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Microcline

A valid IMA mineral species - grandfathered
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About MicroclineHide

Formula:
K(AlSi3O8)
Colour:
White, grey, greyish yellow, yellowish, tan, salmon-pink, bluish green, green.
Lustre:
Vitreous
Hardness:
6 - 6½
Specific Gravity:
2.54 - 2.57
Crystal System:
Triclinic
Name:
Name given in 1830 by Johann Friedrich August Breithaupt to a reddish to brownish feldspar from Arendal, Norway, and a feldspar with bluish schiller from Stavern (formerly Fredrichsvärn), Norway, from the Greek μικρός (little) and κλινειν (to incline), in allusion to the small departure from monoclinic symmetry.
Feldspar Group.
K-feldspar with fully ordered Al and Si distribution.

A fully ordered member of the K-feldspar structural series, which extends between disordered, monoclinic sanidine through partially ordered orthoclase to completely ordered, triclinic microcline.

Although petrologists have long used microscopic twinning and other optical properties as a method of distinguishing orthoclase, microcline and sanidine, Wright and Stewart (1958) used the position of certain d values in XRD patterns to calculate the degree of disorder of a K-feldspar (plus it’s Na content) and thus have a more quantitative method to identify its structural state.

Microcline forms in more slowly cooled rocks like granite pegmatites, whilst Sanidine forms in rapidly cooled volcanic rocks (eg. Rhyolite) and some high level intrusive dykes. Orthoclase is the most common member of the series, being the dominant K-feldspar in most granite and other plutonic rocks, with an intermediate cooling regime. Microcline constitutes some hydrothermal “adularia” (some is orthoclase).




Unique IdentifiersHide

Mindat ID:
2704
Long-form identifier:
mindat:1:1:2704:1
GUID
(UUID V4):
f1f915da-855a-4f41-b3d6-84541ce20725

IMA Classification of MicroclineHide

Approved, 'Grandfathered' (first described prior to 1959)

Classification of MicroclineHide

9.FA.30

9 : SILICATES (Germanates)
F : Tektosilicates without zeolitic H2O
A : Tektosilicates without additional non-tetrahedral anions
76.1.1.5

76 : TECTOSILICATES Al-Si Framework
1 : Al-Si Framework with Al-Si frameworks
16.3.5

16 : Silicates Containing Aluminum and other Metals
3 : Aluminosilicates of K

Mineral SymbolsHide

As of 2021 there are now IMA–CNMNC approved mineral symbols (abbreviations) for each mineral species, useful for tables and diagrams.

Please only use the official IMA–CNMNC symbol. Older variants are listed for historical use only.

SymbolSourceReference
MccIMA–CNMNCWarr, L.N. (2021). IMA–CNMNC approved mineral symbols. Mineralogical Magazine, 85(3), 291-320. doi:10.1180/mgm.2021.43
McKretz (1983)Kretz, R. (1983) Symbols of rock-forming minerals. American Mineralogist, 68, 277–279.
McSiivolam & Schmid (2007)Siivolam, J. and Schmid, R. (2007) Recommendations by the IUGS Subcommission on the Systematics of Metamorphic Rocks: List of mineral abbreviations. Web-version 01.02.07. IUGS Commission on the Systematics in Petrology. download
McWhitney & Evans (2010)Whitney, D.L. and Evans, B.W. (2010) Abbreviations for names of rock-forming minerals. American Mineralogist, 95, 185–187 doi:10.2138/am.2010.3371
McThe Canadian Mineralogist (2019)The Canadian Mineralogist (2019) The Canadian Mineralogist list of symbols for rock- and ore-forming minerals (December 30, 2019). download
McWarr (2020)Warr, L.N. (2020) Recommended abbreviations for the names of clay minerals and associated phases. Clay Minerals, 55, 261–264 doi:10.1180/clm.2020.30

Pronunciation of MicroclineHide

Pronunciation:
PlayRecorded byCountry
Jolyon RalphUnited Kingdom

Physical Properties of MicroclineHide

Vitreous
Transparency:
Transparent, Translucent
Comment:
Pearly on cleavage
Colour:
White, grey, greyish yellow, yellowish, tan, salmon-pink, bluish green, green.
Streak:
White
Hardness:
6 - 6½ on Mohs scale
Tenacity:
Brittle
Cleavage:
Perfect
on [001], good on [010]
Parting:
on {100}{110}{110}{201}
Fracture:
Irregular/Uneven
Density:
2.54 - 2.57 g/cm3 (Measured)    2.56 g/cm3 (Calculated)

