Microcline

Big Photo

Amazonite
Brazil
2.93 carats
© gemselect.com

Microcline (Greek - small slope) has the same chemical composition as orthoclase but is classified in the triclinic crystal system.

The blue-green feldspar amazonite is the only gem variety of microcline.

Microcline Gemstones by Colour

This table shows the variety of hues this gemstone can be found in. Click on a photo for more information.
 
 
 
 

Microcline Gemstones by Size

This table shows distribution of Microcline gemstone sizes that are listed on this site. This can give a good indication as to the general availability of this gemstone in different sizes.
Contributed photos
Lightest:0.31 cts
Heaviest:33.86 cts
Average:10.59 cts
Total photos:28
Do you have a larger Microcline? Why not upload a photo?
0.31ct to 3.67ct3.67ct to 7.02ct7.02ct to 10.38ct10.38ct to 13.73ct13.73ct to 17.09ct17.09ct to 20.44ct20.44ct to 23.80ct23.80ct to 27.15ct27.15ct to 30.51ct30.51ct to 33.86ct
General Information
A variety or type of:Feldspar
Varieties/Types:
Amazonite - A green to blue-green variety of Microcline.
Chemical Formula
KAlSi
 
3
O
 
8
Arthur Thomas, Gemstones (2009)
Photos of natural/un-cut material from mindat.org
Physical Properties of Microcline
Mohs Hardness6 to 6.5
Michael O’Donoghue, Gems, Sixth Edition (2006)
More from other references
Specific Gravity2.55 to 2.63
Michael O’Donoghue, Gems, Sixth Edition (2006)
More from other references
Cleavage QualityPerfect
Michael O’Donoghue, Gems, Sixth Edition (2006)
FractureUneven,Conchoidal
Michael O’Donoghue, Gems, Sixth Edition (2006)
More from other references
Optical Properties of Microcline
Refractive Index1.514 to 1.539
Michael O’Donoghue, Gems, Sixth Edition (2006) Alpha 1.514–1.529; beta 1.518–1.533; gamma 1.521–1.539More from other references
Optical CharacterBiaxial/-
Michael O’Donoghue, Gems, Sixth Edition (2006)
More from other references
Birefringence0.008 to 0.010
Michael O’Donoghue, Gems, Sixth Edition (2006)
More from other references
PleochroismWeak
Michael O’Donoghue, Gems, Sixth Edition (2006)
More from other references
DispersionWeak
Michael O’Donoghue, Gems, Sixth Edition (2006)
More from other references
Colour
Colour (General)Commonly white to pale yellow or salmon, also may be blue to green
Michael O’Donoghue, Gems, Sixth Edition (2006)
More from other references
Causes of ColourBlue (amazonite), color center involving Pb3+ and structural water
W. William Hanneman, Pragmatic Spectroscopy For Gemologists (2011)
TransparencyTranslucent,Opaque
Michael O’Donoghue, Gems, Sixth Edition (2006) Rarely transparentMore from other references
LustreVitreous
Michael O’Donoghue, Gems, Sixth Edition (2006)
More from other references
Fluorescence & other light emissions
Fluorescence (Short Wave UV)May fluoresce with a weak red or moderate blue colour, bluish white or pale greyish green. Microcline from Franklin, New Jersey, is reported as having a medium blue–grey fluorescence.
Michael O’Donoghue, Gems, Sixth Edition (2006)
Crystallography of Microcline
Crystal SystemTriclinic
Michael O’Donoghue, Gems, Sixth Edition (2006)
More from other references
HabitPrismatic
Arthur Thomas, Gemstones (2009)
Geological Environment
Where found:Microcline commonly occurs in plutonic igneous rocks such as granites and syenites that cooled slowly and at considerable depth.
Michael O’Donoghue, Gems, Sixth Edition (2006)
Further Information
Mineral information:Microcline information at mindat.org
Significant Gem Localities
Madagascar
 
  • Betsiboka
    • Tsaratanàna
      • Ambakireny
[var: Amazonite] Madagascar, extraLapis English No.1, 2001, p. 43
Myanmar
 
  • Mandalay Region
    • Pyin-Oo-Lwin District
      • Mogok Township
        • Kyatpyin North
[var: Amazonite] Ted Themelis (2008) Gems & mines of Mogok
        • Kyauk-Pyat-That
Ted Themelis (2008) Gems & mines of Mogok
        • Mogok Valley
Ted Themelis (2008) Gems & mines of Mogok
Ted Themelis (2008) Gems & mines of Mogok
        • Pein-Pyit (Painpyit; Pyan Pyit)
Ted Themelis (2008) Gems & mines of Mogok
Peru
 
  • Huancavelica
    • Huancavelica Province
[var: Amazonite]
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