Moss Opal

Common opal with moss-like inclusions (generally fine-grained chlorite, often mixed with clay minerals).
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)
Physical Properties of Moss Opal
Mohs Hardness5.5 to 6.5
Walter Schumann, Gemstones of the world (2001)
Specific Gravity1.98 to 2.50
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)
Optical Properties of Moss Opal
Refractive Index1.37 to 1.52
Walter Schumann, Gemstones of the world (2001)
BirefringenceNone
Walter Schumann, Gemstones of the world (2001)
PleochroismAbsent
Walter Schumann, Gemstones of the world (2001)
Colour
Colour (General)Milky
Walter Schumann, Gemstones of the world (2001)
TransparencyTranslucent,Opaque
Walter Schumann, Gemstones of the world (2001)
Crystallography of Moss Opal
Crystal SystemAmorphous
Walter Schumann, Gemstones of the world (2001)
Inclusions in Moss Opal
Generally fine-grained chlorite, often mixed with clay minerals. - Opal, Lithographie, 2007, p. 59
Further Information
Mineral information:Moss Opal information at mindat.org
Significant Gem Localities
USA
 
  • Oregon
    • Lake Co.
Laurs and Quinn (2003)
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