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Douglasite

Formula:
K
 
2
[Fe
2+
 
Cl
 
4
(OH
 
2
)
 
2
]
System:MonoclinicColour:Light green; brownish ...
Lustre:Vitreous
Name:For the type locality, Douglashall near Westeregeln, Saxony, Germany.
This page provides mineralogical data about Douglasite.

Classification of Douglasite

IMA status:Valid - first described prior to 1959 (pre-IMA) - "Grandfathered"
Strunz 8th edition ID:3/C.07-20
Nickel-Strunz 10th (pending) edition ID:3.CJ.20

3 : HALIDES
C : Complex halides
J : With MX6 complexes; M = Fe, Mn, Cu
Dana 8th edition ID:11.3.1.1

11 : HALIDE COMPLEXES
3 : AmBX4·xH2O
Hey's CIM Ref.:8.11.4

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

Type Locality:Douglashall, Westeregeln, Stassfurt Potash deposit, Saxony-Anhalt, Germany
General Appearance of Type Material:Coarsely granular masses.
Year of Discovery:1880
Associated Minerals at type locality:
SylviteHaliteCarnallite

Physical Properties of Douglasite

Lustre:Vitreous
Colour:Light green; brownish red on exposure.
Density (calculated):2.04 g/cm3

Crystallography of Douglasite

Crystal System:Monoclinic
Cell Parameters:a = 11.8Å, b = 16.27Å, c = 8.225Å
β = 104.89°
Ratio:a:b:c = 0.725 : 1 : 0.506
Unit Cell Volume:V 1526 ų
Z:6
Morphology:Coarsely granular masses.

Optical Data of Douglasite

Type:Biaxial (+)
RI values: nα = 1.488 nβ = 1.488 nγ = 1.500
2V:Measured: 5°
Maximum Birefringence:δ = 0.012

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

Chemical Properties of Douglasite

Formula:
K
 
2
[Fe
2+
 
Cl
 
4
(OH
 
2
)
 
2
]
Essential elements:Cl, Fe, H, K, O
All elements listed in formula:Cl, Fe, H, K, O

Relationship of Douglasite to other Species

Related Minerals - Nickel-Strunz Grouping):

- +
3.CJ.05Chlormanganokalite
K
 
4
[MnCl
 
6
]
3.CJ.05Rinneite
K
 
3
Na[FeCl
 
6
]
3.CJ.10Erythrosiderite
K
 
2
[Fe
3+
 
Cl
 
5
(OH
 
2
)]
3.CJ.10Kremersite
(NH
 
4
,K)
 
2
[Fe
3+
 
Cl
 
5
(H
 
2
O)]
3.CJ.15Mitscherlichite
K
 
2
[CuCl
 
4
] · 2H
 
2
O
3.CJ.25Redikortsevite
(NH
 
4
)MgCl
 
3
 · 6H
 
2
O
3.CJ.30Zirklerite
(Fe,Mg,Ca)
 
9
Al
 
4
Cl
 
18
(OH)
 
12
·14H
 
2
O (?)
Related Minerals - Hey's Index Grouping:

- +
8.11.1Molysite
FeCl
 
3
8.11.2 Hydromolysite
FeCl
 
3
·6H
 
2
O
8.11.3Rokühnite
FeCl
 
2
·2H
 
2
O
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 Douglasite

Other Languages:
German:Douglasit
Eisenchlorürchlorkalium
Spanish:Douglasita

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 Douglasite

Reference List:Ochsenius (1877) Steinsalzlager, Halle: 94.

Precht, H. (1880): Ueber die Bildung des Wasserstoffs in den Stassfurter Precht Kalisalzbergwerken.- Berichte der Deutschen Chemischen Gesellschaft Berlin 13, 2326-2328.

Boeke (1909) Neues Jahrbuch für Mineralogie, Geologie und Paleontologie, Heidelberg, Stuttgart: II: 44.

Larsen, E.S. (1921) The Microscopic Determination of the Nonopaque Minerals, First edition, USGS Bulletin 679: 69.

Palache, Charles, Harry Berman & Clifford Frondel (1951), The System of Mineralogy of James Dwight Dana and Edward Salisbury Dana Yale University 1837-1892, Seventh edition, Volume II: 100.

Internet Links for Douglasite

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    Localities for Douglasite

    (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
     
    • Saxony-Anhalt
      • Stassfurt Potash deposit
        • Westeregeln
    		H. Precht (1880): Ueber die Bildung des Wasserstoffs in den Stassfurter Kalisalzbergwerken.- Berichte der Deutschen Chemischen Gesellschaft Berlin 13, 2326-2328
    Mineral and/or Locality
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