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Rokühnite

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Salzdetfurth Potash Works, Hildesheim, Lower Saxony, Germany
© 2008, J. Weissman

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, Groß 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
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
8.11.2 Hydromolysite
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
(OH
 
2
)]
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
 
4
Fe(OH)
 
8
OCl·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
German names:
Rokühnit
Russian names:
Рокюнит
Spanish names:
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.

Articles/Blogs about Rokühnite

Internet Links for Rokühnite

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  • Raman and XRD data at RRUFF project
  • American Mineralogist Crystal Structure Database
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    Localities for Rokühnite

    (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
        • Groß Giesen
    		Aufschluss 1987(4), 114
    Aufschluss 87/4
    Mineral and/or Locality
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