Earth & Space

• Rock: A naturally occurring collection made up of two or more minerals.
• Mineral: A naturally occurring substance with its own chemical properties, composition, and structure.
• Crystal: A small, organised particle in rocks which has smooth sides and sharp edges.
• Ore: A rock containing a large amount of useful material
• Colour: The visible colour a mineral sample appears to the naked eye.
• Streak: The colour of a mineral in its powdered form.
• Lustre: The way the light reflects off a mineral's surface. (two types: metallic and non-metallic.)
• Breakage: The way a mineral sample tends to break.
• There are two types of breakage: cleavage and fracture.
• Cleavage: When a mineral breaks, it does so along the smooth planes which are parallel.
• Fracture When a mineral breaks, it does so along the curved surfaces without a definite shape.
• Hardenss: A measure of how easily a mineral can be scratched (measured by Moh's Hardness Scale)
• Intrusive igneous rocks:

  • Formed underneath the ground
  • Formed from magma
  • Slow cooling
  • Large crystals
• Extrusive igneous rocks:

  • Formed from lava
  • Fast cooling
  • Small crystals
• Basalt, obsidian and pumice are extrusive igneous rocks
• Granite is an intrusive igneous rock
• Sedimentary rocks: Rocks formed from the accumulation and cementation of organic materials over a long period of time.
• The three types of sedimentary rocks are: chemical, clastic and biological/organic
• Clastic: Made of broken pieces of other rocks cemented together
• Chemical: Formed when minerals dissolve into water and harden.
• Organic/biological: Formed from the remains of plants and/or animals and often contain fossils.
• Basalt

  • Extrusive igneous
  • Dense and dark coloured
  • Used for construction
• Granite

  • Intrusive igneous
  • Hard with quartz, feldspar and mica
  • Used for construction
• Pumice

  • Extrusive igneous
  • Light grey with tiny air pockets
  • Floats on water
  • Used to clean dead skin off feetA
• Obsidian

  • Extrusive igneous
  • Dark with smooth sides and sharp edges
  • Not a crystal because it cools quickly
  • Used in jewellery
• Limestone

  • Biological/chemical sedimentary
  • Made of calcium carbonate
  • Used for construction
• Sandstone

  • Clastic
  • Made of layers of sand and can have quartz
  • Used for construction
• Shale

  • Clastic
  • Layered appearance
  • Used for oil production
• Conglomerate

  • Clastic sedimentary
  • Coarse-grained
  • Used for construction
• Igneous rocks are formed from the solidification and cooling of magma or lava.
• There are two types of igneous rocks: extrusive and intrusive
• What is the difference between igneous and sedimentary rocks?


  Igneous rocks are formed from the solidification of magma or lava, while sedimentary rocks are formed from the accumulation and cementation of organic materials.
• Fossil: Preserved remains of dead organisms from millions of years ago
• Fossils are usually sedimentary rocks
• Metamorphic rock forms when existing rocks change due to heat and pressure
• Contact Metamorphism occurs when hot magma comes into contact with an existing rock
• Regional metamorphism happens over large areas where there is high pressure and temperature
• Fossils are formed from near-perfect geological conditions.

  1. The organism must die
  2. The organism is buried by ash, sand or sediment
  3. Over millions of years through processes such as sedimentation, erosion and weathering, the organism is slowly fossilised into a rock/fossil
• Index fossils: Fossils that are used to determine the age of other fossils.

  They must be:

  1. Abundant
  2. Widespread globally
  3. Only lived for a short period of time in the past.
• Granite —> Gneiss