Africa´s Natural Resources in a Global Context...

The IMRE Journal Volume 8 (2) 2014 2014. TU Bergakademie Freiberg http://www.wiwi.tu-freiberg.de/~urm/imre/ej

Africa´s Natural Resources in a Global Context

Leopold WEBER

Former head of the “Minerals Policy Department” of the Austrian Federal Ministry for Economy, Family and Youth, Vienna Correspondence: [email protected]:

Revised: 02.12.2014 Online Publication Date: 18.12.2014

Abstract

The article deals with the trends of the global mining production of the

past three decades and Africa’s contribution in particular. The author

discusses, why on the one hand side some important minerals (e.g. copper)

or deposit types (e.g. porphyries and skarns) are scarcely developed in

Africa. On the other side Africa is doubtless the continent with the most

important resources of precious metals.

Due to the favorable geology there are numerous prospective exploration

targets. However, in some cases the exploration of those targets or their

development to mines are hindered by the remoteness of the occurrences,

missing infrastructure and political instability of some countries. In any

case, Africa is a continent with a bright future as a global minerals

supplier.

Keywords: World Mining Production; Africa, Copper, Gold, Resources

Introduction

From a global sight 86.5 % of the total minerals production refer to fossil

energy fuels. As those minerals get combusted, they can never be reused or

recycled. According to United Nations (1987) (“Brundtland Report”)

sustainable development should meet the demand of the present without

compromising the ability of the future generations to meet their own

needs. With respect to the above mentioned definition sustainable

development can hardly be achieved.

Since the beginning of the 21th

century China changed from a minerals

supplier to a minerals consumer, resulting in a worldwide boost of mining

production. The mining output rose significantly in Asia. Contrary to Asia,

mining in Africa developed quite different.

Africa’s geology differs significantly from other continents. Most of the

typical African mineralisations (iron ores, chromites, precious metals) are

linked to the oldest cratogenic and orogenetic events of the earth’s history.

Young plate tectonic related events, famous for porphyry-like

mineralisations containing Cu or Mo) are missing or are less developed.

Furthermore huge parts of Africa are covered with deserts. Missing or poor

infrastructure are further hindrances.

Africa’s Natural Resources in a Global Context WEBER, L.

The IMRE Journal

1 Global Trends

Sectoral trends Since 2003 world mining production shows a

remarkable increase. In 2012 16.8 billion t of minerals

(without bauxite and construction minerals) have been

mined. Compared to 2003 this is an increase of more

than 37%, never observed in the previous years. From

the economic aspect, energy fuels contribute by far with

86.5 % of the total minerals production (Figure 1.1).

Figure 1.1: Global mining production by groups of minerals

(without bauxite and construction materials) in Mio t

Regional Trends

Asia is the by far most important mining continent,

contributing more than 58 % of the world mining

production. With respect to the development of the past

three decades, most of the mining activities take place

in Asian countries (Figgure 1.2). It is not to be overseen

that the huge increase of minerals production within the

past decade is concentrated to Asian countries.

Compared with other continents, Africa’s minerals

output is surprisingly low. Europe’s minerals

production is dominated by Germany’s lignite

production. Both lignite and the production of the

remaining minerals in Europe is shrinking.

Figure 1.2: Global mining production by continents


On the one hand, the most important minerals

production results from mining activities in developing

countries. On the other hand, the minerals output from

developed countries or transition countries is more or

less stagnant. The minerals output of less developed

countries is nearly insignificant. (Figure 1.3).

Figgure 1.3: Global mining production by developing status


Geopolitical Trends

For an undisturbed minerals supply of the market,

political stability of producer countries is of extreme

importance. However, nearly two thirds of the total

world minerals output arise from political instable or

even extremely instable countries (Figgure 1.4). The

political stability has been indexed by the World Bank

(Kaufmann et al., 2010).


