While comparing Precious Opal and Snowflake Obsidian 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 Precious Opal and Snowflake Obsidian chemical formula.
Another important criteria for qualitative analysis of gemstones is Precious Opal and Snowflake Obsidian Specific gravity. Specific gravity is the relative density of a gemstone compared with respect to density of water. Gemologists use Precious Opal and Snowflake Obsidian Optical Properties during the identification of gemstone. Specific gravity of Precious Opal is 2.33-2.50 whereas that of Snowflake Obsidian is 2.33-2.50.