,Chapter 1
Rocks and minerals and their exploitation
Learning outcomes
By the end of this chapter, you will be able to:
■ describe, with examples, the characteristics of igneous, sedimentary and metamorphic rocks
■ explain the formation of igneous, sedimentary and metamorphic rocks
■ explain the rock cycle
■ describe surface and subsurface mining
■ describe the reasons for extracting rocks and minerals
■ describe the impact of rock and mineral extraction on the environment and human populations
■ discuss methods of landscape restoration after rock and mineral extraction
■ explain the terms sustainable resource and sustainable development
■ discuss how rocks and minerals can be used sustainably.
, Cambridge IGCSE and O Level Environmental Management
The third rock from the Sun with oil. In 1956, the originator of the peak mineral idea,
M. K. Hubbert, predicted that the peak oil date for the
The Earth is a rocky planet, compared with, for example USA would be 1970. This did not happen, and in fact the
Jupiter, which is a gas giant. This means that the Earth production of oil in the USA is still rising today. However,
is made from rocks and metal ores. The Earth weighs it is true that the resources of all these commodities, such
5 973 600 000 000 000 000 000 000 kg (5.97 × 1026 kg) and has as coal, oil and phosphorus (current estimated peak date
a density of 5.2 g cm–3, which makes it the densest planet in 2030), copper (current estimated peak date 2040) and
the solar system. This is mainly because the core consists uranium (current estimated peak date 2030s), are finite.
of iron surrounded by a mantle of rock. However, it is It is therefore important that we limit the use of these
only the very outside part of the Earth, above the mantle, resources, and reuse and recycle them whenever we can.
that humans can use. The material that makes up this
region is what we call rocks and minerals. Although this
represents a vast amount of material, the quantity of it, like
everything else, is limited. What is more, extraction and
use can cause environmental and other problems. We are
in danger of using up the available sources of many rocks,
the most well known of which is probably coal.
Peak mineral is a concept that provides a date after which
there will only be less extraction of a mineral. Peak coal, for
example, is the date at which it is calculated that the most
coal is being extracted, after which it will decline. Because
we do not know exactly how much coal exists, estimates
of peak coal vary. Some say it is 200 years away, others
2 say it could be soon, maybe 2020. This unpredictability Figure 1.0 A giant bucket wheel excavator in use in an
because of future unknowns is illustrated by the situation open-pit mine.
1.1 Formation of rocks Igneous rocks
When molten rock from the crust and upper mantle cools,
The planet Earth was formed about 4.5 billion years ago.
igneous rocks are formed. The molten rock is called
The force of gravity pulled the heavier elements together
magma when it is still below the surface and lava when it
first, forming the core. The lighter elements then formed
reaches the surface.
the Earth’s crust about 3–4 billion years ago. The mantle
developed as a layer between the dense core and the light Magma is found in the outer mantle; it is hot, liquid rock
crust. This structure still exists today (Figure 1.1). that is under pressure from the rocks above it. When it
crust continental crust
0–100 km
mantle
oceanic crust
outer core
2900 km
inner core 5100 km
6370 km
mantle
Figure 1.1 The structure of the Earth.
Rocks and minerals and their exploitation
Learning outcomes
By the end of this chapter, you will be able to:
■ describe, with examples, the characteristics of igneous, sedimentary and metamorphic rocks
■ explain the formation of igneous, sedimentary and metamorphic rocks
■ explain the rock cycle
■ describe surface and subsurface mining
■ describe the reasons for extracting rocks and minerals
■ describe the impact of rock and mineral extraction on the environment and human populations
■ discuss methods of landscape restoration after rock and mineral extraction
■ explain the terms sustainable resource and sustainable development
■ discuss how rocks and minerals can be used sustainably.
, Cambridge IGCSE and O Level Environmental Management
The third rock from the Sun with oil. In 1956, the originator of the peak mineral idea,
M. K. Hubbert, predicted that the peak oil date for the
The Earth is a rocky planet, compared with, for example USA would be 1970. This did not happen, and in fact the
Jupiter, which is a gas giant. This means that the Earth production of oil in the USA is still rising today. However,
is made from rocks and metal ores. The Earth weighs it is true that the resources of all these commodities, such
5 973 600 000 000 000 000 000 000 kg (5.97 × 1026 kg) and has as coal, oil and phosphorus (current estimated peak date
a density of 5.2 g cm–3, which makes it the densest planet in 2030), copper (current estimated peak date 2040) and
the solar system. This is mainly because the core consists uranium (current estimated peak date 2030s), are finite.
of iron surrounded by a mantle of rock. However, it is It is therefore important that we limit the use of these
only the very outside part of the Earth, above the mantle, resources, and reuse and recycle them whenever we can.
that humans can use. The material that makes up this
region is what we call rocks and minerals. Although this
represents a vast amount of material, the quantity of it, like
everything else, is limited. What is more, extraction and
use can cause environmental and other problems. We are
in danger of using up the available sources of many rocks,
the most well known of which is probably coal.
Peak mineral is a concept that provides a date after which
there will only be less extraction of a mineral. Peak coal, for
example, is the date at which it is calculated that the most
coal is being extracted, after which it will decline. Because
we do not know exactly how much coal exists, estimates
of peak coal vary. Some say it is 200 years away, others
2 say it could be soon, maybe 2020. This unpredictability Figure 1.0 A giant bucket wheel excavator in use in an
because of future unknowns is illustrated by the situation open-pit mine.
1.1 Formation of rocks Igneous rocks
When molten rock from the crust and upper mantle cools,
The planet Earth was formed about 4.5 billion years ago.
igneous rocks are formed. The molten rock is called
The force of gravity pulled the heavier elements together
magma when it is still below the surface and lava when it
first, forming the core. The lighter elements then formed
reaches the surface.
the Earth’s crust about 3–4 billion years ago. The mantle
developed as a layer between the dense core and the light Magma is found in the outer mantle; it is hot, liquid rock
crust. This structure still exists today (Figure 1.1). that is under pressure from the rocks above it. When it
crust continental crust
0–100 km
mantle
oceanic crust
outer core
2900 km
inner core 5100 km
6370 km
mantle
Figure 1.1 The structure of the Earth.