The IMRE Journal

Figure 4: Global mining production by political stability


Political stability estimates: World Bank

2 Africa’s contribution to world mining

In the last three decades Africa’s minerals production

developed differently to Asia as the trend setting

continent. The broken trend in minerals production had

its reasons in Northern Africa. Amongst the worldwide

financial crisis in 2009 the Libya conflict influenced the

hydrocarbon production dramatically. Contrary to this,

the minerals production in Sub-Saharan Africa

remained more or less unaffected. Compared with Asia

the increase of minerals production was quite moderate

(Figure 2.1).

Figure 2.1: Africa’s mining production by world regions (acc.

IASSA); SSA: Sub-Saharan Africa; NA: Northern Africa;


Iron and steel alloying metals

With regard to the group of iron ore and steel alloys,

Africa is the top producing continent for tantalum and

cobalt, both produced in Sub-Saharan countries

(Rwanda, DR Congo).The same is true for chromite,

vanadium and titanium, which are primarely mined in

the ultramafic Bushveld and Great Dyke complexes in

South Africa and Zimbabwe. Northern Africa’s

contribution is marginal (Table 2.1).

Table 2.1: Africa’s share of 2012 global production in %; Iron and

steel alloying metals; NAF: Northern Africa; SSA: Sub-Saharan

Africa

Non ferrous metals

Surprisingly, Africa’s part of the world non ferrous

metal production is extremely poor. With exception of

Arsenic, a byproduct from polymetallic mining in

Northern Africa, copper, lead and zinc are mostly

mined in Sub-Saharan Africa (Table 2.2).

Table 2.2: Africa’s share of 2012 global production in %; Non

ferrous metals; NAF: Northern Africa; SSA: Sub-Saharan Africa

Industrial Minerals

Diamonds are important commodities, both mined in

Sub-Saharan Africa. The same is true for vermiculite.

On the other side both phosphates and barytes are

primarely produced in Northern Africa (Table 2.3).


The IMRE Journal

Table 2.3: Africa’s share of 2012 global production in %; Non

ferrous metals; NAF: Northern Africa; SSA: Sub-Saharan Africa

Precious Metals

The most important PGE metal resources are located in

the geologically unique ultrabasic Bushveld and Great

Dyke complexes in South Africa and Zimbabwe. Gold

is primarily concentrated in Sub-Saharan African

countries (e.g. South Africa, Ghana, Tanzania; Table

2.4).

Table 2.4: Africa’s share of 2012 global production in %; Precious

metals; NAF: Northern Africa; SSA: Sub-Saharan Africa

Energy fuels

Compared with the other continents, Africa is poor in

energy fuels. Hydrocarbons are produced both in

Northern and Sub-Saharan Africa, whereas coal is

produced in Sub-Sahara Africa only (Table 2.5).

Table 2.5: Africa’s share of 2012 global production in %; Energy

fuels; NAF: Northern Africa; SSA: Sub-Saharan Africa

3 Is Africa an underexplored continent?

Is Africa’s geology so specific, that some minerals are

“abundant” and others missing? Are parts of Africa

unexplored?

Undoubtedly the geology of Africa is quite different to

Europe, North- or Latin America and primarely

controlled by Archaean and Proterocoic complexes.

Hercynian or alpine tectonic orogens are of minor

importance.

Paleoarchaean: Formation of early Archaean cratonic

cores (Kapvaal, Tokwe).

Mesoarchaean: Accretionary growth of the Kapvaal-,

Zimbabwe-, Congo- and Tanzania cratons and

the Man- and Reguibat shield.

Neoarchaean: Stabilisation of the Kapvaal-, Zimbabwe-

, Congo- and Tanzania cratons and the Man- and

Reguibat shields, merging of the Kapvaal- and

Zimbabwe cratons as the South African Craton

Eburnian Orogeny (2,2 – 1,8 Ma): Growth of the West

African craton along an active accretionary

margin (Birrimian): merging of the Congo- and

Tanzania Craton. Passive margin developement

and orogenesis along the west margin of Central

and Southern Africa cratons.


