Andesine

Big Photo

China
2.05 carats
© Mineral Classics

Andesine feldspar is composed of 50-70% albite and 30-50% anorthite.

Andesine was first described in 1841 for an occurrence in the Marmato mine, Colombia. It is named after the Andes mountains of South America.

Andesine is found in a range of colours, from red, honey-red to orange, yellow, champagne and green.

Andesine Gemstones by Colour

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

Andesine Gemstones by Size

This table shows distribution of Andesine 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:0.41 cts
Heaviest:10.58 cts
Average:2.81 cts
Total photos:25
Do you have a larger Andesine? Why not upload a photo?
0.41ct to 1.43ct1.43ct to 2.44ct2.44ct to 3.46ct3.46ct to 4.48ct4.48ct to 5.50ct5.50ct to 6.51ct6.51ct to 7.53ct7.53ct to 8.55ct8.55ct to 9.56ct9.56ct to 10.58ct
General Information
A variety or type of:Feldspar
Chemical Formula
Na(70-50%)Ca(30-50%)(Al,Si)AlSi
 
2
O
 
8
Michael O’Donoghue, Gems, Sixth Edition (2006)
Photos of natural/un-cut material from mindat.org
Andesine Treatments
Red and green: immersion - green center with red outer section may suggest a potentially copper diffused stone - Blue Chart Gem Identification, Herve Nicolas Lazzarelli, 2010, p 9
Physical Properties of Andesine
Mohs Hardness6 to 6.5
Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010)
More from other references
Specific Gravity2.65 to 2.69
Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010)
More from other references
TenacityBrittle
Michael O’Donoghue, Gems, Sixth Edition (2006)
Cleavage QualityPerfect
Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010)
More from other references
FractureUneven,Conchoidal
Michael O’Donoghue, Gems, Sixth Edition (2006)
Optical Properties of Andesine
Refractive Index1.543 to 1.564
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
Birefringence0.007 to 0.011
Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010)
More from other references
DispersionWeak
Michael O’Donoghue, Gems, Sixth Edition (2006)
Colour
Colour (General)Light pink, also white, gray, yellowish, greenish.
Walter Schumann, Gemstones of the world (2001)
More from other references
TransparencyTransparent,Translucent,Opaque
Ulrich Henn and Claudio C. Milisenda, Gemmological Tables (2004)
More from other references
LustreVitreous,Dull (Earthy)
Michael O’Donoghue, Gems, Sixth Edition (2006) Vitreous to dull
Fluorescence & other light emissions
Fluorescence (Short Wave UV)Blue, pink, yellow, yellowish brown. Weak red emission with an even weaker blue surface related luminescence has been reported for red andesine from the Democratic Republic of Congo.
Michael O’Donoghue, Gems, Sixth Edition (2006)
Fluorescence (Long-Wave UV)Red andesine from the Democratic
Republic of Congo fluoresced a weak to medium orange.
Michael O’Donoghue, Gems, Sixth Edition (2006)
Crystallography of Andesine
Crystal SystemTriclinic
Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010)
More from other references
Geological Environment
Where found:Andesine is only a minor constituent in most granites and syenites but is the dominant feldspar in a wide range of igneous rocks of basic to intermediate and certain igneous rocks called appropriately andesites. It is also found in some metamorphic rocks as a minor constituent.
Michael O’Donoghue, Gems, Sixth Edition (2006)
Further Information
Mineral information:Andesine information at mindat.org
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