Know all about Coal and Tachylite properties here. All properties of rocks are important as they define the type of rock and its application. Coal belongs to Sedimentary Rocks while Tachylite belongs to Igneous Rocks.Texture of Coal is Amorphous, Glassy whereas that of Tachylite is Vitreous. Coal appears Veined or Pebbled and Tachylite appears Glassy. The luster of Coal is dull to vitreous to submetallic while that of Tachylite is resinous. Coal and Tachylite are available in black, brown, dark brown, grey, light to dark 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 Tachylite are cemetery markers, creating artwork.