Optical Data of MicroclineHide

Type:
Biaxial (-)
RI values:
nα = 1.514 - 1.529 nβ = 1.518 - 1.533 nγ = 1.521 - 1.539
2V:
Measured: 66° to 103°, Calculated: 80°
Max Birefringence:
δ = 0.007 - 0.010
Image shows birefringence interference colour range (at 30µm thickness)
and does not take into account mineral colouration.
Surface Relief:
Low
Dispersion:
r > v weak

Chemistry of MicroclineHide

Mindat Formula:
K(AlSi3O8)
Common Impurities:
Fe,Ca,Na,Li,Cs,Rb,H2O,Pb

Age distributionHide

Recorded ages:
Neoarchean to Cretaceous : 2800 Ma to 142.3 ± 1.5 Ma - based on 5 recorded ages.

Crystallography of MicroclineHide

Crystal System:
Triclinic
Class (H-M):
1 - Pinacoidal
Cell Parameters:
a = 8.5784 Å, b = 12.96 Å, c = 7.2112 Å
α = 90.3°, β = 116.05°, γ = 89°
Ratio:
a:b:c = 0.662 : 1 : 0.556
Unit Cell V:
720.16 ų (Calculated from Unit Cell)
Z:
4
Morphology:
Prismatic crystals (to 50 m and 13,500 t), granular, massive. Commonly forms perthitic intergrowths.
Twinning:
Carlsbad, Baveno, Manebach, polysynthetic on albite and pericline laws.
Comment:
Non-standard unit-cell setting (space group C-1, chosen by convention to facilitate comparison with C-centred monoclinic orthoclase and sanidine); reduced cell has the following unit-cell parameters: 7.211, 7.708, 7.833 Å, 113.0, 104.17 103.88° (space group P-1).

Crystallographic forms of MicroclineHide

Crystal Atlas:
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Microcline - Manebach twin
3d models and HTML5 code kindly provided by www.smorf.nl.

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Crystal StructureHide

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IDSpeciesReferenceLinkYearLocalityPressure (GPa)Temp (K)
0000887HyalophaneViswanathan K, Kielhorn H M (1983) Al,Si distribution in a ternary (Ba,K,Na)-feldspar as determined by crystal structure refinement Celsian-rich American Mineralogist 68 122-1241983Yugoslavia0293
0009608HyalophaneDe Pieri R, Quareni S, Hall K M (1977) Refinement of the structures of low and high hyalophanes Acta Crystallographica B33 3073-307619770293
0009609HyalophaneDe Pieri R, Quareni S, Hall K M (1977) Refinement of the structures of low and high hyalophanes Acta Crystallographica B33 3073-307619770293
0000194MicroclineBailey S W (1969) Refinement of an intermediate microcline structure American Mineralogist 54 1540-154519690293
0000714MicroclineRibbe P H (1979) The structure of a strained intermediate microcline in cryptoperthitic association with twinned plagioclase feldspar American Mineralogist 64 402-4081979Kongnat syenite, SW Greenland0293
0000962MicroclineGriffen D T, Johnson B T (1984) Strain in triclinic alkali feldspars: a crystal structure study intermediate American Mineralogist 69 1072-107719840293
0005216MicroclineBlasi A, De Pol Blasi C, Zanazzi P F (1987) A re-examination of the Pellotsalo microcline: Mineralogical implications and genetic considerations The Canadian Mineralogist 25 527-53719870293
0006649MicroclineAllan D R, Angel R J (1997) A high-pressure structural study of microcline (KAlSi3O8) to 7 GPa European Journal of Mineralogy 9 263-27519970293
0006650MicroclineAllan D R, Angel R J (1997) A high-pressure structural study of microcline (KAlSi3O8) to 7 GPa European Journal of Mineralogy 9 263-27519971.4293
0006651MicroclineAllan D R, Angel R J (1997) A high-pressure structural study of microcline (KAlSi3O8) to 7 GPa European Journal of Mineralogy 9 263-27519972.9293
0006652MicroclineAllan D R, Angel R J (1997) A high-pressure structural study of microcline (KAlSi3O8) to 7 GPa European Journal of Mineralogy 9 263-27519974.4293
0006653MicroclineAllan D R, Angel R J (1997) A high-pressure structural study of microcline (KAlSi3O8) to 7 GPa European Journal of Mineralogy 9 263-27519976.2293
0006654MicroclineAllan D R, Angel R J (1997) A high-pressure structural study of microcline (KAlSi3O8) to 7 GPa European Journal of Mineralogy 9 263-27519977.1293
0020534MicroclineDal Negro A, De Pieri R, Quareni S (1978) The crystal structures of nine K feldspars from the Adamello Massif (Northern Italy) Acta Crystallographica B34 2699-27071978Adamello Massif, Northern Italy0293
0020535MicroclineDal Negro A, De Pieri R, Quareni S (1978) The crystal structures of nine K feldspars from the Adamello Massif (Northern Italy) Acta Crystallographica B34 2699-27071978Adamello Massif, Northern Italy0293
0020536MicroclineDal Negro A, De Pieri R, Quareni S (1978) The crystal structures of nine K feldspars from the Adamello Massif (Northern Italy) Acta Crystallographica B34 2699-27071978Adamello Massif, Northern Italy0293
0020537MicroclineDal Negro A, De Pieri R, Quareni S (1978) The crystal structures of nine K feldspars from the Adamello Massif (Northern Italy) Acta Crystallographica B34 2699-27071978Adamello Massif, Northern Italy0293
0020538MicroclineDal Negro A, De Pieri R, Quareni S (1978) The crystal structures of nine K feldspars from the Adamello Massif (Northern Italy) Acta Crystallographica B34 2699-27071978Adamello Massif, Northern Italy0293
0020539MicroclineDal Negro A, De Pieri R, Quareni S (1978) The crystal structures of nine K feldspars from the Adamello Massif (Northern Italy) Acta Crystallographica B34 2699-27071978Adamello Massif, Northern Italy0293
CIF Raw Data - click here to close

