sedimentary rock

• Clastic sedimentary rocks are formed by the buildup of numerous pieces of other rocks, which are cemented together by compaction, or the infiltration of some other mineral. They are usually classified by particle size:

  • Sandstone
  • Greensand (aka Marl)
  • Mudstone
  • Siltstone
  • Shale
  • Arkose

  Some are of mixed particle size, classified by particle shape:

  • Conglomerate
  • Breccia
  
  
  
• Organically-formed sedimentary rocks are essentially accumulated organic matter: Material excreted by organisms, or left behind after their death.
  
  • Coal
  • (Some) Limestone e.g.
    • Stromatolites
    • Chalk
    • Coral
  
  
  
• Chemically-formed sedimentary rocks are the result of chemical processes in the deep ocean, or in soils:
  • Chert (with variations like Agate, Chalcedony, and Flint)
  • Limestone including varieties such as
    • Dolomite
    • Oolite
  • Duricrusts such as Laterite (aka ironstone) and Bauxite

I thought it was a cool idea...