Types of Rocks

• There are 3 types of rocks found on Earth:

  • Igneous
  • Sedimentary
  • Metamorphic
• Igneous Rocks -

  • When a molten rock material cools and solidifies it becomes an igneous rock. 
  • Igneous comes from word “ignis” meaning fire.
  • Igneous Rocks are formed by melting, cooling, and crystallization of other rocks.
• Igneous Rocks are  formed by crystallization from a liquid, or magma. They include two types:

  1. Extrusuve igneous rocks cool quickly and as a result these rocks are fine grained or has lack of crystal growth.
  2. Intrusive igneous rocks are forms from magma that cools slowly and as a result these rocks are coarse grained.
• Igneous Rocks are  formed by crystallization from a liquid, or magma. They include two types:

  1. Extrusuve igneous rocks cool quickly and as a result these rocks are fine grained or has lack of crystal growth. Cooling time: seconds to months. Texture: invisible or microscopic grains
  2. Intrusive igneous rocks are forms from magma that cools slowly and as a result these rocks are coarse grained. Cooling time: thousand of years. Texture: small-to-medium grains.
  3. Plutonic- Cooling time: millions of years. Texture: large grains.
• Types of rocks


  • Igneous
  • Sedimentary
  • Metamorphic
• Igneous rocks


  Formed by melting, cooling, and crystallization of other rocks
• Formation of igneous rocks

  1. Melting

  2. Cooling

  3. Crystallization
• Where igneous rocks form

  • Along plate boundaries or mantle hot spots
  • At divergent boundaries like mid-ocean ridges
  • At subduction zones
  • At continental-continental convergent boundaries
• Texture


  Describes the appearance of an igneous rock based on the size, shape, and the arrangement of its interlocking crystals
• Igneous rock textures


  • Glassy
  • Aphanitic
  • Phaneritic
• Composition refers to the elements in the magma that is directly affects the kind of mineral that is formed when magma cools. The mineral color varies with silica (SiO2) content
• Magma composition


  • Felsic
  • Intermediate
  • Mafic
• Plutonic vs volcanic


  Plutonic igneous rocks form by slow cooling below ground

  Volcanic igneous rocks form by fast cooling above ground
• Sedimentary rocks


  Formed by weathering, erosion, deposition, compaction, and cementation of other rocks
• Formation of sedimentary rocks

  1. Weathering

  2. Erosion

  3. Deposition

  4. Compaction

  5. Cementation
• Types of sedimentary rocks

  • Clastic
  • Chemical
  • Organic
• Clastic sedimentary rocks


  Derived from mechanical weathering and breakdown of rocks into smaller pieces
• Clastic sedimentary rocks


  • Conglomerate
  • Sandstone
  • Mudrock
• Chemical sedimentary rocks


  Form when dissolved minerals come out of solution
• Organic sedimentary rocks


  Composed of materials formed by the activity of living organisms
• Subduction zones occur whenever a dense oceanic plate is subducted underneath another oceanic or continental plate.
• Glassy igneous rocks have no crystal structure, and probably formed by very rapid cooling (such as on the surface of a lava, or when a lava enters the water.)
• • Aphanitic rocks have no visible crystals, and probably formed by fast cooling above ground.
• • Phaneritic rocks have visible crystals, and probably formed by slow cooling below ground.
• • Light-colored rocks are silica-rich minerals.
• Dark-colored rocks are silica-poor minerals.
• Felsic magma rock

  • High silica-rich igneous rocks.
  • It has light-colored igneous rocks with few dark minerals.
  • 65% SiO2, low in Fe, Mg, Ca, high in K, Na.
• Intermediate magma rock

  • It has roughly even mixtures of felsic minerals and mafic minerals.
  • 55%-65% SiO2, intermediate. in Fe, Mg, Ca, Na, K
• Mafic magma rock

  • It has low silica content.
  • It has dark-colored  igneous rocks with few light minerals.
  • < 55% SiO2, high in Fe, Mg, Ca, low in K, Na 
• Identify

  A) Rhyolite

  B) Andesite

  C) Basalt

  D) Granite

  E) Diorite

  F) Gabbro

  G) Felsic Rocks

  H) Intermediate

  I) Mafic

  J) Volcanic

  K) Plutonic

  
• Plutonic rocks are formed when magma cools and solidifies underground. Volcanic rocks are formed from lava that flows on the surface of the Earth and other planets and then cools and solidifies.
• Classification

  
• Physical weathering is the breakdown of rocks by temperature changes and physical processes such as frost, water, and wind
• Chemical weathering is the breakdown of rocks through chemical reactions between the rock and its environment
• Biological weathering is the breakdown of rocks by living organisms.
• Erosion: the process of eroding or being eroded by wind, water, or other natural agents
• Weathering is the process of breaking down rocks and minerals into smaller pieces by water, wind, and ice. 
• Erosion is the process by which natural forces move weathered rock and soil from one place to another.  Gravity, running water, glaciers, waves, and wind all cause erosion.  The material moved by erosion is sediment
• Clastic sedimentary rocks derived from mechanical weathering which involves the breakdown of rocks into smaller ones at the surface of the crust.
• Lithification turns sediment into rock

  A) Deposition

  B) Compaction

  C) Cementation

  D) Lithification