Geology Reference
In-Depth Information
B.1.7 The chlorite group
The chlorites are a group of phyllosilicate minerals. Chlorites can be described
by the following four end members based on their chemistry via substitution of
Mg, Fe, Ni and Mn in the silicate lattice: clinochlore (Mg
5
Al)(AlSi
3
)O
10
(OH)
8
,
chamosite (Fe
5
Al)(AlSi
3
)O
10
(OH)
8
, nimite (Ni
5
Al)(AlSi
3
)O
10
(OH)
8
and pen-
nantite (Mn;Al)
6
(Si;Al)
4
O
10
(OH)
8
. The formula that represents the group is
(Mg;Fe)
3
(Si;Al)
4
O
10
(OH)
2
(Mg;Fe)
3
(OH)
6
. The main chlorite minerals, be-
sides those mentioned above, are clinochlore, ripidolite, pennantite, orthochamosite,
thuringite or penninite.
B.2 Main uses and geochemistry of the most commonly produced
minerals
The minerals of each element found in the upper continental crust are briefly des-
cribed below, with their main uses, terrestrial abundance and distribution identi-
fied. Most of the information regarding uses, principal minerals and ores has been
extracted from the following geochemical topics: Wedepohl (1969, 1971); Green-
wood and Earnshaw (1984); mineral topics and databases: Hey (1975); Duda and
Reijl (1986); Encyclopedias: Ullmann and Gerhartz (2002) and Wikipedia; Spe-
cialised Web pages: the Geochemical Earth Reference Model
16
(Staudigel et al.,
1998; Jolyon, 2007; Barthelmy, 2007) and Rare Earth Elements
17
; from commod-
ity databases: USGS (Various years); BGS (2005); technical reports: (IPPC, 2009,
2001); and papers: Gibson and Parkinson (2011); Gupta and Krishnamurthy (1992).
B.2.1 Aluminium
Aluminium is the most abundant metal in the Earth's crust. It is a major con-
stituent of many common igneous minerals, including feldspars and micas. It is a
very reactive metal and thus requires a lot of energy to extract it from its ore, baux-
ite, which is composed predominately of the minerals gibbsite Al(OH)
3
, diaspore
AlO(OH) and boehmite AlO(OH). Recovery of secondary metal from scrap deliv-
ers important energy savings. Currently about 50% of its production comes from
recycled Al. Aluminium has the following properties: it is a light, malleable, duc-
tile, easily machined and strong. It has excellent corrosion resistance and durability.
Some of the many uses for aluminium can be found in transportation (automobiles,
aircraft, trucks railcars, marine vessels, etc.), packaging (cans, foil, etc.), transmis-
sion lines, machinery, mirrors, cooking utensils and water treatment.
16
http://earthref.org/GERM.
17
http : ==rareearthelements:us=the_17_elements. Accessed Jan. 2014.
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