The IMRE Journal

Figure 3.1: Simplified geologic map of Africa:

Source: Begg, G.C. et al. (2009)

Kibaran Orogeny: (1,4 – 0,85 Ma): Merging of South-

and Central African plutons as part of the

Rodinia supercontinent

Pan African Orogeny (0,85 – 0,5 Ma): Merging of all

cratonic fragments to form the Gondwana

supercontinent to which Africa is central

Hercynian Orogeny (0,45 – 0,25 Ma): Limited collision

and tectonic activity along the NW and S

margins of the African plate

Alpine Orogeny (0,12 – 0 Ma): Subduction of the

African plate under Eurasia, forming of the

Atlas Mountains (Figure 3.1)

The case of copper

Table 3.1: Distribution of the

global copper resources

(*Asia excl. China); Data

coverage: (measured and

indicated) resources figures

according JORC / SAMREC

codes of 307 mine sites;

covering appr. 95% of world

mining production 2013;

Source: company reports

Remark: The resource figures in this paper refer to

measured and indicated resources and do not include

inferred resources. Furthermore, the resource figures

reflect the present day situation and not initial

resources of the operated deposits.

Figures in Table 3.1 show clearly that Africa is not

amongst the continents with huge copper resources.

Most of the copper resources are linked to porphyry or

skarn type deposits (Figure 3.1), which are mainly

developed in geologically young andinotype orogens

(Andes in Latinamerica, Northamerican Cordillieres,

Circumpacific orogens).

Porphyry copper deposits are concentrated along

convergent tectonic margins, where oceanic tectonic

plates become subducted under the continental plates.

Under high temperatures, parts of the subducted plates

are melting. The molten rocks form magma chambers,

rising up near below surface. During cooling of the

magma vapor pressure is raising. A higher vapor

pressure than the lithostatic pressure causes hydraulic

fracturing and (retrograde) boiling of hydrothermal

fluids. Under those conditions Cu-(Mo) bearing

minerals form stockwork like mineralisations, known as

“Porphyry copper ores”. Magmas, getting in contact

with carbonatic rocks, generate irregular shaped Skarn-

deposits. Contrary to the North and Latin American continent.

Africa is not affected by those specific tectonic

movements, so that porphyries did not form.

The multistage “Sediment hosted copper

mineralisations” the Central African (Zambian) Copper

belt are linked to the Neoproterocoic Roan Series,

overlying a Paleoproterocoic granitic basement. Most


The IMRE Journal

likely the sediment cover is the product of the granitic

basement, containing polymetallic mineralisations as a

primary source of the sediment hosted (secondary) Cu-

Co mineralisations (Theron, 2013). As the local setting

is unique, it is unlikely to find similar mineralisations in

size and grade elsewhere.

Contrary to the Neoproterocoic metallogenesis of the

Central African Copper belt, the “European sediment

hosted copper mineralisations” are of Late Permian Age

and do not contain Cobalt. The “Kupferschiefer”

mineralisations are linked to a narrow seam of black

shales, overlying Permian sandstones (Weißliegendes,

Rotliegendes), as the prime rock of the metals. Those

mineralisations are only developed in Europe (e.g.

Germany, Poland), and as a matter of fact missing in

Africa.

Table 3.1: Comparison of the global and African copper resources

by type of deposits. Abbr.: IOCG: Iron Oxide Copper Gold

deposits; SEDEX: Sedimentary Exhalative deposits; VMS:

Volcanogenic Massive Sulfides; Dissem.: disseminated

mineralisations

From a worldwide view the Paleogene is the most

important period for copper mineralisations

(Porphyries, Skarns). In Africa those mineralisations are

not developed. The most important African copper

mineralisations formed in the Neoproterocoic (Table

3.2).

Table 3.2: Comparison of the global and African copper

resources by age of the mineralisation

Statistically the average size of a copper deposit is 522

Mio t of ore with copper grades of appr. 1%.

