• Need to know: Rocks

    Igneous Rocks

    Monominerallic- a rock made from one mineral (i.e. Dunite)

    Polyminerallic- a rock made from more than one mineral. (i.e. Granite)

    • Fire Formed- melted rock material cools and solidifies (freezing)
    • Intrusive- rock formed inside the Earth (like Granite)
    • Extrusive- rock formed on the surface  (like Obsidian)
    • Texture- the size of the crystals- NOT HOW IT FEELS

    Intrusive

    Extrusive

    Rocks INSIDE the Earth Rocks OUTSIDE the Earth
    Plutonic Volcanic
    Formed from magma Formed from lava
    Crystals grow large Crystals are small or not there at all!

    Examples:

    Examples:

    Granitegranite

    Obsidianobsidian

    Gabbro

    Pumice

    Pegmatite

    Scoria

    A major characterisitc to look for in an Igneous rock: Intergrown Crystals

    Intergrown...
    granite(Granite)

    SEDIMENTARY ROCKS:

    Made from sediments or rock material that has been broken down in some way.

    • Water is usually involved in forming sedimentary rocks.
    • Fragments/sediments of various sizes make up a variety of sedimentary rocks.
    • Sedimentary rocks are the only rocks that contain fossils!

    Types of Sedimentary Rocks

    • Clastic (fragmental) made by compaction and cementation of sediments.
      • Clastic rocks are identified by the size of the fragments.
      • Conglomerate has rounded fragments...
      conglom
     
    Breccia has angular fragments:
    breccia
     
    -
    Chemically formed rocks: evaporites
    • Formed when water carrying minerals evaporates and leaves the minerals behind.
  • Bioclastic-
    • bio= life
    • clastic= fragments
  • Made from accumulated shells (limestone) or plants (coal)


    METAMORPHIC ROCKS-

  • changed from a pre-existing rock
  • caused by extreme heat and/or pressure
  • may result in a distorted structure like this... distorted

    Foliation is a grain to the rock.

    Gneissic Foliation

    • minerals are squished into bands.
    • Zebra Stripes 
    •  gneiss
    •  
    • Schistose foliation- minerals have been squashed into flakes of mica. Like in this sample of schist:sch
    • or... HOLEY SCHIST:holes sch
  • The rocks can change between each type by following processes that are described in the rock cycle. See page 6 of your ESRT.
    Special thanks to Mr. Phil Medina for images and inspiration.

     

Last Modified on October 11, 2011