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Microcline

This page kindly sponsored by Norman King
Formula:
K(AlSi3O8)
System:
Triclinic
Colour:
White, grey, greyish ...
Lustre:
Vitreous
Hardness:
6 - 6½
Member of:
Name:
Named 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.

Classification of Microcline

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
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http://www.mindat.org/min-2704.html
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Type Occurrence of Microcline

Occurrences of Microcline

Geological Setting:
Plutonic felsic rocks, pegmatites, high grade metamorphic veins, hydrothermal veins

Physical Properties of Microcline

Vitreous
Diaphaneity (Transparency):
Transparent, Translucent
Comment:
Pearly on cleavage
Colour:
White, grey, greyish yellow, yellowish, tan, salmon-pink, bluish green, green.
Streak:
White
Hardness (Mohs):
6 - 6½
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)

Crystallography of Microcline

Crystal System:
Triclinic
Class (H-M):
1 - Pinacoidal
Cell Parameters:
a = 8.5784Å, b = 12.96Å, c = 7.2112Å
α = 90.3°, β = 116.05°, γ = 89°
Ratio:
a:b:c = 0.662 : 1 : 0.556
Unit Cell Volume:
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 Microcline

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

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Edge Lines | Miller Indicies | Axes

Transparency
Opaque | Translucent | Transparent

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X-Ray Powder Diffraction:
Image Loading

Radiation - Copper Kα
Data Set:
Data courtesy of RRUFF project at University of Arizona, used with permission.

Optical Data of Microcline

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 Microcline

Formula:
K(AlSi3O8)
All elements listed in formula:
Common Impurities:
Fe,Ca,Na,Li,Cs,Rb,H2O,Pb

Relationship of Microcline to other Species

Member of:
Other Members of Group:
AlbiteNa(AlSi3O8)
Amazonite
Andesine(Na,Ca)[Al(Si,Al)Si2O8]
AnorthiteCa(Al2Si2O8)
Anorthoclase(Na,K)AlSi3O8
BanalsiteNa2BaAl4Si4O16
Buddingtonite(NH4)(AlSi3)O8
Bytownite(Ca,Na)[Al(Al,Si)Si2O8]
CelsianBa(Al2Si2O8)
DmisteinbergiteCa(Al2Si2O8)
FilatoviteK(Al,Zn)2(As,Si)2O8
HexacelsianBaAl2Si2O8
Hyalophane(K,Ba)[Al(Si,Al)Si2O8]
KokchetaviteK(AlSi3O8)
KumdykoliteNa(AlSi3O8)
Labradorite(Ca,Na)[Al(Al,Si)Si2O8]
Oligoclase(Na,Ca)[Al(Si,Al)Si2O8]
OrthoclaseK(AlSi3O8)
ParacelsianBa(Al2Si2O8)
ReedmergneriteNaBSi3O8
RubiclineRb(AlSi3O8)
SanidineK(AlSi3O8)
SlawsoniteSr(Al2Si2O8)
StronalsiteNa2SrAl4Si4O16
SvyatoslaviteCa(Al2Si2O8)
9.FA.05KaliophiliteKAlSiO4
9.FA.05KalsiliteKAlSiO4
9.FA.05Nepheline(Na,K)AlSiO4
9.FA.05Panunzite(K,Na)AlSiO4
9.FA.05Trikalsilite(K,Na)AlSiO4
9.FA.05Yoshiokaite(Ca,Na)[Al(Al,Si)O4]
9.FA.05MegakalsiliteKAlSiO4
9.FA.10MalinkoiteNaBSiO4
9.FA.15VirgiliteLiAlSi2O6
9.FA.25LisitsyniteKBSi2O6
9.FA.30AdulariaKAlSi3O8
9.FA.30Anorthoclase(Na,K)AlSi3O8
9.FA.30Buddingtonite(NH4)(AlSi3)O8
9.FA.30CelsianBa(Al2Si2O8)
9.FA.30Hyalophane(K,Ba)[Al(Si,Al)Si2O8]
9.FA.30OrthoclaseK(AlSi3O8)
9.FA.30SanidineK(AlSi3O8)
9.FA.30RubiclineRb(AlSi3O8)
9.FA.30MonalbiteNaAlSi3O8
9.FA.35AlbiteNa(AlSi3O8)
9.FA.35Andesine(Na,Ca)[Al(Si,Al)Si2O8]
9.FA.35AnorthiteCa(Al2Si2O8)
9.FA.35Bytownite(Ca,Na)[Al(Al,Si)Si2O8]
9.FA.35Labradorite(Ca,Na)[Al(Al,Si)Si2O8]
9.FA.35Oligoclase(Na,Ca)[Al(Si,Al)Si2O8]
9.FA.35ReedmergneriteNaBSi3O8
9.FA.40ParacelsianBa(Al2Si2O8)
9.FA.45SvyatoslaviteCa(Al2Si2O8)
9.FA.45KumdykoliteNa(AlSi3O8)
9.FA.50SlawsoniteSr(Al2Si2O8)
9.FA.55LisetiteCaNa2Al4Si4O16
9.FA.60BanalsiteNa2BaAl4Si4O16
9.FA.60StronalsiteNa2SrAl4Si4O16
9.FA.65DanburiteCaB2Si2O8
9.FA.65MaleeviteBaB2Si2O8
9.FA.65PekoviteSrB2Si2O8
9.FA.70Lingunite(Na,Ca)AlSi3O8
9.FA.75KokchetaviteK(AlSi3O8)
16.3.1LithositeK6Al4Si8O25 · 2H2O
16.3.2KaliophiliteKAlSiO4
16.3.3KalsiliteKAlSiO4
16.3.4LeuciteK(AlSi2O6)
16.3.6OrthoclaseK(AlSi3O8)
16.3.7SanidineK(AlSi3O8)
16.3.8MuscoviteKAl2(AlSi3O10)(OH)2

Other Names for Microcline

Name in Other Languages:
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

Other Information

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

References for Microcline

Reference List:
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 Microcline

Specimens:
The following Microcline specimens are currently listed for sale on minfind.com.

Localities for Microcline

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.
Mineral and/or Locality  
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