Rocks

• Rocks


  Naturally occurring solid masses composed of minerals
• Monomineralic rocks


  Rocks composed of only one mineral
• Monomineralic rocks

  • Limestone
  • Marble
• Monomineralic Rocks

  Composed of only one mineral
• Igneous


  Originates from the Latin word 'ignis', which means 'fire'
• Magma


  Molten rock material that is mostly formed in the Earth's mantle
• Lava


  Magma that has reached the surface of the Earth
• Intrusive, also known as Plutonic rocks

  Igneous rocks formed beneath the Earth's surface
• Extrusive, also known as Volcanic rocks


  Igneous rocks formed at the surface
• Dark silicate minerals


  Rich in iron and/or magnesium, and low in silica
• Light silicate minerals


  Rich in potassium, sodium, and calcium, and rich in silica
• Granitic igneous rocks


  FELSIC = feldspar + silica, and contains around 10% of dark silicates
• Basaltic igneous rocks


  MAFIC = magnesium + ferrum (iron), and contains at least 45% dark silicate minerals
• Andesite


  Contains at least 25% dark silicate minerals + other minerals (plagioclase and feldspar)
• Ultramafic group rocks


  Mainly composed of olivine and pyroxene, almost entirely of ferromagnesian minerals (iron and magnesium)
• Texture

  The overall appearance of rocks based on the size, shape, and arrangement of the mineral grains
• Texture


  Indicates the cooling rate of the magma, which affects the size of the crystals
• Fine-grained rocks


  Result from very fast cooling, which allows less time for the crystals to form
• Coarse-grained rocks


  Result from slow cooling of the magma at a great depth
• Porphyritic rocks


  Large crystals embedded in a bed of smaller crystals, composed of two distinct sizes of minerals
• Vesicular rocks


  Formed due to different rates of cooling of molten rocks
• Vesicles


  The holes in Vesicular rocks
• Vesicles


  Due to the gas bubbles that escaped as the lava solidifies
• Glassy rocks


  Formed when a volcanic material is ejected into the atmosphere and cools quickly
• Glassy rocks


  Smooth and shiny, due to the particles (ions) being frozen in place without time to combine in an orderly manner to form a crystalline structure
• Pyroclastic rocks


  Formed from the merging of individual rock fragments or pyroclastic materials ejected during an explosive volcanic eruption
• Sedimentary Rocks


  Formed from pre-existing rocks, minerals, and remains of living things
• Sediments


  The bits and pieces of materials that form Sedimentary Rocks
• Weathering


  The process of breaking down or dissolving rocks in the formation of Sedimentary Rocks
• Erosion


  The process in which earthen materials are worn away and transported by natural forces such as wind or water
• Deposition


  The laying down or dropping of sediment in a new place by wind or water
• Lithification


  The process in which sediments compact under pressure and gradually transform into solid sedimentary rocks
• Detrital sedimentary rocks


  Made up of clay minerals and quartz, formed from fragments of weathered rocks
• Types of detrital sedimentary rocks based on particle size

  • Coarse (over 2 mm)
  • Medium (1/16 to 2 mm)
• Rocks with rounded and angular gravel particles

  • Conglomerate
  • Breccia
• Rocks with sand and sand abundant in feldspar

  • Sandstone
  • Arkose
• Siltstone


  Composed of clay-sized sediment mixed with slightly larger silt-sized grains
• Shale / Mudstone


  Mainly composed of clay minerals
• Chemical sedimentary rocks


  Formed from the chemical depositing of materials that were in the water
• Crystalline Limestone


  Composed of calcite, Calcium Carbonate (CaCO3)