The Lithosphere

The process by which rocks and minerals are created by the cooling and hardening og magma or molten lava

Igneous processes and tectonic movements of crustal plates can alter excisitng rocks with high temperatures and pressure without melting them producing metamorphic rocks

• Cause mineral to settle and build up to produce layers of deposited sediment • This deposition and subsequent cementation at the earths surface and within bodies of water creates sedenmentary rocks and minerals

• Involves materials that were carried and separated by flowing of water. • The ability of water to carry solids depends upon the velocity of water and density of the solids • Materials exploited from alluvial deposits are gold, dimonds, tin ore, gravel, sand and clay

• Biological processes are those where living from mineral deposits. • These processes often concentrate minerals that can be deposited in sedimentary rocks

• In general as the purity of a mineral decreases, the amount of mineral present increases exponentially • Major problem with future mineral supplies is not the quantity that exists but the need to develop methods to exploit low-grade deposits

The amount of a resource that can be exploited now, economically using excisting technology

• Includes all the material that is theoretically available for exploitation • It includeds deposits that can be exploited in the future with future technologies

• IR spectropasy • Gravimetry • Magnetromany • Seismic surveys • Resistivity • Trial drilling • Chemical analysis

Diffrent mierals emit infared radiation at diffrent wavelengths and these can be used to identify them

Gravimetry detects variations in gravity caused by variations in density and mass. Igneous rocks are usually more dense than sedimentry deposits

Magnetrometers detect rocks that are more magnetic such as the iron magnetite and ores of tungsten and cobalt

These involve sound waves produced by controlled exploitions, or a seismic vibraitor on the surface. The echoes can give information about depth, density and shape of rock starta

• The difficulty of with which electricity passes through a material • In general sedimentary rocks have lower resistivities than igneous rocks because they have a higher water content

• drone makes a grid of a map and then a hole is drilled down at ech coordinate to see of there is any deposit • The most expensive technique

• Labortory tests confirm the chemical composition and purity of the minerals in the rock samples

• Ore purity • Chemical form • Overburden and hydrology • Depth • Cut-off ore grade • Transport costs • Market economics

• Ore purity affects the financial costs of exploitation and enviromental impacts of mining If the ore grade is low then: - More rock will have to be mined - more spoil will be produced - More energy will be needed for mining and processing - More pollution will be generated

• Affects the ease of chemical extraction of the metal

• Hard overburden may require blasting which increases costs • Loose overburden increases the risk of landslides so the side of the mines may have to be landscaped at a mpre gental gradient • Higher percipitation or impermable rocks will increase drainage costs

• As depth increases so does the cost • Sides of the mine can not be verticle because the risk of collapse • As depth increases the amount of water entering the mine from runoff will also increase futher increasing water pumping costs ect

• Mining has to be an economically profitable activity so there must be a balnce between production cost and income • The lowest ore purity that can be mined economically using excisting technology is called the cut-off ore grade (COOG) • The COOG chnages as technology improves and market prices fluctuates

• Transport costs are affected by: • distance to market • weight of bulk • the presence of suitable existing transport infastructure

• Market prices are controlled by the demand of the mineral, how much is produced and the costs of extraction and processing • Demand can rise and fall quickly • When demand and supply do not match, prices can fluctuate widley, this uncertanty makes the prediction of future markets very important • Exploiting deposits in regions with existing mining activity produces benefits by having access to the existing infastructure for transport and energy, equiptment supplies and trained workforce