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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
Diaphaneity (Transparency):Translucent on thin edges
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

Related Minerals - Nickel-Strunz Grouping):
9.FA.IMA2007-049
NaAlSi
 
3
O
 
8
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.30Kokchetavite
KAlSi
 
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.35Lingunite
(Na,Ca)AlSi
 
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.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
Ca[BSiO
 
4
]
 
2
9.FA.65Maleevite
BaB
 
2
Si
 
2
O
 
8
9.FA.65Pekovite
SrB
 
2
Si
 
2
O
 
8

Other Names for Labradorite

Synonyms:
Black MoonstoneCarnatiteLabrador FeldsparLabrador MoonstoneMauilite
Opaline FeldsparRadauiteSiliciteSpectrolite
German names:
CarnatitLabradoritMauilitRadauitSilicit
SpectrolithSpektrolith
Russian names:
Лабрадорит
Spanish names:
CarnatitaLabradoritaMauilitaRadauitaSilicita
Spectrolita
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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    Localities for Labradorite

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