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Eugsterite

Formula:
Na
 
4
Ca(SO
 
4
)
 
3
·2H
 
2
O
System:MonoclinicColour:Colorless
Hardness:1 - 2
Name:For Hans Eugster, Johns Hopkins University, Baltimore, Maryland
This page provides mineralogical data about Eugsterite.

Classification of Eugsterite

IMA status:Approved
Strunz 8th edition ID:6/C.21-30
Nickel-Strunz 10th (pending) edition ID:7.CD.25

7 : SULFATES (selenates, tellurates, chromates, molybdates, wolframates)
C : Sulfates (selenates, etc.) without additional anions, with H2O
D : With only large cations
Dana 8th edition ID:29.4.2.1

29 : HYDRATED ACID AND NORMAL SULFATES
4 : AmBn(XO4)p·xH2O, with (m+n):p < 3:2 and > 1:1
Hey's CIM Ref.:25.4.6

25 : Sulphates
4 : Sulphates of Ca, Sr and Ba
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Type Occurrence of Eugsterite

Co-type Localities:Luanda, Lake Victoria, Kenya
Sindo, Lake Victoria, Kenya
Karapinar, Great Konya Basin, Konya Province, Central Anatolia Region, Turkey
Place of Conservation of Type Material:National Museum, Leiden, Netherlands
Year of Discovery:1981
Geological Setting of type material:Efforvescences in salt pans
Associated Minerals at type locality:
ThenarditeHalite

Physical Properties of Eugsterite

Diaphaneity (Transparency):Transparent
Colour:Colorless
Hardness (Mohs):1 - 2

Crystallography of Eugsterite

Crystal System:Monoclinic
Morphology:Thin fibers

Optical Data of Eugsterite

Type:Biaxial
RI values: nα = 1.492 nγ = 1.496
Maximum Birefringence:δ = 0.004

Chart shows birefringence interference colour range (at 30µm thickness) and does not take into account mineral colouration.
Surface Relief:Moderate
Dispersion:r > v strong

Chemical Properties of Eugsterite

Formula:
Na
 
4
Ca(SO
 
4
)
 
3
·2H
 
2
O
Essential elements:Ca, H, Na, O, S
All elements listed in formula:Ca, H, Na, O, S

Relationship of Eugsterite to other Species

Related Minerals - Nickel-Strunz Grouping):

- +
7.CD.05Matteuccite
NaHSO
 
4
·H
 
2
O
7.CD.10Mirabilite
Na
 
2
SO
 
4
·10H
 
2
O
7.CD.15Lecontite
(NH
 
4
,K)Na(SO
 
4
)·2H
 
2
O
7.CD.20Hydroglauberite
Na
 
10
Ca
 
3
(SO
 
4
)
 
8
·6H
 
2
O
7.CD.30Görgeyite
K
 
2
Ca
 
5
(SO
 
4
)
 
6
·H
 
2
O
7.CD.35Koktaite
(NH
 
4
)
 
2
Ca(SO
 
4
)
 
2
·H
 
2
O
7.CD.35Syngenite
K
 
2
Ca(SO
 
4
)
 
2
·H
 
2
O
7.CD.40Gypsum
Ca[SO
 
4
] · 2H
 
2
O
7.CD.45Bassanite
Ca[SO
 
4
] · 0.5H
 
2
O
7.CD.50Zircosulfate
(Zr,Ti)(SO
 
4
)
 
2
·4H
 
2
O
7.CD.55Schieffelinite
Pb
 
8
(TeO
 
4
)
 
5
(SO
 
4
)
 
3
·8H
 
2
O
7.CD.60Montanite
Bi
 
2
[TeO
 
6
] · 2H
 
2
O
7.CD.65Omongwaite
Na
 
2
Ca
 
5
(SO
 
4
)
 
6
·3H
 
2
O
Related Minerals - Hey's Index Grouping:

- +
25.4.1Anhydrite
CaSO
 
4
25.4.2Bassanite
Ca[SO
 
4
] · 0.5H
 
2
O
25.4.3Gypsum
Ca[SO
 
4
] · 2H
 
2
O
25.4.4Glauberite
Na
 
2
Ca(SO
 
4
)
 
2
25.4.5Cesanite
Na
 
3
Ca
 
2
[OH|(SO
 
4
)
 
3
]
25.4.7Hydroglauberite
Na
 
10
Ca
 
3
(SO
 
4
)
 
8
·6H
 
2
O
25.4.8Syngenite
K
 
2
Ca(SO
 
4
)
 
2
·H
 
2
O
25.4.9Görgeyite
K
 
2
Ca
 
5
(SO
 
4
)
 
6
·H
 
2
O
25.4.10Polyhalite
K
 
2
Ca
 
2
Mg(SO
 
4
)
 
4
·2H
 
2
O
25.4.11Koktaite
(NH
 
4
)
 
2
Ca(SO
 
4
)
 
2
·H
 
2
O
25.4.12Ye'elimite
Ca
 
4
Al
 
6
[O
 
12
|SO
 
4
]
25.4.13Ettringite
Ca
 
6
Al
 
2
[(OH)
 
4
|SO
 
4
]
 
3
 · 26H
 
2
O
25.4.14Bentorite
Ca
 
6
(Cr
3+
 
,Al)
 
2
[(OH)
 
4
|SO
 
4
]
 
3
 · 26H
 
2
O
25.4.15Celestine
SrSO
 
4
25.4.16Kalistrontite
K
 
2
Sr(SO
 
4
)
 
2
25.4.17Baryte
BaSO
 
4

Other Names for Eugsterite

Synonyms:
IMA1980-008
Other Languages:
German:Eugsterit
Spanish:Eugsterita

Other Information

Other Information:Soluble in water
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 Eugsterite

Reference List:American Mineralogist: 66: 632-636.

Internet Links for Eugsterite

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  • Raman and XRD data at RRUFF project
  • American Mineralogist Crystal Structure Database
  • Search for Eugsterite in the Natural History Museum (London) online catalogue
  • Eugsterite details from Handbook of Mineralogy (PDF)
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    Localities for Eugsterite

    Show Locality List (8 Items)
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