While comparing Copper and Erythrite 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 Copper and Erythrite chemical formula.
Another important criteria for qualitative analysis of gemstones is Copper and Erythrite Specific gravity. Specific gravity is the relative density of a gemstone compared with respect to density of water. Gemologists use Copper and Erythrite Optical Properties during the identification of gemstone. Specific gravity of Copper is 3.06 whereas that of Erythrite is 3.06.