Moonstone

Big Photo

Myanmar
4.57 carats
© Palagems

Moonstone is colourless, very translucent, or almost perfectly transparent feldspar, which in certain direction reflects a bluish, milky light, that has been compared to the light of the moon.

Moonstone is a potassium feldspar of the orthoclase species with white shimmer, similar to moonshine (therefore the name), called adularescence. Thin alternating layers of orthoclase and albite create the light interference in this material that is responsible for its "shiller" or "floating moon effect".

Only specimens which show this sheen in a typical manner are cut as gems. To display the beauty of this stone to the best possible advantage , it is cut with a convex, polished surface of moderately strong curvature about the face which exhibits the sheen. The stone is very effective in cut and polished spheres, which may be strung together and worn as beads or for other ornamental purposes, when they have a certain resemblance to white pearls. Moonstone is always cut either en cabochon or with a plane surface, never with facets.

Moonstone Gemstones by Colour

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

Moonstone Gemstones by Size

This table shows distribution of Moonstone 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:1.39 cts
Heaviest:37.22 cts
Average:12.32 cts
Total photos:54
Do you have a larger Moonstone? Why not upload a photo?
1.39ct to 4.97ct4.97ct to 8.56ct8.56ct to 12.14ct12.14ct to 15.72ct15.72ct to 19.31ct19.31ct to 22.89ct22.89ct to 26.47ct26.47ct to 30.05ct30.05ct to 33.64ct33.64ct to 37.22ct
General Information
A variety or type of:Orthoclase, which is a variety of Feldspar
Other Names/Trade Names:
Chemical Formula
KAlSi
 
3
O
 
8
Walter Schumann, Gemstones of the world (2001)
Photos of natural/un-cut material from mindat.org
Moonstone Simulants
Imitated by adularescent synthetic spinel (possibly with mirror-like back coating), milky chalcedony, glass - Blue Chart Gem Identification, Herve Nicolas Lazzarelli, 2010, p 8
Physical Properties of Moonstone
Mohs Hardness6 to 6.5
Ulrich Henn and Claudio C. Milisenda, Gemmological Tables (2004)
Specific Gravity2.56 to 2.60
Ulrich Henn and Claudio C. Milisenda, Gemmological Tables (2004)
More from other references
Cleavage QualityPerfect
Ulrich Henn and Claudio C. Milisenda, Gemmological Tables (2004)
FractureUneven,Conchoidal
Walter Schumann, Gemstones of the world (2001)
Optical Properties of Moonstone
Refractive Index1.518 to 1.527
Ulrich Henn and Claudio C. Milisenda, Gemmological Tables (2004)
More from other references
Optical CharacterBiaxial/-
Ulrich Henn and Claudio C. Milisenda, Gemmological Tables (2004)
Birefringence0.006 to 0.007
Ulrich Henn and Claudio C. Milisenda, Gemmological Tables (2004)
PleochroismAbsent
Walter Schumann, Gemstones of the world (2001)
DispersionNone
Walter Schumann, Gemstones of the world (2001)
Colour
Colour (General)Colourless, white, adularescent with a silvery or bluish sheen, green, brownish, reddish.
Ulrich Henn and Claudio C. Milisenda, Gemmological Tables (2004)
More from other references
TransparencyTransparent,Translucent
Ulrich Henn and Claudio C. Milisenda, Gemmological Tables (2004)
More from other references
LustreVitreous
Walter Schumann, Gemstones of the world (2001)
Fluorescence & other light emissions
Fluorescence (General)Weak; bluish, orange
Walter Schumann, Gemstones of the world (2001)
Fluorescence (Short Wave UV)Inert to orangy-(reddish)
Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010)
More from other references
Fluorescence (Long-Wave UV)Inert to blue (and pinkish)
Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010)
Crystallography of Moonstone
Crystal SystemMonoclinic
Ulrich Henn and Claudio C. Milisenda, Gemmological Tables (2004)
HabitPrismatic
Walter Schumann, Gemstones of the world (2001)
Geological Environment
Where found:The most prominent source is in the gravels and pegmatites
Michael O’Donoghue, Gems, Sixth Edition (2006)
Inclusions in Moonstone
Typical "centipede" inclusions - Blue Chart Gem Identification, Herve Nicolas Lazzarelli, 2010, p 8

Healing cracks, crystal inclusions, cleavage cracks - Gemmological Tables, Ulrich Henn and Claudio C. Milisenda, 2004, p 5
Further Information
Mineral information:Moonstone information at mindat.org
Significant Gem Localities
Myanmar
 
  • Mandalay Region (Mandalay Division)
    • Pyin-Oo-Lwin District
      • Mogok Township
        • Bernardmyo
Ted Themelis (2008) Gems & mines of Mogok
Ted Themelis (2008) Gems & mines of Mogok
        • Chaung-gyi
Ted Themelis (2008) Gems & mines of Mogok
Ted Themelis (2008) Gems & mines of Mogok
Ted Themelis (2008) Gems & mines of Mogok
        • Kin (Guard Post)
Ted Themelis (2008) Gems & mines of Mogok
        • Kyatpyin North
Ted Themelis (2008) Gems & mines of Mogok
        • Kyauk-Pyat-That
Ted Themelis (2008) Gems & mines of Mogok
Ted Themelis (2008) Gems & mines of Mogok
        • Marble Ark
Ted Themelis (2008) Gems & mines of Mogok
Ted Themelis (2008) Gems & mines of Mogok
        • Mogok Valley
          • Dattaw-taung (Dattaw hill)
Ted Themelis (2008) Gems & mines of Mogok
Ted Themelis (2008) Gems & mines of Mogok
Ted Themelis (2008) Gems & mines of Mogok
Ted Themelis (2008) Gems & mines of Mogok
Ted Themelis (2008) Gems & mines of Mogok
Ted Themelis (2008) Gems & mines of Mogok
Ted Themelis (2008) Gems & mines of Mogok
Ted Themelis (2008) Gems & mines of Mogok
Ted Themelis (2008) Gems & mines of Mogok
Ted Themelis (2008) Gems & mines of Mogok
Ted Themelis (2008) Gems & mines of Mogok
Ted Themelis (2008) Gems & mines of Mogok
Ted Themelis (2008) Gems & mines of Mogok
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
Ted Themelis (2008) Gems & mines of Mogok
Ted Themelis (2008) Gems & mines of Mogok
Sri Lanka
 
  • Sabaragamuwa Province
    • Ratnapura District
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