite
NaAl(AsO
 
4
)F
8.BH.10Isokite
CaMg(PO
 
4
)F
8.BH.10Lacroixite
NaAl(PO
 
4
)F
8.BH.10Maxwellite
NaFe
3+
 
(AsO
 
4
)F
8.BH.10Panasqueiraite
CaMg(PO
 
4
)(OH,F)
8.BH.10Tilasite
CaMg(AsO
 
4
)F
8.BH.15Drugmanite
Pb(Fe
3+
 
,Al)
 
2
(PO
 
4
)
 
2
(OH)
 
2
8.BH.20Bjarebyite
(Ba,Sr)(Mn
2+
 
,Fe
2+
 
,Mg)
 
2
Al
 
2
(PO
 
4
)
 
3
(OH)
 
3
8.BH.20Cirrolite
Ca
 
3
Al
 
2
(PO
 
4
)
 
3
(OH)
 
3
(?)
8.BH.20Kulanite
Ba(Fe
2+
 
,Mn
2+
 
,Mg)
 
2
(Al,Fe
3+
 
)
 
2
(PO
 
4
)
 
3
(OH)
 
3
8.BH.20Penikisite
Ba(Mg,Fe
2+
 
,Ca)
 
2
Al
 
2
(PO
 
4
)
 
3
(OH)
 
3
8.BH.20Perloffite
Ba(Mn
2+
 
,Fe
2+
 
)
 
2
Fe
3+
2
(PO
 
4
)
 
3
(OH)
 
3
8.BH.20Johntomaite
BaFe
2+
2
Fe
3+
2
(PO
 
4
)
 
3
(OH)
 
3
8.BH.25Bertossaite
(Li,Na)
 
2
(Ca,Fe
2+
 
,Mn
2+
 
)Al
 
4
(PO
 
4
)
 
4
(OH,F)
 
4
8.BH.25Palermoite
(Li,Na)
 
2
(Sr,Ca)Al
 
4
(PO
 
4
)
 
4
(OH)
 
4
8.BH.30Carminite
PbFe
3+
2
(AsO
 
4
)
 
2
(OH)
 
2
8.BH.35Adelite
CaMg(AsO
 
4
)(OH)
8.BH.35Arsendescloizite
PbZn(AsO
 
4
)(OH)
8.BH.35Austinite
CaZn(AsO
 
4
)(OH)
8.BH.35Cobaltaustinite
CaCo(AsO
 
4
)(OH)
8.BH.35Conichalcite
CaCu(AsO
 
4
)(OH)
8.BH.35Duftite
PbCu(AsO
 
4
)(OH)
8.BH.35Gabrielsonite
PbFe(AsO
 
4
)(OH)
8.BH.35Nickelaustinite
Ca(Ni,Zn)(AsO
 
4
)(OH)
8.BH.35Tangeite
CaCu(VO
 
4
)(OH)
8.BH.35Gottlobite
CaMg(VO
 
4
,AsO
 
4
)(OH)
8.BH.35Hermannroseite
CaCu(PO
 
4
)(OH)
8.BH.40Čechite
Pb(Fe
2+
 
,Mn
2+
 
)(VO
 
4
)(OH)
8.BH.40Descloizite
Pb(Zn,Cu)(VO
 
4
)(OH)
8.BH.40Mottramite
PbCu(VO
 
4
)(OH)
8.BH.40Pyrobelonite
PbMn
2+
 
(VO
 
4
)(OH)
8.BH.45Bayldonite
PbCu
 
3
(AsO
 
4
)
 
2
(OH)
 
2
8.BH.45Vésigniéite
BaCu
 
3
(VO
 
4
)
 
2
(OH)
 
2
8.BH.50Paganoite
NiBi(AsO
 
4
)O
8.BH.55Jagowerite
BaAl
 
2
(PO
 
4
)
 
2
(OH)
 
2
8.BH.60Attakolite
(Ca,Sr)Mn(Al,Fe)
 
4
(HPO
 
4
,PO
 
4
)
 
3
(SiO
 
4
,PO
 
4
)(OH)
 
4
8.BH.65Leningradite
PbCu
 
3
(VO
 
4
)
 
2
Cl

Other Names for Sewardite

Synonyms:
IMA2001-054
Other Languages:
German:Sewardit
Russian:Соуардит
Simplified Chinese:砷钙铁矿
Spanish:Sewardita
Traditional Chinese:砷鈣鐵礦

Other Information

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 Sewardite

Reference List:

- +
Roberts, A.C., Cooper, M.A., Hawthorne, F.C., Criddle, A.J., Stirling, J.A.R. (2002) Sewardite, CaFe3+2(AsO4)2(OH)2, the Ca-analogue of carminite, from Tsumeb, Namibia: description and crystal structure. Canadian Mineralogist: 40: 1191-1198.

Kolitsch, U. (2002) Sewardite from the Mina Ojuela, Mexico: a second occurrence. Lapis 27(12), 43 (in German).

Internet Links for Sewardite

Search Engines:
  • Look for Sewardite on Google
  • Look for Sewardite images on Google
  • External Links:
  • Look for Sewardite on Webmineral
  • Look for Sewardite on Athena Mineralogy
  • Look for Sewardite on Wikipedia
  • Look for Sewardite on Mineralien Atlas
  • Raman and XRD data at RRUFF project
  • American Mineralogist Crystal Structure Database
  • Mineral Dealers:
  • Rare and Unusual minerals at Mineralogical Research Company
  • Fine Minerals from Weinrich Minerals, Inc.
  • Mineral Classics - Worldwide Collector Quality Minerals and Gems
  • Buy fine minerals and gemstones from Pala International
  • DAKOTA MATRIX offers Cabinet and Rare Species from Worldwide Localities.
  • Fine and rare minerals from mintreasure.com
  • Search for Sewardite on Well-Arranged Molecules
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  • Lapis Mineral Magazin
  • Buy RARE Minerals from Rocks of Africa
  • Find Sewardite on www.crystalclassics.co.uk
  • Fabre Minerals - search for Sewardite specimens
  • Localities for Sewardite

    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.
    (TL) indicates type locality. ? indicates mineral may be doubtful at this locality. All other localities listed without reference should be considered as uncertain and unproven until references can be found.
    France
     
    • Limousin
      • Haute-Vienne
        • Nantiat
          • Vaulry
    Patrice Queneau Collection
    Mexico
     
    • Durango
      • Mun. de Mapimí
        • Mapimí
    Kolitsch, U. (2002): Sewardite from the Mina Ojuela, Mexico: a second occurrence. Lapis 27 (12), 43. (in German). Mineralogical Record (2003) 34:5 The Ojuela Mine
    • Sonora
      • Mun. de Benjamin Hill
    Mikhail Murashko data
      • Mun. de Trincheras
        • La Mur
    www.mindat.org/mesg-7-59761.html
    Namibia
     
    • Otjikoto Region (Oshikoto)
      • Tsumeb
    Can Min 40 (2002), 1191
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