While comparing Hercynite and Plumbogummite 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 Hercynite and Plumbogummite chemical formula.
Another important criteria for qualitative analysis of gemstones is Hercynite and Plumbogummite Specific gravity. Specific gravity is the relative density of a gemstone compared with respect to density of water. Gemologists use Hercynite and Plumbogummite Optical Properties during the identification of gemstone. Specific gravity of Hercynite is 4.014 whereas that of Plumbogummite is 4.014.