Common Opal and Onyx Physical Properties
Tenacity
Not Available
  
Not Available
  
Solubility
Not Available
  
Not Available
  
Durability
Not Available
  
Not Available
  
Specific Gravity
1.98-2.50
  
2.55-2.70
  
Fracture
Conchoidal, Conchoidal, Gemstones of the world (2001)
  
Not Available
  
Cleavage
Not Available
  
Indiscernible
  
Mohs Hardness
5.5-6.5
  
6.5-7
  
Chemical Composition
SiO 2 · nH 2OWalter Schumann , Gemstones of the world (2001)
  
SiO2
  
Common Opal and Onyx Chemical Formula
While comparing Common Opal and Onyx physical properties, the important data you should know is its chemical composition. Since chemical formula defines the molecular structure of the crystal, most of the physical properties like color, tenacity, solubility are governed by Common Opal and Onyx chemical formula.
- Chemical formula of Common Opal- SiO 2 · nH 2OWalter Schumann , Gemstones of the world (2001)
- Chemical formula of Onyx- SiO2
Common Opal and Onyx Specific Gravity
Another important criteria for qualitative analysis of gemstones is Common Opal and Onyx Specific gravity. Specific gravity is the relative density of a gemstone compared with respect to density of water. Gemologists use Common Opal and Onyx Optical Properties during the identification of gemstone. Specific gravity of Common Opal is 2.55-2.70 whereas that of Onyx is 2.55-2.70.