Aventurine

Big Photo

Brazil
19.54 carats
© gemselect.com

The name aventurine derives from the Italian "a ventura" meaning "by chance".

Aventurine is a feebly translucent, fine-grained to compact variety of Quartzite, the surface of which has a speckled, metallic sheen, usually of a reddish-brown colour, but occasionally yellow, white, blue or green. This appearance is caused by the presence, in the colourless quartz substance, of numbers of enclosures (scales of mica, plates of chrome-mica fuchsite, etc.), which can always be seen with the aid of the microscope, and sometimes with a simple lens, or with the naked eye.

Also known as Indian Jade.

Aventurine Gemstones by Colour

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

Aventurine Gemstones by Size

This table shows distribution of Aventurine 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:1.23 cts
Heaviest:36.47 cts
Average:16.80 cts
Total photos:16
Do you have a larger Aventurine? Why not upload a photo?
1.23ct to 4.75ct4.75ct to 8.28ct8.28ct to 11.80ct11.80ct to 15.33ct15.33ct to 18.85ct18.85ct to 22.37ct22.37ct to 25.90ct25.90ct to 29.42ct29.42ct to 32.95ct32.95ct to 36.47ct
General Information
A variety or type of:
Other Names/Trade Names:
Chemical Formula
SiO
 
2
Walter Schumann, Gemstones of the world (2001)
Photos of natural/un-cut material from mindat.org
Synthetic Aventurine
Aventurine-glass is an artificial product which resembles natural aventurine but possesses an even finer appearance. It is a colourless glass in which are embedded numerous small red octahedra, the faces of which are equilateral triangles. The chemical composition of the material, the well-defined crystalline form, together with the red colour and strong metallic lustre of the enclosures, point to the fact that the latter consists of metallic copper. The much lower hardness of aventurine-glass, together with the form of the enclosures, which can be readily made out with a lens, definitely distinguishes it in all cases from natural aventurine and from sunstone. - Precious stones, Max Bauer, 1968, p 503
Physical Properties of Aventurine
Mohs Hardness7 to 6.5
Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010)
More from other references
Specific Gravity2.64 to 2.69
Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010)
More from other references
TenacityBrittle
Walter Schumann, Gemstones of the world (2001)
Cleavage QualityNone
Walter Schumann, Gemstones of the world (2001)
FractureConchoidal,Splintery
Max Bauer, Precious stones (1968)
Optical Properties of Aventurine
Refractive Index1.544 to 1.553
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)
PleochroismAbsent
Walter Schumann, Gemstones of the world (2001)
DispersionNone
Walter Schumann, Gemstones of the world (2001)
Colour
Colour (General)Green, red-brown, gold-brown
Walter Schumann, Gemstones of the world (2001)
More from other references
Colour (Chelsea Filter)Reddish
Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010)
Causes of ColourGreen, chromian mica (fuchsite) inclusions. Greenish yellow, color center.
W. William Hanneman, Pragmatic Spectroscopy For Gemologists (2011)
TransparencyTranslucent,Opaque
Walter Schumann, Gemstones of the world (2001)
More from other references
Fluorescence & other light emissions
Fluorescence (General)Green aventurine: reddish
Walter Schumann, Gemstones of the world (2001)
More from other references
Crystallography of Aventurine
Crystal SystemTriclinic
Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010)
HabitMassive
Walter Schumann, Gemstones of the world (2001)
Geological Environment
Where found:Occurs both in primary deposits and also as loose pebbles.
Max Bauer, Precious stones (1968)
Inclusions in Aventurine
Aventurescence caused by platy inclusions of green mica (fuchsite) - Blue Chart Gem Identification, Herve Nicolas Lazzarelli, 2010, p 7
Further Information
Mineral information:Aventurine information at mindat.org
Significant Gem Localities
Austria
 
  • Styria
Max Bauer, Precious stones (1968)
India
 
  • Karnataka
    • Bellary district
Max Bauer, Precious stones (1968)
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