Difference between revisions of "Microcline"

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[[File:20.268-SC39857.jpg|thumb|'''MFA Acc. #:''' 20.268]]
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[[File:20.268-SC39857.jpg|thumb|Microcline pendant<br>MFA Acc. #: 20.268]]
 
== Description ==
 
== Description ==
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[[File:Feldsparemr1.jpg|thumb|Microcline (potassium feldspar)]]
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A variety of potash
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[[feldspar|feldspar]] that is chemically identical to
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[[orthoclase|orthoclase]]. However microcline has a triclinic crystalline system while orthoclase has a monoclinic crystalline system. Microcline may be clear, white, pale-yellow, brick-red, or green. Under a polarizing microscope, microcline displays a minute multiple twinning that forms a grating-like pattern. Amazon stone, or
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[[amazonite|amazonite]], is a green microcline that has been used since antiquity for decorative items. Microcline is used in making glass, porcelain, and enamel. Major deposits are found in Italy (Baveno), Norway (Kragerø), Madagascar, Russia (the Urals), and the U.S. (Colorado).
  
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A variety of potash [http://cameo.mfa.org/materials/fullrecord.asp?name=feldspar feldspar] that is chemically identical to [http://cameo.mfa.org/materials/fullrecord.asp?name=orthoclase orthoclase]. However microcline has a triclinic crystalline system while orthoclase has a monoclinic crystalline system. Under a polarizing microscope, microcline displays a minute multiple twinning that forms a grating-like pattern. Amazon stone, or [http://cameo.mfa.org/materials/fullrecord.asp?name=amazonite amazonite], is a green microcline that has been used since antiquity for decorative items. Microcline is used in making glass, porcelain, and enamel. Major deposits are found in Italy (Baveno), Norway (Kragerø), Madagascar, Russia (the Urals), and the U.S. (Colorado).
 
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[[File:Feldsparemr1.jpg|thumb|Microcline (potassium feldspar)]]
 
 
== Synonyms and Related Terms ==
 
== Synonyms and Related Terms ==
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[[File:Microcline.jpg|thumb|albite twinning under polarized light; credit Eurico Zimbres]]
 
amazonite; feldspar; microclina (Esp., Port.); microklien (Ned.)
 
amazonite; feldspar; microclina (Esp., Port.); microklien (Ned.)
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[[[SliderGallery rightalign|Microcline, PMA.TIF~FTIR (PMA)|Microcline IR-ATR RRUFF R050150.png~IR-ATR (RRUFF)|Microcline Raman RRUFF R050150.png~Raman (RRUFF)|microclineRS.jpg~Raman (RASMIN)]]]
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== Physical and Chemical Properties ==
  
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[[[SliderGallery rightalign|microclineRS.jpg~Raman]]]
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* Color= colorless, white, pale-yellow, brick-red, or green  
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* Crystal system = triclinic, exhibits albite twinning (grating pattern)
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== Other Properties ==
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* Cleavage = perfect in one direction and good in another
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* Fracture = uneven
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Color= colorless  Crystal system = triclinic, may exhibit albite twinning Cleavage is perfect in one direction and good in another
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* Luster = vitreous
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* Streak = white 
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* Fluorescence = generally inert; may show weak yellowish green in LW
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* Pleochroism = absent
  
 
{| class="wikitable"
 
{| class="wikitable"
Line 19: Line 26:
 
! scope="row"| Composition
 
! scope="row"| Composition
 
| K2O-Al2O3-6SiO2
 
| K2O-Al2O3-6SiO2
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|-
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! scope="row"| Mohs Hardness
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| 6.0-6.5
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|-
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! scope="row"| Density
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| 2.5-2.6 g/ml
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|-
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! scope="row"| Refractive index
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| 1.514- 1.539
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|-
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! scope="row"| Birefringence
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| undetectable to 0.007
 
|}
 
|}
  
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== Additional Images ==
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== Resources and Citations ==
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* Gem Identification Lab Manual, Gemological Institute of America, 2016.
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<gallery>
 
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File:pm30211microcline.jpg|Microcline (green)
 
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</gallery>
 
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== Sources Checked for Data in Record ==
 
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* G.S.Brady, ''Materials Handbook'', McGraw-Hill Book Co., New York, 1971  Comment: p. 316
 
