Properties of Greywacke and Coal play an important role in determining the type of rock. Along with Greywacke vs Coal properties, get to know more about Greywacke Definition and Coal Definition. For the ease of understanding, the properties of rocks are divided into physical and thermal properties. Rocks have a variety of properties like hardness, color, specific gravity, fracture, cleavage, luster etc. Know all about physical and thermal properties of Greywacke and Coal.