Sunstone (Aventurine feldspar)

Big Photo

Sunstone Dreamscape Cut
5.66 carats
© johndyergems.com

Sunstone is a plagioclase feldspar that has red, more rarely green or blue glitter which is caused by light reflections from tiny hematite or goethite platelets.

The name derives from sunstones believed to have been used for navigation in the Middle Ages.

Sunstone is the official gemstone of Oregon, USA.

Sunstone Gemstones by Colour

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

Sunstone Gemstones by Size

This table shows distribution of Sunstone 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:0.07 cts
Heaviest:30.75 cts
Average:5.83 cts
Total photos:94
Do you have a larger Sunstone? Why not upload a photo?
0.07ct to 3.14ct3.14ct to 6.21ct6.21ct to 9.27ct9.27ct to 12.34ct12.34ct to 15.41ct15.41ct to 18.48ct18.48ct to 21.55ct21.55ct to 24.61ct24.61ct to 27.68ct27.68ct to 30.75ct
General Information
A variety or type of:Feldspar
Chemical Formula
(Ca,Na)(Al,Si)
 
2
Si
 
2
O
 
8
Walter Schumann, Gemstones of the world (2001)
Photos of natural/un-cut material from mindat.org
Physical Properties of Sunstone
Mohs Hardness6 to 6.5
Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010)
Specific Gravity2.62 to 2.67
Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010)
More from other references
TenacityBrittle
Walter Schumann, Gemstones of the world (2001)
Cleavage QualityPerfect
Ulrich Henn and Claudio C. Milisenda, Gemmological Tables (2004)
FractureSplintery
Walter Schumann, Gemstones of the world (2001)
Optical Properties of Sunstone
Refractive Index1.525 to 1.552
Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010)
More from other references
Optical CharacterBiaxial/-
Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010)
Birefringence0.007 to 0.010
Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010)
More from other references
PleochroismWeak or absent
Walter Schumann, Gemstones of the world (2001)
DispersionNone
Walter Schumann, Gemstones of the world (2001)
Colour
Colour (General)Reddish-brown, brownish-red, golden brown. Aventurescent
Ulrich Henn and Claudio C. Milisenda, Gemmological Tables (2004)
TransparencyTranslucent,Opaque
Ulrich Henn and Claudio C. Milisenda, Gemmological Tables (2004)
Fluorescence & other light emissions
Fluorescence (General)Dark brown-red
Walter Schumann, Gemstones of the world (2001)
Crystallography of Sunstone
Crystal SystemTriclinic
Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010)
HabitRare, solid aggregates
Walter Schumann, Gemstones of the world (2001)
Further Information
Mineral information:Sunstone information at mindat.org
Significant Gem Localities
Australia
 
  • Northern Territory
    • Central Desert Region
      • Harts Range (Harts Ranges; Hartz Range; Hartz Ranges)
        • Mt Riddock Station
Brown and Bracewell (1984)
USA
 
  • Oregon
    • Harney Co.
Johnston et al. (1991)
    • Lake Co.
      • Plush
Henn and Bank (1992)
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