Fire Opal

Big Photo

Mexico
5.83 carats
© Mineral Classics

Fire opal (named after its orange colour) has red, orange, yellow body colour. It doesn't always show play-of-colour and is usually milky and turbid. The best qualities are clear and transparent, it makes them suitable for being faceted. They are very sensitive to every stress.

Fire Opal Gemstones by Colour

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

Fire Opal Gemstones by Size

This table shows distribution of Fire 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:0.10 cts
Heaviest:76.1 cts
Average:5.75 cts
Total photos:108
Do you have a larger Fire Opal? Why not upload a photo?
0.10ct to 7.70ct7.70ct to 15.30ct15.30ct to 22.90ct22.90ct to 30.50ct30.50ct to 38.10ct38.10ct to 45.70ct45.70ct to 53.30ct53.30ct to 60.90ct60.90ct to 68.50ct68.50ct to 76.10ct
General Information
A variety or type of:Opal
Chemical Formula
SiO
 
2
· nH
 
2
O
Walter Schumann, Gemstones of the world (2001)
More from other references
Photos of natural/un-cut material from mindat.org
Physical Properties of Fire Opal
Mohs Hardness6 to 6.5
gemdat.org, Editorial Team (2012)
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,Splintery
Walter Schumann, Gemstones of the world (2001)
Optical Properties of Fire 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)Red, orange, yellow
Walter Schumann, Gemstones of the world (2001)
More from other references
Causes of ColourOrange to red, microscopic to sub-microscopic inclusions of iron hydrous oxides.
W. William Hanneman, Pragmatic Spectroscopy For Gemologists (2011)
TransparencyTransparent,Translucent,Opaque
Ulrich Henn and Claudio C. Milisenda, Gemmological Tables (2004)
LustreVitreous
Arthur Thomas, Gemstones (2009)
Fluorescence & other light emissions
Fluorescence (General)Greenish to brown
Walter Schumann, Gemstones of the world (2001)
Crystallography of Fire Opal
Crystal SystemAmorphous
Walter Schumann, Gemstones of the world (2001)
More from other references
HabitMassive
Arthur Thomas, Gemstones (2009)
Further Information
Mineral information:Fire Opal information at mindat.org
Significant Gem Localities
Australia
 
  • New South Wales
    • Finch Co.
  • South Australia
    • North West Province
      • Mintabie district
Brazil
 
  • Pará
    • São Geraldo do Araguaia
H. Henriques
Honduras
Banerjee and Wenzel (1999)
Mexico
 
  • Hidalgo
    • Mun. de Zimapán
Coenraads and Zenil (2006)
  • Jalisco
    • Mun. de Magdalena
Michelou (2006)
USA
 
  • Oregon
    • Lake Co.
Laurs and Quinn (2003)
    • Morrow Co.
Holzhey (1997)
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.