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Labradorite

Formula:
(Ca,Na)[Al(Al,Si)Si
 
2
O
 
8
]
Colour:Pale green, blue, ...Hardness:6 - 6½
Name:From the occurrence in Labrador, Canada.
A variety of Anorthite

A Plagioclase Feldspar with an Albite : Anorthite molar ratio ranging from 30 : 70 to 50 : 50. An intermediate member of the Albite-Anorthite Series.

Classification of Labradorite

Strunz 8th edition ID:8/J.07-50
Nickel-Strunz 10th (pending) edition ID:9.FA.35

9 : SILICATES (Germanates)
F : Tektosilicates without zeolitic H2O
A : Tektosilicates without additional non-tetrahedral anions
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Physical Properties of Labradorite

Lustre:Sub-Vitreous
Colour:Pale green, blue, colourless, grey-white
Streak:White
Hardness (Mohs):6 - 6½
Cleavage:Perfect
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 Labradorite

Type:Biaxial (+)
RI values: nα = 1.554 - 1.563 nβ = 1.559 - 1.568 nγ = 1.562 - 1.573
2V:Measured: 85° , Calculated: 78° to 86°
Maximum Birefringence:δ = 0.008 - 0.010

Chart shows birefringence interference colour range (at 30µm thickness) and does not take into account mineral colouration.
Surface Relief:Low
Dispersion:none

Chemical Properties of Labradorite

Formula:
(Ca,Na)[Al(Al,Si)Si
 
2
O
 
8
]
Essential elements:Al, Ca, O, Si
All elements listed in formula:Al, Ca, Na, O, Si

Relationship of Labradorite to other Species

Member of Group:
Feldspar Group:
Related Minerals - Nickel-Strunz Grouping):

- +
9.FA.05Kaliophilite
K[AlSiO
 
4
]
9.FA.05Kalsilite
K[AlSiO
 
4
]
9.FA.05Nepheline
(Na,K)[AlSiO
 
4
]
9.FA.05Panunzite
(Na,K)[AlSiO
 
4
]
9.FA.05Trikalsilite
(Na,K)[AlSiO
 
4
]
9.FA.05Yoshiokaite
(Ca,Na)[Al(Al,Si)O
 
4
]
9.FA.05Megakalsilite
KAlSiO
 
4
9.FA.10Malinkoite
NaBSiO
 
4
9.FA.15Virgilite
LiAlSi
 
2
O
 
6
9.FA.25Lisitsynite
KBSi
 
2
O
 
6
9.FA.30Adularia
KAlSi
 
3
O
 
8
9.FA.30Anorthoclase
(Na,K)[AlSi
 
3
O
 
8
]
9.FA.30Buddingtonite
(NH
 
4
)[AlSi
 
3
O
 
8
]
9.FA.30Celsian
Ba[Al
 
2
Si
 
2
O
 
8
]
9.FA.30Hyalophane
(K,Ba)[Al(Si,Al)Si
 
2
O
 
8
]
9.FA.30Microcline
K[AlSi
 
3
O
 
8
]
9.FA.30Orthoclase
K[AlSi
 
3
O
 
8
]
9.FA.30Sanidine
K[AlSi
 
3
O
 
8
]
9.FA.30Rubicline
(Rb,K)[AlSi
 
3
O
 
8
]
9.FA.30Monalbite
Na[AlSi
 
3
O
 
8
]
9.FA.35Albite
Na[AlSi
 
3
O
 
8
]
9.FA.35Andesine
(Na,Ca)[Al(Si,Al)Si
 
2
O
 
8
]
9.FA.35Anorthite
Ca[Al
 
2
Si
 
2
O
 
8
]
9.FA.35Bytownite
(Ca,Na)[Al(Al,Si)Si
 
2
O
 
8
]
9.FA.35Oligoclase
(Na,Ca)[Al(Si,Al)Si
 
2
O
 
8
]
9.FA.35Reedmergnerite
Na[BSi
 
3
O
 
8
]
9.FA.40Paracelsian
Ba[Al
 
2
Si
 
2
O
 
8
]
9.FA.45Svyatoslavite
Ca[Al
 
2
Si
 
2
O
 
8
]
9.FA.45Kumdykolite
NaAlSi
 
3
O
 
8
9.FA.50Slawsonite
(Sr,Ca)[Al
 
2
Si
 
2
O
 
8
]
9.FA.55Lisetite
CaNa
 
2
Al
 
4
Si
 
4
O
 
16
9.FA.60Banalsite
BaNa
 
2
[Al
 
2
Si
 
2
O
 
8
]
 
2
9.FA.60Stronalsite
SrNa
 
2
[Al
 
2
Si
 
2
O
 
8
]
 
2
9.FA.65Danburite
CaB
 
2
Si
 
2
O
 
8
9.FA.65Maleevite
BaB
 
2
Si
 
2
O
 
8
9.FA.65Pekovite
SrB
 
2
Si
 
2
O
 
8
9.FA.70Lingunite
(Na,Ca)AlSi
 
3
O
 
8
9.FA.75Kokchetavite
KAlSi
 
3
O
 
8

Other Names for Labradorite

Synonyms:
Black MoonstoneCarnatiteLabrador FeldsparLabrador MoonstoneMauilite
Opaline FeldsparRadauiteSiliciteSpectrolite
Other Languages:
Czech:Labradorit
Dutch:Labradoriet
Finnish:Labradoriitti
French:Labradorite
German:Labradorit
Carnatit
Mauilit
Radauit
Silicit
Spectrolith
Spektrolith
Hebrew:לברדוריט
Italian:Labradorite
Japanese:ラブラドル長石
Lithuanian:Labradoritas
Norwegian (Bokmål):Labrador
Polish:Labrador
Portuguese:Labradorite
Russian:Лабрадорит
Slovak:Labradorit
Spanish:Labradorita
Carnatita
Mauilita
Radauita
Silicita
Spectrolita
Ukrainian:Лабрадорит
Varieties:
Lynx Eye

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 Labradorite

Reference List:Rose. G. (1823): Über den Feldspat, Albit, Labradorit und Anorthit, Annalen der Physik und Chemie, Vol. 73/NF-43, 175-208.

Acta Crystallographica (1988): B44: 344.

Internet Links for Labradorite

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  • External Links:
  • Labradorite details from Handbook of Mineralogy (PDF)
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    Localities for Labradorite

    The 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.
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    Copyright © Jolyon Ralph and Ida Chau 1993-2009. Site Map. Locality, mineral & photograph data are the copyright of the individuals who submitted them.Further information contact the Site hosted & developed by Jolyon Ralph. Mindat.org is an online information resource dedicated to providing free mineralogical information to all. Mindat relies on the contributions of hundreds of members and supporters. If you would like to add information to improve the quality of our database, then click here to register. Current server date and time: 28th Oct 2009 17:27:34