Onyx and Common Opal Physical Properties

Onyx and Common Opal Chemical Formula

While comparing Onyx and Common Opal 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 Onyx and Common Opal chemical formula.

• Chemical formula of Onyx- SiO₂
• Chemical formula of Common Opal- SiO 2 · nH 2OWalter Schumann , Gemstones of the world (2001)

Onyx and Common Opal Specific Gravity

Another important criteria for qualitative analysis of gemstones is Onyx and Common Opal Specific gravity. Specific gravity is the relative density of a gemstone compared with respect to density of water. Gemologists use Onyx and Common Opal Optical Properties during the identification of gemstone. Specific gravity of Onyx is 1.98-2.50 whereas that of Common Opal is 1.98-2.50.