Hyalite

Hyalite (Greek - glass stone) is water-clear, glass-like and is generally considered the purest and clearest Opal variety. As a cut gem, it can be confused with glass.

Hyalite Gemstones by Colour

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

Hyalite Gemstones by Size

This table shows distribution of Hyalite 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:0.96 cts
Heaviest:18.18 cts
Average:8.54 cts
Total photos:5
Do you have a larger Hyalite? Why not upload a photo?
0.96ct to 2.68ct2.68ct to 4.40ct4.40ct to 6.13ct6.13ct to 7.85ct7.85ct to 9.57ct9.57ct to 11.29ct11.29ct to 13.01ct13.01ct to 14.74ct14.74ct to 16.46ct16.46ct to 18.18ct
General Information
A variety or type of:Common Opal, which is a variety of Opal
Chemical Formula
SiO
 
2
· nH
 
2
O
Walter Schumann, Gemstones of the world (2001)
Hyalite Simulants
As a cut gem, it can be confused with glass. - Opal, Lithographie, 2007
Physical Properties of Hyalite
Mohs Hardness5.5 to 6.5
Walter Schumann, Gemstones of the world (2001)
TenacityBrittle
Walter Schumann, Gemstones of the world (2001)
Cleavage QualityNone
Walter Schumann, Gemstones of the world (2001)
FractureConchoidal,Splintery
Walter Schumann, Gemstones of the world (2001)
Heat SensitivitySensitive, becomes soft and breaks up
Lithographie, Opal (2007)
Optical Properties of Hyalite
Refractive Index1.37 to 1.52
Walter Schumann, Gemstones of the world (2001)
BirefringenceNone
Walter Schumann, Gemstones of the world (2001)
Colour
Colour (General)Colourless with strong sheen
Walter Schumann, Gemstones of the world (2001)
TransparencyTransparent,Translucent
Walter Schumann, Gemstones of the world (2001)
Fluorescence & other light emissions
Fluorescence (General)Shows brilliant green fluorescence, especially under SW, due to uranium impurities.
Lithographie, Opal (2007)
Crystallography of Hyalite
Crystal SystemAmorphous
Walter Schumann, Gemstones of the world (2001)
HabitUsually takes globular, botryoidal forms
Lithographie, Opal (2007)
Further Information
Mineral information:Hyalite information at mindat.org
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