Black Opal

Black Opal is Precious Opal with dark gray, dark blue, dark green, and gray-black background colour and play-of-colour. Deep black is an exception.

Black opal is rarer than White opal.

Black Opal Gemstones by Colour

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

Black Opal Gemstones by Size

This table shows distribution of Black 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:1.34 cts
Heaviest:20.04 cts
Average:7.44 cts
Total photos:18
Do you have a larger Black Opal? Why not upload a photo?
1.34ct to 3.21ct3.21ct to 5.08ct5.08ct to 6.95ct6.95ct to 8.82ct8.82ct to 10.69ct10.69ct to 12.56ct12.56ct to 14.43ct14.43ct to 16.30ct16.30ct to 18.17ct18.17ct to 20.04ct
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)
Photos of natural/un-cut material from mindat.org
Synthetic Black Opal
Light-coloured opals can be darkened using several methods to simulate Black opals. - Opal, Lithographie, 2007
Physical Properties of Black Opal
Mohs Hardness6 to 6.5
Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010)
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 Black 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)Dark background colour
Gemdat.org, Management Team (2012)
TransparencyTransparent,Translucent,Opaque
Ulrich Henn and Claudio C. Milisenda, Gemmological Tables (2004)
LustreVitreous
Arthur Thomas, Gemstones (2009)
Crystallography of Black Opal
Crystal SystemAmorphous
Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010)
HabitMassive
Arthur Thomas, Gemstones (2009)
Further Information
Mineral information:Black Opal information at mindat.org
Significant Gem Localities
Australia
 
  • New South Wales
    • Finch Co.
Opal, Lithographie, 2007
  • South Australia
    • North West Province
      • Mintabie district
www.mineshaft.com.au/1.htm.
    • Stuart Shelf
      • Andamooka Ranges
Opal, Lithographie, 2007
USA
 
  • Nevada
    • Humboldt Co.
      • Virgin Valley
[www.johnbetts-fineminerals.com]
Copyright © Jolyon & Katya Ralph 1993-2017. Site Map. Locality, gem & photograph data are the copyright of the individuals who submitted them. For more information please contact the . Gemdat.org is an online information resource dedicated to providing free gemmological information to all.