redox conditions affect the dissolution and precipitation of iron-bearing minerals and
materials. The dissolution and precipitation of iron-bearing minerals and materials is
introduced in Chap. 5, and sodification due to seawater inundation is introduced in
Sect. 6.2.
Phyllosilicates are the major secondary minerals in soils, and the properties of
soils depend on the composition and structure of phyllosilicates. Hence, this chapter
begins with the structures of phyllosilicates and then discusses the relationship
between the structure and function of phyllosilicates. For identification of
phyllosilicates in soil, the changes in basal spacing that occur with changes in
exchangeable cations are studied. The basal spacing can be determined with XRD,
and changes in the XRD pattern with changes in exchangeable cations (Harris and
Table 3.1 Major secondary phyllosilicate minerals in soil
Secondary phyllosilicate
Chemical formula
Kaolinite
Al 4 Si 4 O 10 (OH) 8
Halloysite (1.0 nm)
Al 4 Si 4 O 10 (OH) 8 Á4H 2 O
Halloysite (0.7 nm)
Al 4 Si 4 O 10 (OH) 8
Montmorillonite
M 0.67 Si 8 (Al 3.33 Mg 0.67 )O 20 (OH) 4 ÁnH 2 O
Beidellite
M 0.67 (Si 7.33 Al 0.67 )Al 4 O 20 (OH) 4 ÁnH 2 O
Nontronite
M 0.67 (Si 7.33 Al 0.67 )Fe 4 O 20 (OH) 4 ÁnH 2 O
Vermiculite
(Mg,Ca) 0.6–0.9 (Al,Si) 8 (Mg,Fe
3+ ,Al) 6 O 20 (OH) 4 ÁnH 2 O
Illite
K 1.5–1.0 (Si 6.5–7.0 Al 1.5–1.0 ) Al 4 O 20 (OH) 4
Mg chlorite
Mg 4 Al 2 (OH) 12 (Si 6 Al 2 )Mg 6 O 20 (OH) 4
M: Exchangeable cation
Table 3.2 Oxides,
hydroxides, and other related
inorganic constituents in soil
Chemical formula
Brucite
Mg(OH) 2
Gibbsite
Al(OH) 3
Hematite
Fe 2 O 3
Goethite
α-FeOOH
Lepidocrosite
γ-FeOOH
Ferrihydrite
Fe 5 O 7 (OH)Á4H 2 O
Siderite
FeCO 3
Lithiophorite
(Al, Li)MnO 2 (OH) 2
Birnesite
(Na, Ca)Mn 7 O 14 Á2.8H 2 O
Apatite
Ca 5 (PO 4 ) 3 (F, Cl, OH)ÁH 2 O
Brushite
CaHPO 4 Á2H 2 O
Struvite
MgNH 4 PO 4 Á6H 2 O
NH 4 -taranakite
Al 5 (NH 4 ) 3 H 6 (PO 4 ) 8 Á18H 2 O
Vivianite
Fe 3 (PO 4 ) 2 Á8H 2 O
Natrojarosite
NaFe 3 (OH) 6 (SO 4 ) 2
Gypsum
CaSO 4 Á2H 2 O
Calcite
CaCO 3
Dolomite
CaMg(CO 3 ) 2
38
3 Secondary Minerals
materials. The dissolution and precipitation of iron-bearing minerals and materials is
introduced in Chap. 5, and sodification due to seawater inundation is introduced in
Sect. 6.2.
Phyllosilicates are the major secondary minerals in soils, and the properties of
soils depend on the composition and structure of phyllosilicates. Hence, this chapter
begins with the structures of phyllosilicates and then discusses the relationship
between the structure and function of phyllosilicates. For identification of
phyllosilicates in soil, the changes in basal spacing that occur with changes in
exchangeable cations are studied. The basal spacing can be determined with XRD,
and changes in the XRD pattern with changes in exchangeable cations (Harris and
Table 3.1 Major secondary phyllosilicate minerals in soil
Secondary phyllosilicate
Chemical formula
Kaolinite
Al 4 Si 4 O 10 (OH) 8
Halloysite (1.0 nm)
Al 4 Si 4 O 10 (OH) 8 Á4H 2 O
Halloysite (0.7 nm)
Al 4 Si 4 O 10 (OH) 8
Montmorillonite
M 0.67 Si 8 (Al 3.33 Mg 0.67 )O 20 (OH) 4 ÁnH 2 O
Beidellite
M 0.67 (Si 7.33 Al 0.67 )Al 4 O 20 (OH) 4 ÁnH 2 O
Nontronite
M 0.67 (Si 7.33 Al 0.67 )Fe 4 O 20 (OH) 4 ÁnH 2 O
Vermiculite
(Mg,Ca) 0.6–0.9 (Al,Si) 8 (Mg,Fe
3+ ,Al) 6 O 20 (OH) 4 ÁnH 2 O
Illite
K 1.5–1.0 (Si 6.5–7.0 Al 1.5–1.0 ) Al 4 O 20 (OH) 4
Mg chlorite
Mg 4 Al 2 (OH) 12 (Si 6 Al 2 )Mg 6 O 20 (OH) 4
M: Exchangeable cation
Table 3.2 Oxides,
hydroxides, and other related
inorganic constituents in soil
Chemical formula
Brucite
Mg(OH) 2
Gibbsite
Al(OH) 3
Hematite
Fe 2 O 3
Goethite
α-FeOOH
Lepidocrosite
γ-FeOOH
Ferrihydrite
Fe 5 O 7 (OH)Á4H 2 O
Siderite
FeCO 3
Lithiophorite
(Al, Li)MnO 2 (OH) 2
Birnesite
(Na, Ca)Mn 7 O 14 Á2.8H 2 O
Apatite
Ca 5 (PO 4 ) 3 (F, Cl, OH)ÁH 2 O
Brushite
CaHPO 4 Á2H 2 O
Struvite
MgNH 4 PO 4 Á6H 2 O
NH 4 -taranakite
Al 5 (NH 4 ) 3 H 6 (PO 4 ) 8 Á18H 2 O
Vivianite
Fe 3 (PO 4 ) 2 Á8H 2 O
Natrojarosite
NaFe 3 (OH) 6 (SO 4 ) 2
Gypsum
CaSO 4 Á2H 2 O
Calcite
CaCO 3
Dolomite
CaMg(CO 3 ) 2
38
3 Secondary Minerals