Koktaite (original) (raw)
A valid IMA mineral species - grandfathered
About KoktaiteHide
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Formula:
(NH4)2Ca(SO4)2 · H2O
Crystal System:
Monoclinic
Name:
Named in honor of Jaroslav Kokta (29 April 1904, Skorotice, Austria-Hungary - 2 August 1970, Ostrava, Czechoslovakia), chemist at the Masarykov University, Brno, Czechoslovakia who analyzed the artificial compound.
This page provides mineralogical data about Koktaite.
Unique IdentifiersHide
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Long-form identifier:
mindat:1:1:2237:4
290d0dae-6482-4cfe-8f79-2008301f3074
IMA Classification of KoktaiteHide
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Approved, 'Grandfathered' (first described prior to 1959)
Type description reference:
Classification of KoktaiteHide
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7.CD.35
7 : SULFATES (selenates, tellurates, chromates, molybdates, wolframates)
C : Sulfates (selenates, etc.) without additional anions, with H2O
D : With only large cations
29.3.1.2
29 : HYDRATED ACID AND NORMAL SULFATES
3 : A2B(XO4)2·xH2O
25.4.11
25 : Sulphates
4 : Sulphates of Ca, Sr and Ba
Mineral SymbolsHide
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As of 2021 there are now IMA–CNMNC approved mineral symbols (abbreviations) for each mineral species, useful for tables and diagrams.
| Symbol | Source | Reference |
|---|---|---|
| Kkt | 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 KoktaiteHide
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Transparency:
Transparent, Translucent
Density:
2.09 g/cm3 (Measured) 2.114 g/cm3 (Calculated)
Optical Data of KoktaiteHide
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RI values:
_n_α = 1.524 _n_β = 1.532 _n_γ = 1.536
2V:
Measured: 72° , Calculated: 70°
δ = 0.012
Image shows birefringence interference colour range (at 30µm thickness)
and does not take into account mineral colouration.
Comments:
Y = b; Z' ∧ c (on {110})=2◦
Chemistry of KoktaiteHide
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Mindat Formula:
(NH4)2Ca(SO4)2 · H2O
Crystallography of KoktaiteHide
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Crystal System:
Monoclinic
Class (H-M):
2/m - Prismatic
Cell Parameters:
a = 10.17 Å, b = 7.15 Å, c = 6.34 Å
β = 102.75°
Ratio:
a:b:c = 1.422 : 1 : 0.887
Unit Cell V:
449.65 ų (Calculated from Unit Cell)
Morphology:
Crystals acicular or fibrous-lamellar.
Forms: {100}, {110}, {001}, {011}, {101}
Twinning:
On {100}, common.
X-Ray Powder DiffractionHide
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Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 9.83 Å | (100) |
| 3.30 Å | (65) |
| 4.96 Å | (40) |
| 5.83 Å | (25) |
| 3.00 Å | (25) |
| 3.56 Å | (20) |
| 2.89 Å | (20) |
Geological EnvironmentHide
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Type Occurrence of KoktaiteHide
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General Appearance of Type Material:
Pseudomorphs after gypsum.
Place of Conservation of Type Material:
- Moravian Museum, Brno, Czech Republic, A6109.
- National School of Mines, Paris, France.
- National Museum of Natural History, Washington, D.C., USA, 137963.
Geological Setting of Type Material:
Waste piles of a lignite mine.
Associated Minerals at Type Locality:
Reference:
Sekanina, J. (1948) Koktait, nový nerost ze skupiny syngenitové. Acta Academiae Scientiarum Naturaliuim Moravo-Silesiacae: 20: 1-26.
Synonyms of KoktaiteHide
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Other Language Names for KoktaiteHide
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Common AssociatesHide
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Associated Minerals Based on Photo Data:
Related Minerals - Strunz-mindat GroupingHide
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Other InformationHide
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Notes:
Soluble in H2O, leaving a residue of gypsum.
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 KoktaiteHide
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References for KoktaiteHide
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Reference List:
Localities for KoktaiteHide
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This 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.
Locality ListHide
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- 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.