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Rokühnite

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Formula:
FeCl
 
2
· 2H
 
2
O
Colour:Colourless
Name:Named after Robert Kühn, professor of mineralogy.
This page provides mineralogical data about Rokühnite.

Classification of Rokühnite

IMA status:Approved
Nickel-Strunz 10th (pending) edition ID:3.BB.10

3 : HALIDES
B : Simple halides, with H2O
B : M:X = 1:2
Dana 8th edition ID:9.2.4.1

9 : NORMAL HALIDES
2 : AX2
Hey's CIM Ref.:8.11.3

8 : Halides - Fluorides, Chlorides, Bromides and Iodides; also Fluoborates and Fluosilicates
11 : Halides of Fe and Ni
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Type Occurrence of Rokühnite

Co-type Localities:Siegfried-Giesen Potash Works, Giesen, Hildesheim, Lower Saxony, Germany
Salzdetfurth Potash Works, Hildesheim, Lower Saxony, Germany

Physical Properties of Rokühnite

Diaphaneity (Transparency):Transparent
Colour:Colourless

Optical Data of Rokühnite

Type:Biaxial (+)
RI values: nα = 1.605 nβ = 1.633 nγ = 1.702
2V:Measured: 64° , Calculated: 68°
Maximum Birefringence:δ = 0.097

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

Chemical Properties of Rokühnite

Formula:
FeCl
 
2
· 2H
 
2
O
Simplified for copy/paste:FeCl2·2H2O
Essential elements:Cl, Fe, H, O
All elements listed in formula:Cl, Fe, H, O

Relationship of Rokühnite to other Species

Related Minerals - Nickel-Strunz Grouping):

- +
3.BB.05Eriochalcite
CuCl
 
2
· 2H
 
2
O
3.BB.15Bischofite
MgCl
 
2
· 6H
 
2
O
3.BB.20Nickelbischofite
NiCl
 
2
· 6H
 
2
O
3.BB.25Sinjarite
CaCl
 
2
· 2H
 
2
O
3.BB.30Antarcticite
CaCl
 
2
· 6H
 
2
O
3.BB.35Tachyhydrite
CaMg
 
2
Cl
 
6
· 12H
 
2
O
Related Minerals - Hey's Index Grouping:

- +
8.11.1Molysite
FeCl
 
3
8.11.2Hydromolysite
FeCl
 
3
· 6H
 
2
O
8.11.4Douglasite
K
 
2
[Fe
2+
 
Cl
 
4
(OH
 
2
)
 
2
]
8.11.5Erythrosiderite
K
 
2
[Fe
3+
 
Cl
 
5
(H
 
2
O)]
8.11.6Rinneite
K
 
3
Na[FeCl
 
6
]
8.11.7Kremersite
(NH
 
4
,K)
 
2
[Fe
3+
 
Cl
 
5
(H
 
2
O)]
8.11.8Iowaite
Mg
 
6
Fe
3+
2
(OH)
 
16
Cl
 
2
· 4H
 
2
O
8.11.9Nickelbischofite
NiCl
 
2
· 6H
 
2
O
8.11.10Lawrencite
(Fe
2+
 
,Ni)Cl
 
2

Other Names for Rokühnite

Synonyms:
IMA1979-036
Other Languages:
German:Rokühnit
Russian:Рокюнит
Spanish:Rokühnita

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 Rokühnite

Reference List:

- +
American Mineralogist (1981): 66: 219.

Internet Links for Rokühnite

Search Engines:
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  • External Links:
  • Look for Rokühnite on Webmineral
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  • Look for Rokühnite on Wikipedia
  • Look for Rokühnite on Mineralien Atlas
  • Raman and XRD data at RRUFF project
  • American Mineralogist Crystal Structure Database
  • Rokühnite details from Handbook of Mineralogy (PDF)
  • Mineral Dealers:
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  • Rare and Unusual minerals at Mineralogical Research Company
  • Find Rokühnite on www.crystalclassics.co.uk
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  • Localities for Rokühnite

    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.
    Germany
     
    • Lower Saxony
      • Hildesheim
        • Diekholzen Potash works
    Andreas Gerstenberg collection
        • Giesen
    Aufschluss 1987(4), 114
    Aufschluss 87/4
    Ukraine
     
    • Zhytomyr Oblast' (Zhitomir Oblast')
    Lyckberg, P., Chornousenko, V. & Wilson, W. E. (2009): Volodarsk-Volynski, Zhitomir Oblast, Ukraine. Mineralogical Record, 40, 473-506.
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    Copyright © Jolyon Ralph and Ida Chau 1993-2014. Site Map. Locality, mineral & photograph data are the copyright of the individuals who submitted them. Site hosted & developed by Jolyon Ralph. Mindat.org is an online information resource dedicated to providing free mineralogical information to all. Mindat relies on the contributions of thousands of members and supporters. Mindat does not offer minerals for sale. If you would like to add information to improve the quality of our database, then click here to register.
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