* G.S.Brady, ''Materials Handbook'', McGraw-Hill Book Co., New York, 1971  Comment: p. 316
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* Jack Odgen, ''Jewellery of the Ancient World'', Rizzoli International Publications Inc., New York City, 1982
 
* Jack Odgen, ''Jewellery of the Ancient World'', Rizzoli International Publications Inc., New York City, 1982
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* ''Encyclopedia Britannica'', http://www.britannica.com  Comment: "microcline" [Accessed March 4, 2002]
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* ''Encyclopedia Britannica'', http://www.britannica.com  Comment: "microcline" Encyclopædia Britannica [Accessed March 4, 2002]
 
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* ''Ancient Egyptian Materials and Technologies'', Paul Nicholson, Ian Shaw (eds.), Cambridge University Press, Cambridge, 2000  Comment: B.Aston, J.Harrell, I.Shaw, "Stone" p. 21-22.
 
* ''Ancient Egyptian Materials and Technologies'', Paul Nicholson, Ian Shaw (eds.), Cambridge University Press, Cambridge, 2000  Comment: B.Aston, J.Harrell, I.Shaw, "Stone" p. 21-22.
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* Wikipedia: [https://en.wikipedia.org/wiki/Microcline Microcline] (Accessed Sept. 10, 2005 and Dec 2022)
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* Wikipedia, the free encyclopedia, at http://www.wikipedia.com  Comment: http://en.wikipedia.org/wiki/Microcline (Accessed Sept. 10, 2005)
 
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* ''Van Nostrand's Scientific Encyclopedia'', Douglas M. Considine (ed.), Van Nostrand Reinhold, New York, 1976
 
* ''Van Nostrand's Scientific Encyclopedia'', Douglas M. Considine (ed.), Van Nostrand Reinhold, New York, 1976
  

Latest revision as of 12:21, 19 December 2022

Microcline pendant
MFA Acc. #: 20.268

Description

Microcline (potassium feldspar)

A variety of potash Feldspar that is chemically identical to Orthoclase. However microcline has a triclinic crystalline system while orthoclase has a monoclinic crystalline system. Microcline may be clear, white, pale-yellow, brick-red, or green. Under a polarizing microscope, microcline displays a minute multiple twinning that forms a grating-like pattern. Amazon stone, or Amazonite, is a green microcline that has been used since antiquity for decorative items. Microcline is used in making glass, porcelain, and enamel. Major deposits are found in Italy (Baveno), Norway (Kragerø), Madagascar, Russia (the Urals), and the U.S. (Colorado).

Synonyms and Related Terms

albite twinning under polarized light; credit Eurico Zimbres

amazonite; feldspar; microclina (Esp., Port.); microklien (Ned.)

FTIR (PMA)

Microcline, PMA.TIF

IR-ATR (RRUFF)

Microcline IR-ATR RRUFF R050150.png

Raman (RRUFF)

Microcline Raman RRUFF R050150.png

Raman (RASMIN)

MicroclineRS.jpg

Physical and Chemical Properties

  • Color= colorless, white, pale-yellow, brick-red, or green
  • Crystal system = triclinic, exhibits albite twinning (grating pattern)
  • Cleavage = perfect in one direction and good in another
  • Fracture = uneven
  • Luster = vitreous
  • Streak = white
  • Fluorescence = generally inert; may show weak yellowish green in LW
  • Pleochroism = absent
Composition K2O-Al2O3-6SiO2
Mohs Hardness 6.0-6.5
Density 2.5-2.6 g/ml
Refractive index 1.514- 1.539
Birefringence undetectable to 0.007

Resources and Citations

  • Gem Identification Lab Manual, Gemological Institute of America, 2016.
  • G.S.Brady, Materials Handbook, McGraw-Hill Book Co., New York, 1971 Comment: p. 316
  • Jack Odgen, Jewellery of the Ancient World, Rizzoli International Publications Inc., New York City, 1982
  • Encyclopedia Britannica, http://www.britannica.com Comment: "microcline" [Accessed March 4, 2002]
  • Ancient Egyptian Materials and Technologies, Paul Nicholson, Ian Shaw (eds.), Cambridge University Press, Cambridge, 2000 Comment: B.Aston, J.Harrell, I.Shaw, "Stone" p. 21-22.
  • Wikipedia: Microcline (Accessed Sept. 10, 2005 and Dec 2022)
  • Van Nostrand's Scientific Encyclopedia, Douglas M. Considine (ed.), Van Nostrand Reinhold, New York, 1976

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