Figure 3.2: Histogram of the metal content of all types of Cu

resources

The histogram (Figure 3.2) shows the distribution of the

metal contents of all types of copper deposits. An

“average” copper deposit contains 3,157 Mio t of Cu;

“large” deposits (m+1) >9,721 Mio t, and “super

large” deposits (m+2) >16,284 Mio t of Cu.

Without any doubt, porphyry and skarn type

mineralisations are the largest by size, but low in grade.

Porphyry and skarn type mineralisations are important

carriers of gold (26,8 %) and molybdenum too.


The IMRE Journal

Table 3.3: Comparison of the global and African copper resources

by average size, grade and copper content. Abbr.: IOCG: Iron

Oxide Copper Gold deposits; SEDEX: Sedimentary Exhalative

deposits; VMS: Volcanogenic Massive Sulfides; Dissem.:

disseminated mineralisations

On the other side, massive sulfide deposits are lower in

size, but higher in copper grade. Additionally, those

mineralisations contain lead and zinc.

Figure 3.3: Size and grade of global copper resources by type of

mineralisations

Figure 3.4: Size and grade of African copper resources by type of

mineralisations

In Africa, mineralisations of the porphyry-skarn type

are missing (see Fig. 3.4). In contrast, the sediment

hosted copper-cobalt type mineralisations are mainly

developed in Africa only (DR Congo; Sambia). Most of

those mineralisations are characterized by copper

grades higher than average. Some of those are amongst

the largest deposits worldwide, although not as large as

porphyry type mineralisations. The remaining types of

African copper deposits play a minor role only.

The case of gold

Table 3.4: Distribution of the

global gold resources (*Asia

excl. China); Data coverage:

(measured indicated)

resources figures according

JORC / SAMREC codes of

358 mine sites; covering

appr. 64% of world mining

production 2013; Source:

company reports

Africa is by far the most important continent for gold

resources (Table 3.4). The most important types of gold

deposits are greenstone hosted mineralisations and

oligomictic conglomerates. Porphyry copper and Skarn

mineralisations are known for low gold concentrations.

However those mineralisations contain more than 26%

of the world gold resources. Gold is extracted as an

economically important byproduct, but not as a primary

material.

“Greenstone hosted mineralisations” occur in

greenstone belts, which have been intruded by younger

granitic complexes. The veinlike quartz-carbonate Au-


The IMRE Journal

mineralisations, which are situated in shearzones are the

result of hydrothermal metalliferous solutions. Some of

the greenstone hosted gold mineralization are of

Archean age and belong to the oldest mineralisations

known. Greenstone hosted mineralisations occur in

Sub-Saharan Africa (e.g. South Africa, Tanzania).

The erosion of greenstone hosted gold mineralisations

under anoxic aquatic and atmospheric conditions led to

long-distances transport and resedimentation as Au-

bearing “oligomictic conglomerates” in shallow aquatic

environments (“Paleoplacers”). Those mineralisations

formed in the South-African Witwatersrand basin

(Paleoproterocoic) and Tarkwa (Ghana, Archean).

The genesis of IOCG (Iron Oxide Copper Gold)

deposits is still under discussion. However, there is

strong evidence that “Banded Iron Formations” have

been overprinted hydrothermally.

“Carlin Type mineralisations” are hydrothermal

concentrations in limestones and sandstones, closely

linked to Mesocoic, Paleogene and Neogene magmatic

events. Those mineralisations are wide spread in the US

(Nevada). Table 3.5: Comparison of the global and African gold resources

by type of deposits; Abbr.: IOCG: Iron Oxide Copper Gold

deposits; Dissem.: disseminated mineralisations

Table 3.6: Comparison of the global and African gold resources

by age of deposits

Table 3.7: Comparison of the global and African gold resources

by average size, grade and copper content. Abbr.: IOCG: Iron

Oxide Copper Gold deposits; Massive Sulfides;Dissem.:

disseminated mineralisations

Fig. 3.5: Histogram of the metal content of all types of Au

resources

Statistically the average size of a gold deposit is 197 t

Mio t of ore and grades of appr. 3,2 g/t.


