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Carnelian

Carnelian is probably named after the colour of the kornel cherry because of its colour. It is brownish red to orange, translucent to opaque Chalcedony variety.
When held against the light, the colour variety shows stripes, natural carnelian shows a cloudy distribution of colour.
General Information
A variety or type of:Chalcedony, which is a variety of Quartz
Other Names/Trade Names:
Cornelian
Chemical Formula
SiO
 
2
Gemdat.org, Management Team (2012)
Carnelian Treatments
The colour can be enhanced by heating. - Gemstones of the world, Walter Schumann, 2001, p 126
Carnelian Simulants
Most carnelians offered today are agates which are dyed and then heat-treated. - Gemstones of the world, Walter Schumann, 2001, p 126
Physical Properties of Carnelian
Mohs Hardness6.5 to 7
Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010)
Specific Gravity2.58 to 2.64
Walter Schumann, Gemstones of the world (2001)
More from other references
Cleavage QualityNone
Walter Schumann, Gemstones of the world (2001)
FractureUneven
Walter Schumann, Gemstones of the world (2001)
Optical Properties of Carnelian
Refractive Index1.535 to 1.539
Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010)
Optical CharacterUniaxial/+
Ulrich Henn and Claudio C. Milisenda, Gemmological Tables (2004)
Birefringence0.003 to 0.009
Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010)
PleochroismAbsent
Walter Schumann, Gemstones of the world (2001)
DispersionNone
Walter Schumann, Gemstones of the world (2001)
Colour
Colour (General)Red, orange, reddish
Gemdat.org, Management Team (2012)
Causes of ColourOrange to red, submicroscopic to microscopic inclusions of hydrous Fe oxides
W. William Hanneman, Pragmatic Spectroscopy For Gemologists (2011)
TransparencyTranslucent,Opaque
Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010) Semi-transparent to opaque
LustreWaxy,Resinous
Arthur Thomas, Gemstones (2009)
Fluorescence & other light emissions
Fluorescence (General)Blue-white
Walter Schumann, Gemstones of the world (2001)
Crystallography of Carnelian
Crystal SystemTrigonal
Ulrich Henn and Claudio C. Milisenda, Gemmological Tables (2004)
HabitFibrous to grained aggregate
Ulrich Henn and Claudio C. Milisenda, Gemmological Tables (2004)
Further Information
Mineral information:Carnelian information at mindat.org
Significant Gem Localities
Sri Lanka
 
  • Sabaragamuwa Province
    • Ratnapura District
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