While comparing Franklinite and Hiddenite 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 Franklinite and Hiddenite chemical formula.
Another important criteria for qualitative analysis of gemstones is Franklinite and Hiddenite Specific gravity. Specific gravity is the relative density of a gemstone compared with respect to density of water. Gemologists use Franklinite and Hiddenite Optical Properties during the identification of gemstone. Specific gravity of Franklinite is 3.15-3.21 whereas that of Hiddenite is 3.15-3.21.