Sanidine

Sanidine is a glassy variety of Orthoclase feldspar that occurs in the German Rhineland and in USA. Colourless, beige and attractive warm-brown stones are faceted.

Sanidine Gemstones by Colour

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

Sanidine Gemstones by Size

This table shows distribution of Sanidine 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:2.50 cts
Heaviest:40.13 cts
Average:12.34 cts
Total photos:14
Do you have a larger Sanidine? Why not upload a photo?
2.50ct to 6.26ct6.26ct to 10.03ct10.03ct to 13.79ct13.79ct to 17.55ct17.55ct to 21.32ct21.32ct to 25.08ct25.08ct to 28.84ct28.84ct to 32.60ct32.60ct to 36.37ct36.37ct to 40.13ct
General Information
A variety or type of:Orthoclase, which is a variety of Feldspar
Chemical Formula
KAlSi
 
3
O
 
8
Michael O’Donoghue, Gems, Sixth Edition (2006)
Photos of natural/un-cut material from mindat.org
Sanidine Treatments
Some sanidine subjected to iridation turns amber or smoky coloured.
Physical Properties of Sanidine
Mohs Hardness6
Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010)
More from other references
Specific Gravity2.54 to 2.61
Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010)
More from other references
TenacityBrittle
Michael O’Donoghue, Gems, Sixth Edition (2006)
Cleavage QualityGood
Michael O’Donoghue, Gems, Sixth Edition (2006) Excellent to good
FractureUneven,Conchoidal
Michael O’Donoghue, Gems, Sixth Edition (2006)
Optical Properties of Sanidine
Refractive Index1.518 to 1.536
Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010)
More from other references
Optical CharacterBiaxial/-
Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010)
More from other references
Birefringence0.005 to 0.008
Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010)
More from other references
PleochroismWeak
Michael O’Donoghue, Gems, Sixth Edition (2006)
DispersionWeak
Michael O’Donoghue, Gems, Sixth Edition (2006)
Colour
Colour (General)Light gray to light brownish variety
Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010)
More from other references
TransparencyTransparent,Translucent
Michael O’Donoghue, Gems, Sixth Edition (2006)
LustreVitreous
Michael O’Donoghue, Gems, Sixth Edition (2006)
Fluorescence & other light emissions
Fluorescence (General)Weak reddish orange under both LWUV and SWUV (Madagascar)
Michael O’Donoghue, Gems, Sixth Edition (2006)
Crystallography of Sanidine
Crystal SystemMonoclinic
Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010)
More from other references
HabitA flattened crystal
Michael O’Donoghue, Gems, Sixth Edition (2006)
Geological Environment
Where found:Sanidine is a common constituent in acid and intermediate volcanic rocks such as rhyolites, dacites and trachytes; where the rock cooled quickly at above approximately 900°C, sanidine is the stable structure
Michael O’Donoghue, Gems, Sixth Edition (2006)
Further Information
Mineral information:Sanidine information at mindat.org
Significant Gem Localities
Madagascar
 
  • Anosy
    • Betroka
      • Mahasoa Est
Myanmar
 
  • Mandalay Region
    • Pyin-Oo-Lwin District
      • Mogok Township
        • 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
Sri Lanka
 
  • Sabaragamuwa Province
    • Ratnapura District
      • Ratnapura
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