Lithosphere

• Lithosphere


  The solid outer layer of the Earth, consisting of the crust and upper mantle
• Mineral Resources


  • Fossil fuels
  • Metal ores
  • Non-metal minerals
• The most important mineral resources

  • Oil
  • Bitumen
  • Clay
  • Coal
  • Glass-sand
  • Granite
  • Iron-ore
  • Lead/zinc
  • Gold
• Geological origins of economically important minerals

  1. If all the minerals in the crust were evenly mixed, none would be sufficiently concentrated to allow exploitation

  2. Geological processes have provided local concentrations that can be exploited

  3. An understanding of the processes that produced them can help show which other geological formations would be expected in the surrounding areas
• Igneous processes


  1. Plates in the crust are moved by convection currents in the mantle

  2. Friction, heat and pressures produce molten rock called magma that is forced up towards the surface

  3. Magma may reach the surface as an igneous extrusion and cool rapidly to form fine-grained rock

  4. Magma may fail to reach the surface, forming a large molten mass of intrusive rock that cools slowly, producing larger crystals and allowing minerals to separate into localised concentrations

  5. Hydrothermal metal ore deposits form around batholiths as mineral-rich hot solutions travel along cracks and fissures and deposit minerals as they cool
• Sedimentary processes


  1. Existing rock is broken down by weathering and eroding into smaller particles and dissolved minerals

  2. These are carried away, separated and redeposited elsewhere as rocks with different compositions and properties

  3. Alluvial/Placer deposits - carried by flowing water and deposited when flow slows down

  4. Evaporites - formed when water evaporates from mineral-rich solutions and minerals crystallise

  5. Biological deposits - produced from dead animals and plants, e.g. fossil fuels

  6. Chemical precipitates - e.g. manganese nodules on deep sea beds
• Metamorphic processes


  Existing rock is exposed to extreme heat and pressure from nearby igneous activity, changing form without melting
• Minerals are non-renewable
• Resources


  Include all the material which is theoretically available to exploit, including deposits we can't access now
• Reserves


  That portion of the resource we can exploit now, economically, using existing technology
• Factors affecting the viability of mining

  • Extraction costs
  • Processing costs
  • Transport costs
  • Market economics
  • Land conflicts
• Extraction costs


  • Depth of deposit
  • Overburden quality
  • Drainage problems
  • Size and form of deposits
• Processing costs


  • Chemical form of deposit
  • Purity of deposit
  • Cut-off ore grade
• Transport costs


  • Existing infrastructure
  • Distance from market
• Cut-off ore grade


  Lowest purity of ore that can be exploited economically
• Market price of mineral is determined by demand and how much is produced
• Supplies rise and fall slowly, but demand can rise and fall quickly
• Competing land uses may be more important or valuable than mining, e.g. urban areas, conservation areas
• Environmental impacts of mining, quarrying and dredging

  • Exploration disturbance
  • Land impacts
  • Habitat loss
  • Loss of amenity
  • Dust
  • Noise
  • Turbid drainage water
  • Toxic leachate
  • Spoil disposal
  • Subsidence
  • Transport nuisance
  • Flooding
  • Ore processing waste disposal
• Methods used to reduce environmental impacts

  1. Landscaping

  2. Water sprays

  3. Baffle mounds/embankments

  4. Sedimentation lagoons

  5. Leachate collection

  6. Acid neutralisation

  7. Spoil compaction

  8. Alternative transport routes
• Mineral resources are very abundant but reserves of exploitable minerals are limited
• Methods used to extend the time period of exploitation

  1. More exploration in previously unexplored areas

  2. Better exploratory techniques like remote sensing, gravimetry, magnetometry, seismic surveys, core sampling

  3. Better or more mechanised extraction techniques

  4. Use of low grade ores

  5. Recycling

  6. Substitution with alternative materials