While comparing Nepheline and Gedrite 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 Nepheline and Gedrite chemical formula.
Another important criteria for qualitative analysis of gemstones is Nepheline and Gedrite Specific gravity. Specific gravity is the relative density of a gemstone compared with respect to density of water. Gemologists use Nepheline and Gedrite Optical Properties during the identification of gemstone. Specific gravity of Nepheline is 3.15-3.259 whereas that of Gedrite is 3.15-3.259.