Opal and Gypsum Physical Properties
Tenacity
BrittleWalter Schumann
  
Flexible
  
Solubility
hot salt water
  
Soluble
  
Durability
Not Available
  
Not Available
  
Specific Gravity
1.98-2.25
  
2.20-2.40
  
Fracture
Conchoidal, Conchoidal, Gemstones of the world (2001) More from other references, Brittle
  
Conchoidal, Splintery, Fibrous, UnevenArthur Thomas, Gemstones (2009)
  
Cleavage
None
  
Perfect on {010}, distinct on {100}
  
Mohs Hardness
5-6.5
  
2
  
Chemical Composition
SiO2 · nH2O
  
CaSO 4 -2(H 2O)Arthur Thomas , Gemstones (2009)
  
Opal and Gypsum Chemical Formula
While comparing Opal and Gypsum 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 Gypsum chemical formula.
- Chemical formula of Opal- SiO2 · nH2O
- Chemical formula of Gypsum- CaSO 4 -2(H 2O)Arthur Thomas , Gemstones (2009)
Opal and Gypsum Specific Gravity
Another important criteria for qualitative analysis of gemstones is Opal and Gypsum Specific gravity. Specific gravity is the relative density of a gemstone compared with respect to density of water. Gemologists use Opal and Gypsum Optical Properties during the identification of gemstone. Specific gravity of Opal is 2.20-2.40 whereas that of Gypsum is 2.20-2.40.