Douglasite
A valid IMA mineral species - grandfathered
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Formula:
K2[Fe2+Cl4(OH2)2]
Colour:
Light green; brownish red on exposure.
Lustre:
Vitreous
Specific Gravity:
2.16
Crystal System:
Monoclinic
Name:
For the type locality, Douglashall near Westeregeln, Saxony, Germany.
This page provides mineralogical data about Douglasite.
Unique Identifiers
Mindat ID:
1314
Long-form identifier:
mindat:1:1:1314:3
GUID
(UUID V4):
(UUID V4):
19b6b17f-b0aa-4ed9-897e-ae4fc4427364
IMA Classification of Douglasite
Approved, 'Grandfathered' (first described prior to 1959)
IMA Formula:
K2Fe2+Cl4 · 2H2O
Classification of Douglasite
3.CJ.20
3 : HALIDES
C : Complex halides
J : With MX6 complexes; M = Fe, Mn, Cu
3 : HALIDES
C : Complex halides
J : With MX6 complexes; M = Fe, Mn, Cu
11.3.1.1
11 : HALIDE COMPLEXES
3 : AmBX4·xH2O
11 : HALIDE COMPLEXES
3 : AmBX4·xH2O
8.11.4
8 : Halides - Fluorides, Chlorides, Bromides and Iodides; also Fluoborates and Fluosilicates
11 : Halides of Fe and Ni
8 : Halides - Fluorides, Chlorides, Bromides and Iodides; also Fluoborates and Fluosilicates
11 : Halides of Fe and Ni
Mineral Symbols
As of 2021 there are now IMA–CNMNC approved mineral symbols (abbreviations) for each mineral species, useful for tables and diagrams.
Symbol | Source | Reference |
---|---|---|
Dgl | IMA–CNMNC | Warr, L.N. (2021). IMA–CNMNC approved mineral symbols. Mineralogical Magazine, 85(3), 291-320. doi:10.1180/mgm.2021.43 |
Physical Properties of Douglasite
Vitreous
Transparency:
Translucent
Colour:
Light green; brownish red on exposure.
Density:
2.16 g/cm3 (Measured) 2.04 g/cm3 (Calculated)
Optical Data of Douglasite
Type:
Biaxial (+)
RI values:
nα = 1.488 nβ = 1.488 nγ = 1.500
2V:
Measured: 5°
Max Birefringence:
δ = 0.012
Image shows birefringence interference colour range (at 30µm thickness)
and does not take into account mineral colouration.
and does not take into account mineral colouration.
Surface Relief:
Moderate
Chemistry of Douglasite
Mindat Formula:
K2[Fe2+Cl4(OH2)2]
Crystallography of Douglasite
Crystal System:
Monoclinic
Class (H-M):
2/m - Prismatic
Cell Parameters:
a = 11.80 Å, b = 16.27 Å, c = 8.225 Å
β = 104.89°
β = 104.89°
Ratio:
a:b:c = 0.725 : 1 : 0.506
Unit Cell V:
1526 ų
Z:
6
Morphology:
Coarsely granular masses.
Comment:
Space Group: n.d.
X-Ray Powder Diffraction
Powder Diffraction Data:
d-spacing | Intensity |
---|---|
3.081 Å | (100) |
3.665 Å | (78) |
4.032 Å | (62) |
4.157 Å | (59) |
2.9678 Å | (53) |
5.065 Å | (47) |
2.3700 Å | (41) |
Geological Environment
Paragenetic Mode(s):
Paragenetic Mode | Earliest Age (Ga) |
---|---|
Near-surface Processes | |
25 : Evaporites (prebiotic) |
Type Occurrence of Douglasite
General Appearance of Type Material:
Coarsely granular masses.
Place of Conservation of Type Material:
The Natural History Museum, London, England, 1965,450.
Associated Minerals at Type Locality:
Reference:
Precht H (1880) Ueber die bildung des wasserstoffs in den Stassfurter kalisalzbergweken. Berichte der Deutschen Chemischen Gesellschaft 13, 2326-2328
Other Language Names for Douglasite
Related Minerals - Strunz-mindat Grouping
3.CJ.05 | Chlormanganokalite | K4[MnCl6] |
3.CJ.05 | Rinneite | K3Na[FeCl6] |
3.CJ.05 | Saltonseaite | K3NaMnCl6 |
3.CJ.10 | Erythrosiderite | K2[Fe3+Cl5(H2O)] |
3.CJ.10 | Kremersite | (NH4,K)2[Fe3+Cl5(H2O)] |
3.CJ.15 | Mitscherlichite | K2CuCl4 · 2H2O |
3.CJ.25 | Redikortsevite | (NH4)MgCl3 · 6H2O |
3.CJ.30 | Zirklerite | (Fe,Mg,Ca)9Al4Cl18(OH)12 · 14H2O (?) |
3.CJ.30 | Kalithallite | K3Tl3+Cl6 · 2H2O |
Other Information
Health Risks:
No information on health risks for this material has been entered into the database. You should always treat mineral specimens with care.
Internet Links for Douglasite
mindat.org URL:
https://www.mindat.org/min-1314.html
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References for Douglasite
Reference List:
Precht, H. (1880) Ueber die Bildung des Wasserstoffs in den Stassfurter Kalisalzbergwerken. Berichte der deutschen chemischen Gesellschaft, 13 (2) 2326-2328 doi:10.1002/cber.188001302262
Localities for Douglasite
Locality List
- This locality has map coordinates listed.
- This locality has estimated coordinates.
ⓘ - Click for references and further information on this occurrence.
? - Indicates mineral may be doubtful at this locality.
- Good crystals or important locality for species.
- World class for species or very significant.
(TL) - Type Locality for a valid mineral species.
(FRL) - First Recorded Locality for everything else (eg varieties).
Struck out - Mineral was erroneously reported from this locality.
Faded * - Never found at this locality but inferred to have existed at some point in the past (e.g. from pseudomorphs).
All localities listed without proper references should be considered as questionable.
All localities listed without proper references should be considered as questionable.
Canada | |
| Elmi Assadzadeh (2014) |
| Battler et al. (2013) |
Germany (TL) | |
| Precht (1880) |
Poland | |
| Wachowiak et al. (2016) |
| Jeff Weissman / Photographic Guide to ... |