Geology Reference
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until depletion, if production remains as in 2008 and should no more resources be
found, is also shown in Table 11.19. The total minimum exergy B t is the sum of
the chemical B ch and concentration B c components, calculated with Eq. (9.29) 13
and Eq. (9.30).
In the authors' opinion, reserves, as opposed to resources, are not good indicators
for the assessment of the Earth's mineral endowment. This is because as stated
by Highley et al. (2004), total world reserves of most mineral commodities are
larger now than at any time in the past due to greater and more widely available
geological information, increasingly e cient technologies and price fluctuations. Yet
the information about world resources remains relatively scarce, inaccurate and
incomplete, as can be seen in Table 11.19. Put simply, too little is known about the
Earth's crust, due to extremely high exploration costs.
Table 11.19: The exergy (B t ) of mineral reserves and world resources. Values
are expressed in ktoe
Substance
reported
by USGS
Mineral ore
Production
(2008)
Reserves
(2010)
Resources
R/P,
years
Aluminium
(Bauxite)
Gibbsite
5.86E+02
7.72E+04
2.14E+05
132
Antimony
Stibnite
4.93E+01
5.26E+02
N.A.
11
Arsenic
Arsenopyrite
1.12E+01
2.60E+02
2.34E+03
23
Barium
Barite
3.12E+01
6.59E+02
7.76E+03
21
Beryllium
Beryl
1.34E-02
N.A.
N.A.
N.A.
Bismuth
Bismuthinite
9.94E-01
4.13E+01
N.A.
42
Boron
Kernite
3.69E+02
1.44E+04
N.A.
39
Cadmium
Greenockite
3.17E+00
9.55E+01
9.71E+02
30
Cesium
Pollucite
N.A.
2.23E-01
N.A.
N.A.
Chromium
Chromite
3.47E+02
1.18E+04
4.05E+05
34
Cobalt
Linnaeite
3.14E+01
2.73E+03
6.21E+03
87
Copper
Chalcopyrite
8.94E+03
3.13E+05
1.74E+06
35
Feldspar
Orthoclase
7.30E+01
N.A.
N.A.
N.A.
Fluorspar
Fluorite
2.53E+02
9.65E+03
2.10E+04
38
Gallium
Ga in bauxite
1.96E-02
N.A.
1.77E+02
N.A.
Germanium Ge in sulfide ores
2.60E-02
N.A.
N.A.
N.A.
Gold
Native gold
1.76E-02
3.66E-01
N.A.
21
Graphite
Graphite
9.46E+02
6.00E+04
6.76E+05
63
Gypsum
Gypsum
8.78E+02
N.A.
N.A.
N.A.
Hafnium
Hf in Zn ores
3.71E+01
8.00E+04
N.A.
2153
Helium
He in natural gas
N.A.
N.A.
N.A.
N.A.
Indium
In in Zn, Pb and
Cu sulfides
5.45E-02
1.05E+00
N.A.
19
Iodine
I in brines
5.34E-01
3.02E+02
6.85E+02
566
Iron ore
Hematite
1.17E+04
8.40E+05
4.20E+06
72
Lead
Galena
3.38E+02
6.96E+03
1.32E+05
21
Limestone
Calcite
2.86E+03
N.A.
N.A.
N.A.
Continued on next page :::
13 The chemical exergy of the elements considered is that obtained with the R.E. update explained
in Table 9.1.
 
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