Know all about Coal and Greywacke properties here. All properties of rocks are important as they define the type of rock and its application. Coal and Greywacke belong to Sedimentary Rocks.Texture of Coal is Amorphous, Glassy whereas that of Greywacke is Clastic. Coal appears Veined or Pebbled and Greywacke appears Dull. The luster of Coal is dull to vitreous to submetallic while that of Greywacke is dull. Coal is available in black, brown, dark brown, grey, light to dark grey colors whereas Greywacke is available in beige, black, brown, colourless, cream, dark brown, green, grey, light green, light to dark grey, pink, red, white, yellow 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 Greywacke are as armour rock for sea walls, petroleum reservoirs, sea defence, tombstones.