rocks, minerals and their eploitation

define igneous rocks

they are formed by the cooling or crystallization of lava or magma during the volcanic eruption

types of igneous rocks

extrusive: rocks cool down quickly therefore forming smaller crystals. eg: basalt

intrusive: rocks cool down slowly, so they form larger crystals. eg: granite

define sedimentary rocks

are formed by the weathering of existing rocks on earth’s surface.

eg: limestone, sandstone and shale

describe process of sedimentary rock formation

when igneous rocks get exposed to elements like wind and air, they erode to form sediments. These sediments undergo high heat and pressure, so they are compacted and cemented into sedimentary rocks.

define metamorphic rocks

when pre-existing rocks get exposed to heat and pressure under the surface of the earth, they harden to form metamorphic rocks.

eg: marble and slate

what is a property all three rocks share?

they all melt to form magma

define prospecting

 process of finding rocks by looking at the surface of the rock.

define remote sensing

method of finding rocks by taking aerial photography of the area using drones that have a camera attached to it. 

define surface/open-cast mining

method of extraction where the rock is lying closer to the surface.

describe process of surface mining

clear vegetation/overburden in the area/ore

use explosives to loosen the rock and expose the ore

use a digger to remove loose rock

rock/minerals are loaded into the truck and transported to factories for purification.

define sub-surface mining

method of extraction that involves almost no removal of overburden and extraction is done through a tunnel which is dug.

describe the process of sub-surface mining

sink a vertical shaft down to the mineral bearing layer

make a horizontal tunnel following the mineral layer

extract minerals by digging via miners or machines

bring loose rock to the surface ad pile it up in waste heaps

transport to market by railway or road

advantages of Surface Mining

more efficient

faster extraction

cheaper

less dangerous

disadvantages of Surface Mining

removal of vegetation has negative externalities for the environment

habitats destroyed by explosives and deforestation

noise pollution

air pollution from dust particles

advantages of sub-surface mining

minimized environmental impact as no overburden is removed

more profitable

no loss in habitat

disadvantages of sub-surface mining

mining deep into earth causes decrease in water quality

miners can get trapped and die during bad weather

exposure to toxic gases can pose health risks.

e factors that affect the decision to extract rocks and minerals

exploration + extraction: machinery and explosives are expensive

geology: thick layers and unbroken horizontal beds = easier to use machines

accessibility: (proximity)

environmental impact

supply and demand:

describe economic impact of rock and mineral extraction

job creation

tax revenue earned from this can be reinvested to improve transport services and infrastructure

supply>demand = loss

high costs (machinery and explosives)

+output = better GDP so better economy

describe environmental impact of rock and mineral extraction

loss of habitat and biodiversity

air pollution (fuel CO2)

noise pollution

visual pollution: removal of overburden, waste heaps

water pollution: surface runoff, chemical leaching from waste heaps

soil pollution: less vegetation so soil erosion

how to manage the impact of rock and mineral extraction

safe disposal of mining waste

land restoration

bioremediation: (microorganisms)

making lakes and natural reserves (biodiversity)

afforestation: on barren land

re-forestation: on reforested land

define sustainable resource

a resource that can be continually replenished

define sustainable development

development that meets the needs of the present, without compromising the ability for the future generations to meet their own needs.

strategies to sustainably use rocks and minerals

increasing efficiency:

1) improvements in machinery performance

2) double processing waste to get all minerals and reduce pollution

recycling them: less energy and waste than processing ores

legislation: laws to make manufacturers reuse and recycle