Moldavite

Big Photo

Czech Republic
9.63 carats
© irocks.com

Moldavite is named after the the former german name of the river Moldau, Czech Republic, where the material was first found in 1787. Czechs call them "vltavin", after the Czech name for the same river, the Vltava.

Moldavite is a natural glass, a variety of Tektite. Tektites are formed when terrestrial rock and soil is melted and ejected into space by meteorite impacts, and each impact produces a limited strewn field which is named. Consequently the name "moldavite" can only be used for tektites from one specific impact (in this case the Ries crater in Germany), the strewn field being mainly in the Czech Republic, together with minor neighboring areas of Germany and Austria. It is nonsense for other glasses to be marketed using variations of the name like "African Moldavite" (sic).

Moldavites are the most transparent of all the various types of tektites. They are found in many different color shades between brown and green, but normally only the ones with bottle-green hue are used for faceting. Occasionally faceted green bottle glass gets fraudulently passed off as "moldavite". True moldavite gems can be identified by their vermiform inclusions of lechatelierite (pure silica glass - melted quartz).

Moldavite Gemstones by Colour

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

Moldavite Gemstones by Size

This table shows distribution of Moldavite 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:2.68 cts
Heaviest:14.01 cts
Average:8.97 cts
Total photos:8
Do you have a larger Moldavite? Why not upload a photo?
2.68ct to 3.81ct3.81ct to 4.95ct4.95ct to 6.08ct6.08ct to 7.21ct7.21ct to 8.35ct8.35ct to 9.48ct9.48ct to 10.61ct10.61ct to 11.74ct11.74ct to 12.88ct12.88ct to 14.01ct
General Information
A variety or type of:Tektite
Chemical Formula
SiO
 
2
(+Al
 
2
O
 
3
)
Walter Schumann, Gemstones of the world (2001)
Photos of natural/un-cut material from mindat.org
Physical Properties of Moldavite
Mohs Hardness5.5
Walter Schumann, Gemstones of the world (2001)
More from other references
Specific Gravity2.32 to 2.38
Walter Schumann, Gemstones of the world (2001)
More from other references
Cleavage QualityNone
Walter Schumann, Gemstones of the world (2001)
FractureConchoidal
Walter Schumann, Gemstones of the world (2001)
Optical Properties of Moldavite
Refractive Index1.48 to 1.54
Walter Schumann, Gemstones of the world (2001)
More from other references
Optical CharacterIsotropic
Ulrich Henn and Claudio C. Milisenda, Gemmological Tables (2004)
BirefringenceNone
Walter Schumann, Gemstones of the world (2001)
PleochroismAbsent
Walter Schumann, Gemstones of the world (2001)
DispersionNone
Walter Schumann, Gemstones of the world (2001)
Colour
Colour (General)Bottle-green to brown-green
Walter Schumann, Gemstones of the world (2001)
More from other references
Causes of ColourYellowish green, Fe2+ in octahedral coordination.
W. William Hanneman, Pragmatic Spectroscopy For Gemologists (2011)
TransparencyTransparent,Translucent,Opaque
Walter Schumann, Gemstones of the world (2001)
More from other references
LustreVitreous
Walter Schumann, Gemstones of the world (2001)
Fluorescence & other light emissions
Fluorescence (General)None
Walter Schumann, Gemstones of the world (2001)
Fluorescence (X-RAY)A faint yellowish green.
Michael O’Donoghue, Gems, Sixth edition (2006)
Crystallography of Moldavite
Crystal SystemAmorphous
Walter Schumann, Gemstones of the world (2001)
More from other references
Geological Environment
Where found:Space or impact (large meteorites)
E. Ya. Kievlenko, Geology of gems (2003)
Inclusions in Moldavite
Gas bubbles, swirl marks - Gemmological Tables, Ulrich Henn and Claudio C. Milisenda, 2004, p 2
Further Information
Mineral information:Moldavite information at mindat.org
Significant Gem Localities
Czech Republic
 
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