Epitaxial Relationships of MicroclineHide

Epitaxial Minerals:
AlbiteNa(AlSi3O8)

X-Ray Powder DiffractionHide

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Radiation - Copper Kα
Data Set:
Data courtesy of RRUFF project at University of Arizona, used with permission.
Powder Diffraction Data:
d-spacingIntensity
4.22 Å(100)
3.26 Å(80)
3.25 Å(80)
3.29 Å(60)
3.70 Å(40)
3.37 Å(40)
3.24 Å(40)
Comments:
Vigo, Galacia, Spain. ICDD 19-926.

Geological EnvironmentHide

Paragenetic Mode(s):
Paragenetic ModeEarliest Age (Ga)
Stage 4a: Earth’s earliest continental crust>4.4-3.0
19 : Granitic intrusive rocks
Near-surface Processes
24 : Authigenic minerals in terrestrial sediments (see also #17)
26 : Hadean detrital minerals
Stage 4b: Highly evolved igneous rocks>3.0
34 : Complex granite pegmatites
35 : Ultra-alkali and agpaitic igneous rocks
Geological Setting:
Plutonic felsic rocks, pegmatites, high-grade metamorphic veins, hydrothermal veins

Type Occurrence of MicroclineHide

Synonyms of MicroclineHide

Other Language Names for MicroclineHide

Finnish:Mikrokliini
French:Microcline
Italian:Microclino
Japanese:微斜長石
Lithuanian:Mikroklinas
Polish:Mikroklin
Portuguese:Microclina
Simplified Chinese:微斜长石
Swedish:Mikroklin
Traditional Chinese:微斜長石

Varieties of MicroclineHide

AmazoniteA green to blue-green variety of K-feldspar, usually microcline, but sometimes applied to orthoclase.

The color is usually caused by an elevated content of Pb (up to 1.2% PbO, see list of references).
However, there are also indications that the green c...
ChesterliteWhite, smooth, feebly lustrous crystals.

Originally described from the Poorhouse Quarry, West Bradford, Chester Co., Pennsylvania, USA.
Ferruginous MicroclineA Fe-rich variety of Microcline
HyalophaneCelsian-Hyalophane Series , and the Hyalophane-Orthoclase Series (intermediate member).

Originally reported from Lengenbach Quarry, Im Feld (Imfeld; Feld; Fäld), Binn Valley, Wallis (Valais), Switzerland.

