the lithosphere

• Hydrothermal deposition involves igneous intrusions producing pressurised superheated water at high temperatures that dissolves minerals from surrounding rocks
• Mineral-rich solutions travel along fissures away from the igneous batholith, cooling as they do so
• Dissolved minerals crystallise in order of their solubility, with the least soluble crystallising first
• Metal ores deposited by hydrothermal processes include tin, copper, lead, silver, gold, and arsenic
• Metamorphic processes can alter existing rocks with high temperatures and pressure, without melting them, producing metamorphic rocks
• High temperatures and extreme pressure can change limestone to marble
• Extreme pressure can change mudstone to slate
• Sedimentary processes cause minerals to settle and build up to produce layers of deposited sediment, creating sedimentary rocks and minerals
• Alluvial processes involve materials carried and separated by flowing water, including gold, diamonds, tin ore, gravel, sand, and clay
• Lasky's principle states that as the purity of a mineral decreases, the amount of the mineral present increases exponentially
• Stock (resource base) includes all material in the lithosphere that can be exploited now, in the future, or never
• Resource is larger than reserves and includes all material theoretically available for exploitation
• Reserves are the amount of the resource that can be exploited now, economically, using existing technology
• Factors affecting mining viability include ore purity, chemical form, overburden, depth, cut-off ore grade, transport costs, and market economics
• Survey techniques include IR spectroscopy, gravimetry, magnetometry, seismic surveys, resistivity, trial drilling, and chemical analysis
• Exploitation methods include mechanisation, deep mining, open-cast mining, exploitation of low-grade deposits, bioleaching, phytomining, iron displacement, leachate collection, rare earth metals extraction, polymer adsorption, and recycling
• Cradle to Cradle design aims to extend the lifetime of minerals by designing products for reuse at the end of their useful lives
• Igneous intrusions are rocks formed from magma that cools and solidifies within the Earth's crust
• Intrusions produce pressurised superheated water at high temperatures that dissolves many minerals from the surrounding rocks
• Mineral-rich solutions travel along fissures away from the igneous batholith, cooling as they do so
• As they cool, dissolved minerals crystallise and come out of solution in order of their solubility
• Fractional crystallisation starts with a mixture of minerals that could not have been exploited
• Metal ores deposited by hydrothermal processes include tin, copper, lead, silver, gold, and arsenic
• Metamorphic processes can alter existing rocks with high temperatures and pressure, without melting them, producing metamorphic rocks
• High temperatures and extreme pressure can change limestone to marble
• Extreme pressure can change mudstone to slate
• Sedimentary processes

  Sedimentary processes cause minerals to settle and build up to produce layers of deposited sediment. This deposition and subsequent cementation at the Earth's surface and within bodies of water creates sedimentary rocks and minerals.
• Alluvial deposits

  Alluvial processes involve materials that were carried and separated by flowing water. The ability of water to carry solids depends upon the velocity of the water and the density of the solids. Materials that are exploited from alluvial deposits include gold, diamonds, tin ore, gravel, sand, clay.
• Lasky's principle

  Lasky's principle states that: in general, as the purity of a mineral decreases, the amount of the mineral present increases exponentially.
• Stock (also called resource base)

  This includes all of the material that exists in the lithosphere. It includes the mineral that can. be exploited now, that which will be exploitable when prices rise, or new technologies are developed and that which will never be technologically or economically exploitable.
• Resource

  The resource is larger than the reserves as it includes all the material that is theoretically available for exploitation. This includes deposits that can be exploited (the reserves) plus those that cannot be exploited now but with realistic increases in prices, or improvements in technology, could be extracted in the future. Resources that are deep, low grade, in a difficult chemical form, or in locations that are currently protected, could all become usable in the future.
• Reserves are defined as the amount of the resource that can be exploited now, economically, using existing technology
• The size of the resource is finite, but the quantity counted in the reserves can change based on economic factors
• If the market price for the resource increases or new extraction technologies become economically viable, then the reserves will increase
• If market prices fall, reserves may decrease
• Factors that limit the viability of exploitation:

  • Absence of technology to exploit the deposits
  • Financial cost of exploitation may be too great
  • Environmental impact of exploitation may be unacceptable
• The purity of the ore affects the financial costs of exploitation and the environmental impacts of mining.

  •   If the ore grade is low then:
  •   more rock will have to be mined;
  •   more waste materials (spoil) will be produced;
  •   more energy will be needed for mining and processing;
  •   more pollution will be generated.
• Chemical form

  The chemical form of the mineral ore affects the ease of chemical extraction of the metal.

  For example, aluminium can be extracted from bauxite (aluminium oxide) but not from clay (alumino-silicates) which is much more abundant.
• Overburden and hydrology

  The overburden is the rock that lies above a mineral deposit. Hard overburden may require blasting which increases costs. Loose overburden may increase the risk of landslides, so the sides of the mine void may have to be landscaped at a more gentle gradient. This may increase the overall area of the mine. Higher precipitation or impermeable rocks below may increase drainage costs.
• Depth

  Costs rise rapidly as the depth increases. If the depth is doubled then the cost much more than doubles. The sides of the mine cannot be vertical because of the risk of collapse. So the amount of rock that must be removed to reach the mineral rises rapidly as depth increases.