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Gearksutite

Big Photo

Kara-Oba W deposit, Betpakdala Desert (Bet-Pak-Dal Desert), Qaraghandy Oblysy (Karaganda Oblast'), Kazakhstan
© Pavel M. Kartashov

Show Gearksutite Photos (15)
Formula:
Ca[Al(F,OH)
 
5
(H
 
2
O)]
System:TriclinicColour:white, colourless ...
Hardness:2
Name:From the Greek γή, earth, and arksutite (chiolite), which it was thought to resemble in composition, in allusion to the earthy character of the material.


A complex aluminium salt. One of the last formed secondary fluorides at Ivigtut.

Classification of Gearksutite

IMA status:Approved
Strunz 8th edition ID:3/C.01-10
Nickel-Strunz 10th (pending) edition ID:3.CC.05

3 : HALIDES
C : Complex halides
C : Soro-aluminofluorides
Dana 8th edition ID:11.6.8.1

11 : HALIDE COMPLEXES
6 : Aluminofluorides - Isolated Octahedra
Hey's CIM Ref.:8.6.12

8 : Halides - Fluorides, Chlorides, Bromides and Iodides; also Fluoborates and Fluosilicates
6 : Halides of Al
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Type Occurrence of Gearksutite

Type Locality:Ivigtut Cryolite deposit, Ivittuut (Ivigtut), Arsuk Firth, Arsuk, Kitaa (West Greenland) Province, Greenland
Year of Discovery:1868

Physical Properties of Gearksutite

Lustre:Dull
Colour:white, colourless (including in transmitted light)
Streak:white
Hardness (Mohs):2
Cleavage:Imperfect/Fair
On {1-10}.
Density (measured):2.768 g/cm3
Density (calculated):2.771 g/cm3

Crystallography of Gearksutite

Crystal System:Triclinic
Class (H-M):1 - Pinacoidal
Space Group:P1
Cell Parameters:a = 4.94Å, b = 6.81Å, c = 6.978Å
α = 101.12°, β = 94.86°, γ = 110.07°
Ratio:a:b:c = 0.725 : 1 : 1.025
Unit Cell Volume:V 213.43 ų
Z:2
Morphology:Massive; nodular with an earthy to chalky character. Consisting of very minute needles with inclined extinction.
X-Ray Powder Diffraction:
Image Loading

Radiation - Copper Kα
Data Set:
Horizontal Axis: ° to ° Vertical Axis: % Source Data: Filtered Data: Peaks:
Data courtesy of RRUFF project at University of Arizona, used with permission.

Optical Data of Gearksutite

Type:Biaxial (-)
RI values: nα = 1.448 nβ = 1.454 nγ = 1.456
Maximum Birefringence:δ = 0.008

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

Chemical Properties of Gearksutite

Formula:
Ca[Al(F,OH)
 
5
(H
 
2
O)]
Essential elements:Al, Ca, F, H, O
All elements listed in formula:Al, Ca, F, H, O

Relationship of Gearksutite to other Species

Related Minerals - Nickel-Strunz Grouping):

- +
3.CC.10Acuminite
Sr[AlF
 
4
(OH)(H
 
2
O)]
3.CC.10Tikhonenkovite
Sr[AlF
 
4
(OH)(H
 
2
O)]
3.CC.15Artroeite
Pb[AlF
 
3
(OH)
 
2
]
3.CC.20Calcjarlite
Na(Ca,Sr)
 
3
Al
 
3
(OH)
 
2
F
 
14
3.CC.20Jarlite
Na(Sr,Na)
 
7
MgAl
 
6
F
 
32
(OH,H
 
2
O)
 
2
3.CC.20Jørgensenite
Na
 
2
(Sr,Ba)
 
14
Na
 
2
Al
 
12
F
 
64
(OH,F)
 
4
Related Minerals - Hey's Index Grouping:

- +
8.6.1Zharchikhite
AlF(OH)
 
2
8.6.2Chloraluminite
AlCl
 
3
·6H
 
2
O
8.6.3Cadwaladerite
Al(OH)
 
2
Cl·4H
 
2
O
8.6.4Cryolithionite
Na
 
3
Li
 
3
[AlF
 
6
]
 
2
8.6.5Cryolite
Na
 
3
[AlF
 
6
]
8.6.6Chiolite
Na
 
5
Al
 
3
F
 
14
8.6.7Elpasolite
NaK
 
2
[AlF
 
6
]
8.6.8Weberite
Na
 
2
Mg[F|AlF
 
6
]
8.6.9Ralstonite
NaMgAl(F,OH)
 
6
·H
 
2
O
8.6.10Koenenite
Na
 
4
Mg
 
9
Al
 
4
Cl
 
12
(OH)
 
22
8.6.11 Chlor-manasseite
Mg
 
x
Al(OH)
 
2x+2
Cl·(x-0.8)H
 
2
O x about 1.75
8.6.13Prosopite
CaAl
 
2
(F,OH)
 
8
8.6.14Yaroslavite
Ca
 
3
Al
 
2
F
 
10
(OH)
 
2
·H
 
2
O
8.6.15Carlhintzeite
Ca
 
2
[F|AlF
 
6
] · H
 
2
O
8.6.16Colquiriite
CaLi[AlF
 
6
]
8.6.17Thomsenolite
NaCaAlF
 
6
·H
 
2
O
8.6.18Pachnolite
NaCaAlF
 
6
·H
 
2
O
8.6.19Zirklerite
(Fe,Mg,Ca)
 
9
Al
 
4
Cl
 
18
(OH)
 
12
·14H
 
2
O (?)

Other Names for Gearksutite

Synonyms:
EvigtokiteParagearksutite
Other Languages:
German:Gearksutit
Russian:Геарксутит
Spanish:Gearksutita

Other Information

Other Information:Readily soluble in dilute acid.
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 Gearksutite

Reference List:Hagemann in: Dana, J.D. (1868) System of Mineralogy, 5th. Edition, New York: 130.

Flight (1883) Journal of the Chemical Society: 43: 140 (as Evigtokite).

Cross and Hillebrand (1885) USGS Bulletin 20: 59.

Dana, E.S. (1892) System of Mineralogy, 6th. Edition, New York: 181.

Larsen, E. and Wells (1916) Proceedings of the National Academy of Sciences: 2: 360.

Simpson (1920) Mineralogical Magazine: 19: 23.

Larsen, E.S. (1921) The Microscopic Determination of the Nonopaque Minerals, First edition, USGS Bulletin 679: 78.

Henderson (1929) American Mineralogist: 14: 281.

Smolyaninov and Isakov (1946) Belyankin Jubilee volume, Academy of Sciences, USSR: 145 (as Paragearksutite).

Palache, C., Berman, H., & Frondel, C. (1951), The System of Mineralogy of James Dwight Dana and Edward Salisbury Dana, Yale University 1837-1892, Volume II: Halides, Nitrates, Borates, Carbonates, Sulfates, Phosphates, Arsenates, Tungstates, Molybdates, Etc. John Wiley and Sons, Inc., New York, 7th edition, revised and enlarged: 119-120.

American Mineralogist (2000): 85: 231-235.

Internet Links for Gearksutite

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    Localities for Gearksutite

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