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Sewardite

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Big Photo

Benjamin Hill, Mun. de Benjamin Hill, Sonora, Mexico
© Pavel M. Kartashov

Show Sewardite Photos (5)



Formula:
CaFe
3+
2
(AsO
 
4
)
 
2
(OH)
 
2
System:OrthorhombicColour:Dark red to light orange
Lustre:Vitreous
Name:
For Terry M. Seward, Professor of Geochemistry, ETH, Zürich, Switzerland, who collected the specimen in 1982.


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 (Oshikoto) Region, 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
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.55Carlgieseckeite-(Nd)
NaNdCa
 
3
(PO
 
4
)
 
3
F
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
Spanish:Sewardita

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:
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  • Raman and XRD data at RRUFF project
  • American Mineralogist Crystal Structure Database
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    • 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.
    Hide Locality List
    (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.
    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 (Oshikoto) Region
      • Tsumeb
    		Can Min 40 (2002), 1191
    Mineral and/or Locality
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