Opal and Coral Physical Properties
Tenacity
BrittleWalter Schumann
  
Not Available
  
Solubility
hot salt water
  
Not Available
  
Durability
Not Available
  
Not Available
  
Specific Gravity
1.98-2.25
  
2.60-2.70
  
Fracture
Conchoidal, Conchoidal, Gemstones of the world (2001) More from other references, Brittle
  
Irregular, Irregular, Gemstones of the world (2001)
  
Cleavage
None
  
Not Available
  
Mohs Hardness
5-6.5
  
3-4
  
Chemical Composition
SiO2 · nH2O
  
CaCO 3Ulrich Henn and Claudio C.
  
Opal and Coral Chemical Formula
While comparing Opal and Coral 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 Opal and Coral chemical formula.
- Chemical formula of Opal- SiO2 · nH2O
- Chemical formula of Coral- CaCO 3Ulrich Henn and Claudio C.
Opal and Coral Specific Gravity
Another important criteria for qualitative analysis of gemstones is Opal and Coral Specific gravity. Specific gravity is the relative density of a gemstone compared with respect to density of water. Gemologists use Opal and Coral Optical Properties during the identification of gemstone. Specific gravity of Opal is 2.60-2.70 whereas that of Coral is 2.60-2.70.