Rocks and Rock Cycle

• Rocks


  Natural occurring solid matter and aggregate of one or more minerals or mineral like materials
• Minerals


  • Categorized by: luster, color, streak, hardness, cleavage, specific gravity
• Bedrock


  Mass of consolidated rocks that has not been weathered
• Regolith


  Broken and decomposed rock fragments
• Outcrop


  Mass of exposed bedrock
• Magma


  Molten rock matter beneath the Earth's surface
• Lava


  Molten rock mineral at the surface
• 98% of the earth's crust is made of eight elements
• Most common rock forming minerals are silicates which are composed primarily of oxygen and silicon
• Rock Forming Minerals


  • Plagioclase feldspar
  • Potassium feldspar
  • Quartz
  • Muscovite
  • Biotite
  • Amphibole
  • Pyroxene
  • Olivine
  • Calcite
  • Dolomite
  • Hematite
  • Halite
  • Gypsum
  • Talc
  • Chlorite
• Igneous Rocks


  Formed from the solidification and cooling of magma from molten rock minerals, usually hard and crystalline
• Volcanic/Extrusive Rocks


  • Result of magma reaching the surface either as lava or fragmental eject, forming rocks
  • When magma reaches the surface, it cools quickly and forms small crystals which are the volcanic or extrusive igneous rocks
  • Examples: basalt, obsidian, andesite, rhyolite, pumice
• Plutonic/Intrusive Rocks


  • Result when magma cools and crystallizes within the Earth's crust
  • Magma doesn't always reach the surface and sometimes gets trapped under, they form large crystals and becomes the intrusive or plutonic rocks as it cools down slowly
  • Examples: granite, gabbro, pegmatite, periodite
• Rate of cooling


  Controls the crystal size in igneous rocks
• Crystal


  Special kind of solid materials where molecules fit together in a repeating pattern
• Sedimentary Rocks


  Formed by deposition of material at the Earth's surface and or within bodies of water
• Types of Sediments


  • Detrital
  • Chemical
  • Organic
• Sedimentation


  Processes that cause mineral and/or organic particles to settle and accumulate or minerals to precipitate to form a solution
• Lithification


  All processes which convert unwanted sediments into sedimentary rocks
• Deposition


  Sediments, soil, and rocks, are added to a landform or mass
• Compaction


  Porosity of a given form of sediment is decreased due to mineral grains being squeezed together by the weight of overlying sediment or by mechanical means
• Cementation


  Binding of particles or other things by cement
• Types of Sedimentary Rocks

  • Clastic Sedimentary
  • Chemical/Crystalline Sedimentary
  • Organic/ Biochemical Rocks
• Metamorphic Rocks


  Arise from the transformation of existing rock types, in a process called metamorphism
• Metamorphism


  Change of minerals of geologic texture (distinct mineral arrangement) in pre-existing rocks without melting
• Foliation in Metamorphic Rocks

  Foliated metamorphic rocks present platy surfaces or wavy alignment of light and dark minerals that formed during metamorphism
• Classification of Metamorphic Rocks

  • Texture
  • Mineralogical
  • Chemical
• The Rock Cycle


  1. Magma cools down and form igneous rocks

  2. Igneous rocks broken down into sediments through weathering, erosion, and deposition

  3. Sediments transported in bodies of water, go through sedimentation, compaction, and cementation forming sedimentary rocks

  4. Buried sedimentary rocks subjected to heat and pressure turn into metamorphic rocks

  5. Further exposure to heat and pressure can turn metamorphic rocks to magma and the process repeats
• Processes Involved in the Rock Cycle

  • Heat and Pressure
  • Melting
  • Weathering and Erosion
  • Compacting and Cementing
  • Cooling and Crystallization
• Uses of Rocks

  • Source of minerals
  • Used in construction
  • Good sources of water
  • Ornamental source
  • Abrasive cleansing product
  • Jewelry
  • Form mountains
  • Tiles, roof bricks, wall, counter or tabletops