Crystal Opal

Big Photo

Australia
24.92 carats
© irocks.com

Transparent or semi-transparent with strong play-of-colour on colourless, vitreous surface. Crystal opal is sometimes equated with Jelly opal (Water Opal) because of its clarity.

Crystal Opal Gemstones by Colour

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

Crystal Opal Gemstones by Size

This table shows distribution of Crystal Opal 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:1.14 cts
Heaviest:24.92 cts
Average:7.25 cts
Total photos:6
Do you have a larger Crystal Opal? Why not upload a photo?
1.14ct to 3.52ct3.52ct to 5.90ct5.90ct to 8.27ct8.27ct to 10.65ct10.65ct to 13.03ct13.03ct to 15.41ct15.41ct to 17.79ct17.79ct to 20.16ct20.16ct to 22.54ct22.54ct to 24.92ct
General Information
A variety or type of:Precious Opal, which is a variety of Opal
Chemical Formula
SiO
 
2
+ H
 
2
O
Ulrich Henn and Claudio C. Milisenda, Gemmological Tables (2004)
Physical Properties of Crystal Opal
Mohs Hardness5.5 to 6.5
Ulrich Henn and Claudio C. Milisenda, Gemmological Tables (2004)
Specific Gravity1.97 to 2.22
Ulrich Henn and Claudio C. Milisenda, Gemmological Tables (2004)
TenacityBrittle
Walter Schumann, Gemstones of the world (2001)
Cleavage QualityNone
Walter Schumann, Gemstones of the world (2001)
FractureConchoidal
Arthur Thomas, Gemstones (2009)
Optical Properties of Crystal Opal
Refractive Index1.370 to 1..470
Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010)
Optical CharacterIsotropic
Arthur Thomas, Gemstones (2009)
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)Black, white, colourless, yellow, bluish
Gemdat.org, Management Team (2012) The colour play is visible both on the surface and in the interior
TransparencyTransparent,Translucent
Gemdat.org, Management Team (2012)
LustreVitreous
Arthur Thomas, Gemstones (2009)
Crystallography of Crystal Opal
Crystal SystemAmorphous
Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010)
HabitMassive
Arthur Thomas, Gemstones (2009)
Further Information
Mineral information:Crystal Opal information at mindat.org
Significant Gem Localities
Australia
 
  • Queensland
    • Paroo Shire
  • South Australia
    • Central North
    • North West Province
      • Mintabie district
USA
 
  • Nevada
    • Humboldt Co.
      • Virgin Valley
  • Oregon
    • Morrow Co.
Holzhey (1997)
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