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