The IMRE Journal

The histogram in Figure 3.5 shows the distribution of

the metal contents of all types of gold deposits. An

“average” gold deposit contains 163,5 t of Au; “large”

deposits (m+1) >700 t, and “super large” deposits

(m+2 ) >1237 t of Au.

Figure 3.6: Size and grade of global gold resources by type of

mineralisations;

Figure 3.7: Size and grade of African gold resources by type of

mineralisations; Abbreviations to Fig. 3.6 and 3.7: Ortho:

orthomagmatic mineralization, green: greenstone hosted

mineralisations, Por, Sk: Porphyries and skarns, diss.:

disseminated mineralisations; IOCG: Iron Oxide Copper Gold

mineralisations; MS.: Massive sulfides; Congl.: Conglomerates

4 Quo vadis, Africa ?

Africas gold output is continuously sinking. Being the

top producing country in the 1980-ies it lost its leading

position in 2007 (Figure 4.1). The main reasons

amongst others are the high geotechnical problems and

high production costs due to mining in 3000 m below

surface. In contrast, the production costs of surface near

Carlin type mineralisations with similar metal grades in

the US State of Nevada by open pit mining are much

lower.

Figure 4.1: Production trends of the principal gold producer

countries; vertical axis: gold production in metr. t.

5 Conclusion

Minerals distribution and concentration on the African

continent is heavily depending on its unique geologic

and tectonic history. As a conglomerate of stable

microcontinents, welded together in the Archean and

the Proterocoic, and less important „young“ tectonic

regions, some types of economic important types of

mineral deposits (e.g. base metals) are missing or less

developed.

Greenstone belts, formed during Archaean and

proterocoic orogene cycles host numerous gold bearing

shearzone mineralisations (primary gold

mineralisations). Due to the anoxic atmospheric and

aquatic environment the Archean and the Proterocoic

was a favorable period for the concentration secondary

precious metal deposits. Both greenstone belts and

sediments are well developed in Africa.

However, there are numerous prospective areas for

mineral deposits both in the Archean crust and orogenic

belts, but huge parts of Africa are overlain by deserts.

Remote locations of some deposits and poor infrastructure constitute problems to develop deposits to

economic mines. Nevertheless, Africa‘s (specific) minerals potential is of

crucial importance for the future supply with mineral

commodities.

References

Begg, G.C., Griffin, W.L. et al. (2009): The lithospheric

architecture of Africa: Seismic tomography,

mantle petrology, and tectonic evolution.-

Geosphere 5, 23 – 50, Boulder.

0

100

200

300

400

500

600

700

800

900

1000

1984

1986

1988

1990

1992

1994

1996

1998

2000

2002

2004

2006

2008

2010

2012

USA South Africa Australia China


The IMRE Journal

Reichl, S., Schatz, M., Zsak, G. (2014): World Mining

Data 2014.- 251 p., Federal Ministry of Science,

Research and Economy, Vienna.

Kaufmann, D., Kraay, A. & Mastruzzi, M. (2010): The

worldwide Governance Indicators: Methodology

and Analytical Issues.- World Bank Policy Research Paper No. 5430;

http://ssrn.com.abstract=1682130

THERON, S.J. (2013): The origin of the Central

African Copperbelt: in a nutshell.- The Southern

African Institute of Mining and Metallurgy;

Base Metals Conference 2013; 21 – 36.

United Nations (1987); Report of the World

Commission on Environment and Development: Our

Common Future.- 42nd session; („Brundtland report“)

(1987)

http://ssrn.com.abstract=1682130/

Africa´s Natural Resources in a Global Context...

Documents

Transcript of Africa´s Natural Resources in a Global Context...