Know all about Coal and Rhyodacite properties here. All properties of rocks are important as they define the type of rock and its application. Coal belongs to Sedimentary Rocks while Rhyodacite belongs to Igneous Rocks.Texture of Coal is Amorphous, Glassy whereas that of Rhyodacite is Earthy. Coal appears Veined or Pebbled and Rhyodacite appears Skeletal. The luster of Coal is dull to vitreous to submetallic while that of Rhyodacite is greasy to dull. Coal is available in black, brown, dark brown, grey, light to dark grey colors whereas Rhyodacite is available in black to grey, dark greenish - grey colors. The commercial uses of Coal are alumina refineries, electricity generation, liquid fuel, manufacture of soap, solvents, dyes, plastics and fibres, paper industry and that of Rhyodacite are cemetery markers, creating artwork.