The Lithosphere and Mining of Mineral Resources

What is the lithosphere?

The lithosphere is the solid, rocky outer layer of the Earth. It consists of the Earth's crust (the thin outermost layer) and the rigid uppermost part of the mantle below it. The lithosphere is broken into large sections called tectonic plates, which move very slowly over time.

The lithosphere is the source of all the rocks, minerals, and soil that support life, agriculture, construction, and industry on Earth.

The three main rock types

All rocks on Earth fall into one of three categories, based on how they were formed:

Rock type	How it forms	Example
Igneous	Forms when magma (molten rock underground) or lava (molten rock on the surface) cools and solidifies	Granite, basalt
Sedimentary	Forms when small particles of sediment (sand, mud, shell fragments) are compacted and cemented together over time	Sandstone, limestone, shale
Metamorphic	Forms when existing rock is changed by intense heat and/or pressure, without melting completely	Marble (from limestone), slate (from shale)

The rock cycle

Rocks are not permanent — they are continually being transformed from one type into another over long periods of geological time, in a continuous loop called the rock cycle:

Magma/lava cools and solidifies → forms igneous rock.
Weathering and erosion break igneous (or any) rock down into sediment (small particles).
Compaction and cementation of sediment over time → forms sedimentary rock.
Heat and pressure (e.g. deep underground, or near tectonic activity) transform existing rock without fully melting it → forms metamorphic rock.
If any rock is heated enough to fully melt, it becomes magma again, and the cycle repeats.

Key idea: The rock cycle has no fixed starting or ending point — any rock type can eventually be transformed into any other rock type, given enough time, heat, pressure, weathering or melting.

South Africa's mineral wealth

South Africa is one of the world's richest countries in mineral resources, and mining has played a central role in its economic history and development.

Mineral	Significance
Gold	South Africa was historically the world's largest gold producer, especially from the Witwatersrand Basin (Johannesburg area)
Diamonds	Major deposits found near Kimberley and along the West Coast; South Africa remains a significant global producer
Platinum group metals	South Africa holds the majority of the world's known platinum reserves, mainly in the Bushveld Complex
Coal	Abundant in Mpumalanga; used mainly to generate electricity and for export

How mining works

Mining is the process of extracting valuable minerals or other geological materials from the Earth. There are two broad extraction methods:

Surface (open-pit) mining: Used when the mineral deposit is close to the surface. Layers of soil and rock are removed to expose and extract the resource. Generally cheaper and safer, but disturbs a larger surface area.
Underground mining: Used when the mineral deposit lies deep below the surface. Shafts and tunnels are dug to reach and extract the resource. More expensive and higher risk for workers, but disturbs less surface area. Many of South Africa's deep gold mines are among the deepest in the world.

Economic importance and impacts of mining

Mining brings both significant benefits and significant costs, which need to be weighed carefully.

Economic benefits

Creates hundreds of thousands of jobs
Major contributor to South Africa's GDP and export earnings
Supports related industries (transport, equipment, processing)
Provides raw materials for construction, technology, and jewellery

Environmental & social impacts

Disturbs and can permanently alter land and ecosystems
Acid mine drainage: water reacting with exposed sulphide minerals becomes acidic and can pollute rivers and groundwater — a serious issue in parts of South Africa (e.g. the Witwatersrand)
Dust and air quality impacts near mining areas
Risk to worker health and safety, particularly in underground mining

Rehabilitation: Mining companies are increasingly required to rehabilitate mined land after operations end — refilling pits, treating polluted water, and replanting vegetation — to reduce long-term environmental damage while still allowing the economic benefits of mining to be realised.

Answer the following questions in your exercise book. Use diagrams where they help explain your answer.

Question 1 · (2 marks)

Define the term "lithosphere" and name the two parts of the Earth it consists of.

Question 2 · (4 marks)

Draw a labelled diagram of the rock cycle showing all three rock types and the processes that convert one into another.

Question 3 · (3 marks)

Name THREE minerals that South Africa is a major global producer of, and for each, name a region of South Africa where it is mined.

Question 4 · (3 marks)

Distinguish between surface (open-pit) mining and underground mining. Give ONE advantage and ONE disadvantage of each.

Question 5 · (4 marks)

Discuss the economic importance of mining in South Africa, as well as TWO environmental or social impacts it can have. In your answer, refer to acid mine drainage and rehabilitation.

Question 6 · (6 marks)

South Africa's gold production has changed dramatically over the decades, partly because shallow deposits have been mined out, forcing mines deeper underground:

Year	1970	1990	2010	2020
Approx. gold production (tonnes/year)	1 000	605	190	90

(a) Calculate the percentage decrease in gold production from 1970 to 2020. Show your working. (2 marks)
(b) Using what you know about surface versus underground mining and the costs involved, suggest ONE reason why production has declined so much even though South Africa still has large gold reserves remaining underground. (2 marks)
(c) Describe ONE environmental advantage and ONE economic disadvantage of mines becoming progressively deeper over time. (2 marks)

The Lithosphere and Mining of Mineral Resources

What is the lithosphere?

The three main rock types

The rock cycle

South Africa's mineral wealth

How mining works

Economic importance and impacts of mining

Economic benefits

Environmental & social impacts

The Rock Cycle