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Microcline

This page kindly sponsored by Norman King
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
Member of:
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.
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Classification of MicroclineHide

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

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

Chemical Properties of MicroclineHide

Formula:
K(AlSi3O8)
IMA Formula:
KAlSi3O8
Common Impurities:
Fe,Ca,Na,Li,Cs,Rb,H2O,Pb

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 cell-parameters: ~7.22, ~7.62, ~7.92 Å, ~113.1, ~104.2, ~103.7° (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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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.

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.
Chesterlitewhite, smooth, feebly lustrous crystals; originally from the Poorhouse Quarry, West Bradford, Chester Co., Pennsylvania, USA
Ferruginous MicroclineA Fe-rich variety of Microcline
HyalophaneFeldspar Group . Celsian-Hyalophane Series, and the Hyalophane-Orthoclase Series (intermediate member).

Relationship of Microcline 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]
Oligoclase(Na,Ca)[Al(Si,Al)Si2O8]
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 background color, ...
SvyatoslaviteCa(Al2Si2O8)Orth.

Common AssociatesHide

BiotiteA series or subgroup of the Mica Group.
HornblendeAn informal name for dark green to black amphiboles, mostly ferro-hornblende or ...
MuscoviteKAl2(AlSi3O10)(OH)2
QuartzSiO2
Associated Minerals Based on Photo Data:
Smoky Quartz663 photos of Microcline associated with Smoky Quartz on mindat.org.
Quartz546 photos of Microcline associated with Quartz on mindat.org.
Albite422 photos of Microcline associated with Albite on mindat.org.
Muscovite349 photos of Microcline associated with Muscovite on mindat.org.
Aegirine313 photos of Microcline associated with Aegirine on mindat.org.
Spessartine289 photos of Microcline associated with Spessartine on mindat.org.
Fluorite204 photos of Microcline associated with Fluorite on mindat.org.
Schorl149 photos of Microcline associated with Schorl on mindat.org.
Aquamarine113 photos of Microcline associated with Aquamarine on mindat.org.
Cleavelandite106 photos of Microcline associated with Cleavelandite 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.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.35Oligoclase(Na,Ca)[Al(Si,Al)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

Related Minerals - Dana Grouping (8th Ed.)Hide

76.1.1.1OrthoclaseK(AlSi3O8)Mon. 2/m : B2/m
76.1.1.2SanidineK(AlSi3O8)Mon. 2/m : B2/m
76.1.1.3Hyalophane(K,Ba)[Al(Si,Al)Si2O8]Mon.
76.1.1.4CelsianBa(Al2Si2O8)Mon. 2/m
76.1.1.6Anorthoclase(Na,K)AlSi3O8Tric.

Related Minerals - Hey's Chemical Index of Minerals GroupingHide

16.3.1LithositeK6Al4Si8O25 · 2H2OMon.
16.3.2KaliophiliteKAlSiO4Hex.
16.3.3KalsiliteKAlSiO4Hex. 6 2 2 : P63 2 2
16.3.4LeuciteK(AlSi2O6)Tet. 4/m : I41/a
16.3.6OrthoclaseK(AlSi3O8)Mon. 2/m : B2/m
16.3.7SanidineK(AlSi3O8)Mon. 2/m : B2/m
16.3.8MuscoviteKAl2(AlSi3O10)(OH)2Mon. 2/m : B2/b

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

References for MicroclineHide

Reference List:
Sort by Year (asc) | by Year (desc) | by Author (A-Z) | by Author (Z-A)
Breithaupt, A. (1830) Ueber die Felsite und einige neue Specien ihres Geschlechts. Journal für Chemie und Physik: 60: 316-330.
Bachinski, S.W., Müller, G. (1971) Experimental determinations of the microcline-low albite solvus. Journal of Petrology: 1(2): 329-356.
Ferguson, R.B. (1979) Whence orthoclase and microcline? A crystallographer's interpretation of potassium feldspar phase relations. The Canadian Mineralogist: 17: 515-525.
Cherry, M.E., Trembath, L.T. (1979) The disordering of alkali feldspars; I, Dry heating of a microcline perthite. The Canadian Mineralogist: 17: 527-535.
Eggleton, R.A., Buseck, P.R. (1980) The orthoclase-microcline inversion: A high-resolution transmission electron microscope study and strain analysis. Contributions to Mineralogy and Petrology: 74: 123-133.
Fitz Gerald, J.D., McLaren, A.C. (1982) The microstructures of microcline from some granitic rocks and pegmatites. Contributions to Mineralogy and Petrology: 80: 219-229.
(1984) Bulletin de la Société française de Minéralogie et de Cristallographie: 107: 401.
Goldsmith, J. (1988) Enhanced Al/Si diffusion in KAlSi3O8 at high pressures: the effect of hydrogen. Journal of Geology: 96: 109-124.
London, D., Cerny, P., Loomis, J., Pan, J.J. (1990) Phosphorus in alkali feldspars of rare-element granitic pegmatites. The Canadian Mineralogist: 28: 771-786.
Waldron, K.A., Parsons, I., Brown, W.L. (1993) Solution-redeposition and the orthoclase-microcline transformation: evidence from granulites and relevance to 18O exchange. Mineralogical Magazine: 57: 687-695.
Allan, D.R. Angel, R.J. (1997) A high-pressure structural study of microcline (KAlSi3O8) to 7 GPa. European Journal of Mineralogy: 9: 263-275.

Internet Links for MicroclineHide

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.

Locality ListShow