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Oligoclase

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Formula:
(Na,Ca)[Al(Si,Al)Si2O8]
Colour:
Colourless, white, very pale yellow
Lustre:
Vitreous, Sub-Vitreous
Hardness:
6 - 6½
Specific Gravity:
2.63 - 2.66
Member of:
Name:
Named in 1826 by August Breithaupt from the Greek όλίγος and κλάσις for "little" and fracture alluding to its cleavage.
A variety of Albite

A plagioclase feldspar with an albite : anorthite molar ratio ranging from 90 : 10 to 70 : 30.

Originally described from Danvikstull, Stockholm, Södermanland, Sweden.

Visit gemdat.org for gemological information about Oligoclase.


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Classification of OligoclaseHide

9.FA.35

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

Physical Properties of OligoclaseHide

Vitreous, Sub-Vitreous
Transparency:
Transparent, Translucent
Colour:
Colourless, white, very pale yellow
Comment:
may be green due to inclusions
Streak:
White
Hardness:
6 - 6½ on Mohs scale
Tenacity:
Brittle
Cleavage:
Perfect
{001} perfect, {010} good, {110} poor
Fracture:
Irregular/Uneven, Sub-Conchoidal, Step-Like
Comment:
The angles between the good and perfect cleavages are usually 93-94 degrees
Density:
2.63 - 2.66 g/cm3 (Measured)    2.65 g/cm3 (Calculated)

Chemical Properties of OligoclaseHide

Formula:
(Na,Ca)[Al(Si,Al)Si2O8]

Age informationHide

Age range:
Statherian : 1782.5 ± 3.7 Ma to 1782.5 ± 3.7 Ma - based on data given below.
Sample ages:
Sample IDRecorded ageGeologic TimeDating method
11782.5 ± 3.7 MaStatherian

Chemical AnalysisHide

Oxide wt%:
 1
SiO263.27 %
Al2O323.27 %
MgO0.13 %
CaO3.93 %
MnO0.01 %
FeO0.05 %
Na2O9.23 %
K2O0.19 %
Total:100.08 %
Sample references:
IDLocalityReference
1Beluga sapphire property, Kimmirut, Baffin Island, Nunavut, CanadaBelley, P, et al. (2017) Origin Of Scapolite-Hosted Sapphire (Corundum) Near Kimmirut, Baffin Island, Nunavut, Canada The Canadian Mineralogist,55(4):669 http://dx.doi.org/10.3749/canmin.1700018

Synonyms of OligoclaseHide

Other Language Names for OligoclaseHide

Varieties of OligoclaseHide

Lazur-FeldspathA blue feldspar found with Lapis Lazuli near Lake Baikal, Russia
Oligoclase-AlbiteA variety of Oligoclase with Anorthite:Albite between 80:20 and 90:10. Now regarded as a superflous subdivision of Oligoclase. [Clark, 1993 - "Hey's Mineral Index"]
Originally described from Dypingdal Serpentine-magnesite deposit, Snarum, Modum, Buskeru...

Relationship of Oligoclase to other SpeciesHide

Member of:
Other Members of this group:
AlbiteNa(AlSi3O8)Tric. 1
AmazoniteK(AlSi3O8)
Andesine(Na,Ca)[Al(Si,Al)Si2O8]Tric.
AnorthiteCa(Al2Si2O8)Tric. 1 : P1
Anorthoclase(Na,K)AlSi3O8Tric.
BanalsiteNa2BaAl4Si4O16Orth.
Buddingtonite(NH4)(AlSi3)O8Mon. 2 : P21
Bytownite(Ca,Na)[Al(Al,Si)Si2O8]Tric.
CelsianBa(Al2Si2O8)Mon. 2/m
DmisteinbergiteCa(Al2Si2O8)Hex. 6/mmm (6/m 2/m 2/m) : P6/mmm
FilatoviteK(Al,Zn)2(As,Si)2O8Mon. 2/m
HexacelsianBaAl2Si2O8Hex. 6/mmm (6/m 2/m 2/m) : P63/mcm
Hyalophane(K,Ba)[Al(Si,Al)Si2O8]Mon.
KokchetaviteK(AlSi3O8)Hex. 6/mmm (6/m 2/m 2/m) : P6/mmm
KumdykoliteNa(AlSi3O8)Orth. mmm (2/m 2/m 2/m) : Pnnm
Labradorite(Ca,Na)[Al(Al,Si)Si2O8]
MicroclineK(AlSi3O8)Tric. 1
OrthoclaseK(AlSi3O8)Mon. 2/m : B2/m
ParacelsianBa(Al2Si2O8)Mon.
ReedmergneriteNaBSi3O8Tric.
RubiclineRb(AlSi3O8)Tric.
SanidineK(AlSi3O8)Mon. 2/m : B2/m
SlawsoniteSr(Al2Si2O8)Mon.
StronalsiteNa2SrAl4Si4O16Orth.
SunstoneA variety of feldspar (microcline or oligoclase) that has schiller, commonly with an orange/brown ...
SvyatoslaviteCa(Al2Si2O8)Orth.

