While comparing Pyrite Marcasite and Selenite 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 Pyrite Marcasite and Selenite chemical formula.
Another important criteria for qualitative analysis of gemstones is Pyrite Marcasite and Selenite Specific gravity. Specific gravity is the relative density of a gemstone compared with respect to density of water. Gemologists use Pyrite Marcasite and Selenite Optical Properties during the identification of gemstone. Specific gravity of Pyrite Marcasite is Not Available whereas that of Selenite is Not Available.