Common AssociatesHide

Associated Minerals Based on Photo Data:
1,349 photos of Microcline associated with Smoky QuartzSiO2
1,264 photos of Microcline associated with QuartzSiO2
1,176 photos of Microcline associated with AlbiteNa(AlSi3O8)
821 photos of Microcline associated with MuscoviteKAl2(AlSi3O10)(OH)2
651 photos of Microcline associated with AegirineNaFe3+Si2O6
640 photos of Microcline associated with SpessartineMn2+3Al2(SiO4)3
469 photos of Microcline associated with FluoriteCaF2
397 photos of Microcline associated with SchorlNaFe2+3Al6(Si6O18)(BO3)3(OH)3(OH)
314 photos of Microcline associated with AquamarineBe3Al2Si6O18
255 photos of Microcline associated with CleavelanditeNa(AlSi3O8)

Related Minerals - Strunz-mindat GroupingHide

9.FA.HexacelsianBaAl2Si2O8Hex. 6/mmm (6/m 2/m 2/m) : P63/mcm
9.FA.Wodegongjieite KCa3(Al7Si9)O32Hex. 6/mmm (6/m 2/m 2/m) : P6/mcc
9.FA.05KaliophiliteKAlSiO4Trig. 3 : P3
9.FA.05KalsiliteKAlSiO4Hex. 6 2 2 : P63 2 2
9.FA.05NephelineNa3K(Al4Si4O16)Hex. 6 : P63
9.FA.05Panunzite(K,Na)AlSiO4Hex. 6 : P63
9.FA.05TrikalsiliteK2NaAl3(SiO4)3Hex. 6 : P63
9.FA.05Yoshiokaite(Ca,Na)[Al(Al,Si)O4]Trig. 3 : P3
9.FA.05CarnegieiteNaAlSiO4Tric.
9.FA.05 vaGermanate-nepheline(Na,K)AlGeO4
9.FA.05MegakalsiliteKAlSiO4Hex. 6 : P63
9.FA.05TrinephelineNaAlSiO4 Hex. 6 : P61
9.FA.05Davidsmithite(Ca,◻)2Na6Al8Si8O32Hex. 6 : P63
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.30Buddingtonite(NH4)(AlSi3O8)Mon. 2 : P21
9.FA.30CelsianBa(Al2Si2O8)Mon. 2/m
9.FA.30OrthoclaseK(AlSi3O8)Mon. 2/m : B2/m
9.FA.30SanidineK(AlSi3O8)Mon. 2/m : B2/m
9.FA.30RubiclineRb(AlSi3O8)Mon. 2/m : B2/m
9.FA.30 vaGermanate-celsianBaAl2Ge2O8
9.FA.30MonalbiteNaAlSi3O8Mon. 2/m : B2/m
9.FA.30FerrisanidineK[Fe3+Si3O8]Mon. 2/m : B2/m
9.FA.35AlbiteNa(AlSi3O8)Tric. 1
9.FA.35AnorthiteCa(Al2Si2O8)Tric. 1 : P1
9.FA.35ReedmergneriteNaBSi3O8Tric. 1 : P1
9.FA.40ParacelsianBa(Al2Si2O8)Mon. 2/m : P21/b
9.FA.45SvyatoslaviteCa(Al2Si2O8)Mon. 2 : P21
9.FA.45KumdykoliteNa(AlSi3O8)Orth. mmm (2/m 2/m 2/m) : Pnnm
9.FA.50SlawsoniteSr(Al2Si2O8)Mon. 2/m : P21/b
9.FA.55LisetiteCaNa2Al4Si4O16Orth. mm2
9.FA.60BanalsiteNa2BaAl4Si4O16Orth. mm2 : Iba2
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.65PekoviteSrB2Si2O8Orth. mmm (2/m 2/m 2/m) : Pnma
9.FA.70StöffleriteCaAl2Si2O8Tet. 4/m : I4/m
9.FA.70Lingunite(Na,Ca)AlSi3O8Tet. 4/m : I4/m
9.FA.70LiebermanniteKAlSi3O8Tet. 4/m : I4/m
9.FA.75KokchetaviteK(AlSi3O8)Hex. 6/mmm (6/m 2/m 2/m) : P6/mcc
9.FA.75Pfaffenbergite KNa3(Al4Si12)O32Hex. 6/mmm (6/m 2/m 2/m) : P6/mcc

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.
Industrial Uses:
Ceramics

Microcline in petrologyHide

Internet Links for MicroclineHide

References for MicroclineHide

Reference List:

Localities for MicroclineHide

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.

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