Common AssociatesHide

Associated Minerals Based on Photo Data:
Actinolite38 photos of Oligoclase associated with Actinolite on mindat.org.
Titanite19 photos of Oligoclase associated with Titanite on mindat.org.
Calcite11 photos of Oligoclase associated with Calcite on mindat.org.
Epidote10 photos of Oligoclase associated with Epidote on mindat.org.
Prehnite10 photos of Oligoclase associated with Prehnite on mindat.org.
Chlorite Group9 photos of Oligoclase associated with Chlorite Group on mindat.org.
Fluorapatite9 photos of Oligoclase associated with Fluorapatite on mindat.org.
Ilmenite7 photos of Oligoclase associated with Ilmenite on mindat.org.
Hornblende6 photos of Oligoclase associated with Hornblende on mindat.org.
Clinozoisite-Epidote Series6 photos of Oligoclase associated with Clinozoisite-Epidote Series on mindat.org.

Related Minerals - Nickel-Strunz GroupingHide

9.FA.05KaliophiliteKAlSiO4Hex.
9.FA.05KalsiliteKAlSiO4Hex. 6 2 2 : P63 2 2
9.FA.05Nepheline(Na,K)AlSiO4Hex. 6 : P63
9.FA.05Panunzite(K,Na)AlSiO4Hex. 6 : P63
9.FA.05Trikalsilite(K,Na)AlSiO4Hex.
9.FA.05Yoshiokaite(Ca,Na)[Al(Al,Si)O4]Trig. 3 : P3
9.FA.05MegakalsiliteKAlSiO4Hex.
9.FA.10MalinkoiteNaBSiO4Hex. 6 : P63
9.FA.15VirgiliteLiAlSi2O6Hex. 6 2 2 : P62 2 2
9.FA.25LisitsyniteKBSi2O6Orth. 2 2 2 : P2 2 2
9.FA.30AdulariaKAlSi3O8Mon.
9.FA.30Anorthoclase(Na,K)AlSi3O8Tric.
9.FA.30Buddingtonite(NH4)(AlSi3)O8Mon. 2 : P21
9.FA.30CelsianBa(Al2Si2O8)Mon. 2/m
9.FA.30Hyalophane(K,Ba)[Al(Si,Al)Si2O8]Mon.
9.FA.30MicroclineK(AlSi3O8)Tric. 1
9.FA.30OrthoclaseK(AlSi3O8)Mon. 2/m : B2/m
9.FA.30SanidineK(AlSi3O8)Mon. 2/m : B2/m
9.FA.30RubiclineRb(AlSi3O8)Tric.
9.FA.30MonalbiteNaAlSi3O8Mon. 2/m : B2/m
9.FA.35AlbiteNa(AlSi3O8)Tric. 1
9.FA.35Andesine(Na,Ca)[Al(Si,Al)Si2O8]Tric.
9.FA.35AnorthiteCa(Al2Si2O8)Tric. 1 : P1
9.FA.35Bytownite(Ca,Na)[Al(Al,Si)Si2O8]Tric.
9.FA.35Labradorite(Ca,Na)[Al(Al,Si)Si2O8]
9.FA.35ReedmergneriteNaBSi3O8Tric.
9.FA.40ParacelsianBa(Al2Si2O8)Mon.
9.FA.45SvyatoslaviteCa(Al2Si2O8)Orth.
9.FA.45KumdykoliteNa(AlSi3O8)Orth. mmm (2/m 2/m 2/m) : Pnnm
9.FA.50SlawsoniteSr(Al2Si2O8)Mon.
9.FA.55LisetiteCaNa2Al4Si4O16Orth.
9.FA.60BanalsiteNa2BaAl4Si4O16Orth.
9.FA.60StronalsiteNa2SrAl4Si4O16Orth.
9.FA.65DanburiteCaB2Si2O8Orth. mmm (2/m 2/m 2/m)
9.FA.65MaleeviteBaB2Si2O8Orth. mmm (2/m 2/m 2/m) : Pnma
9.FA.65PekoviteSrB2Si2O8
9.FA.70Lingunite(Na,Ca)AlSi3O8Tet. 4/m : I4/m
9.FA.75KokchetaviteK(AlSi3O8)Hex. 6/mmm (6/m 2/m 2/m) : P6/mmm

Fluorescence of OligoclaseHide

Not usually fluorescent in SW UV; may be faint red to faint white.

Other InformationHide

Health Risks:
No information on health risks for this material has been entered into the database. You should always treat mineral specimens with care.

Oligoclase in petrologyHide

References for OligoclaseHide

Reference List:
Sort by Year (asc) | by Year (desc) | by Author (A-Z) | by Author (Z-A)
American Mineralogist (1968): 53: 1709-1723.
Zeitschrift für Kristallographie (1971): 133: 43.

Internet Links for OligoclaseHide

Localities for OligoclaseHide

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 ListShow

Mineral and/or Locality  
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