ES0701  Observe an animation showing coal form.
  !   Click the image to see the animation. Use the movie controls to examine the sequence.
  • Plant materials buried under sediments decay to form peat, a compressed mass of plant remains.

  • Compaction forces water out of the sediments to form lignite, a soft, brown coal.

  • Further compression and aging turn lignite into bituminous coal, a soft, black coal.

  • Heat and pressure metamorphose bituminous coal to anthracite, a hard coal that is almost pure carbon.

Jennifer Loomis, TERC