**1. Introduction**

Historically, clay mineral has long benefitted human life and civilization. Being an integral part of earth, its history is older than the creation of man. The divine script of Holy Quran confirmed that man was created using clay. This indicates that clay mineral was present before

© 2016 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. © 2018 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

the human life began on earth. The ancient Greek philosophy and culture consider clay an important component of life. Currently, the twenty-first century is in the process of appreciating the even growing number of clay applications in material science.

In times when technology was not at the core of human civilization, clay mineral was used as an important form of material to form a variety of products. Its softness, plasticity, porosity, tangibility, pliability, and climatic adaptability, all at affordable cost, were viable characteristics to recognize its usefulness, and introduced several products.

Today, when nanotechnology is the hallmark of scientific world, the contribution of clay mineral is significantly visible as highly useful fillers or additives in polymers for desired effects. Nanoclays, based on montmorillonite, are currently used to modify the polymer performance.

The science of clay was introduced since prehistoric times. Ceramists used nanoparticles since antiquity [1]; however, nanotechnology is the knowingly scientific utilization of nanoparticles. The use of kaoline may be traced back to the third century BC in China. China clay, a traditional name of kaoline, is a mixture of minerals generally containing kaolinite, quartz, mica, feldspar, illite, and montmorillonite [2].

Historically, the use of clay is known in architecture, industry, and agriculture. The production of sun-dried and fired bricks for building construction still follows century-old procedures. Floor tiles, ceramics, earthenware, and pipes for drainage are examples of clay-based products used since ages. An interesting behavior of clay, in producing products, is its ability to swell and to mold in water, and retain the shape of a container when dry.

A common characteristic of clay mineral is a fine-grained natural structure in a sheet-like geometry. The sheet-structured hydrous silicates are generally called phyllosilicates [3]. The natural clay particle is smaller than 0.004 mm in diameter that may range from 0.002 to 0.001 mm for quartz, mica, feldspar, iron, and aluminum oxides [4]. Colloidal clay particles are finer and found in layered silicates (<0.001 mm in diameter).

Clay minerals may be grouped in four types, shown in **Table 1**. The group members vary mainly in the layered structure. These include the kaolinite group, the smectite group (montmorillonite group), the illite group, and the chlorite group [5].

The kaolinite group has three members including kaolinite, dickite, and nacrite; the formula for kaolinite group is Al2 Si2 O5 (OH)<sup>4</sup> .

layer; 2:1 clay mineral would contain two tetrahedral sheets and one octahedral sheet sandwiched between the two tetrahedral sheets (montmorillonite is an example of clay mineral having 2:1 sheet structure); and 2:1:1 clay minerals are composed of an octahedral sheet adjacent to a 2:1 layer [6]. The sheet structure for the layers of various clay minerals with the

**Group name Member minerals General formula Remarks**

Si2 O5

(Si, Al)<sup>4</sup>

XH2 O

**S. no Clay mineral group Layer type Layer charge** 1. Kaolinite 1:1 <0.01 2. Montmorillonite or smectite 2:1 0.5–1.2 3. Illite 2:1 1.4–2.0 4. Vermiculite 2:1 1.2–1.8 5. Chlorite 2:1:1 Variable

(Ca, Na, H) (Al, Mg, Fe, Zn)<sup>2</sup>

⋅ XH2 O

> O10(OH)<sup>2</sup> ⋅

O10(OH)<sup>2</sup>

(Si, Al)<sup>4</sup>

Al4 Si2 O10(OH)<sup>8</sup>

Fe3

O10 (OH)<sup>8</sup>

O10(OH)<sup>8</sup>

O10(OH)<sup>8</sup>

Si3

**iv.** (Ni, Mg, Fe, Al)<sup>6</sup> AlSi3

**i.** (Mg, Fe)<sup>4</sup>

**ii.** (Fe, Mg)<sup>3</sup>

AlSi3

**iii.** LiAl5

(OH)<sup>4</sup> Members are polymorphs

Montmorillonite: An Introduction to Properties and Utilization

structure.

http://dx.doi.org/10.5772/intechopen.77987

(composing of the same formula and different

"X" indicates varying level of water in mineral type.

5

"X" indicates varying level of water in mineral type.

Each member mineral has a separate formula. This group has relatively larger member minerals and sometimes considered as separate group not as part of clays.

1. Kaolinite Kaolinite, dickite, nacrite Al2

talc, vermiculite, sauconite, saponite, nontronite

3. Illite Illite (K, H)Al<sup>2</sup>

**iv.** Nimite, and so on

**ii.** Chamosite, **iii.** Cookeite,

2. Smectite Montmorillonite, pyrophyllite,

4. Chlorite **i.** Amesite,

**Table 1.** Major groups of clay minerals [5].

Natural reserves of montmorillonite are present in various parts of the world. An earliest discovery of montmorillonite was indicated in 1847 in Montmorillon in the Vienne prefecture of France. However, the use of montmorillonite for medicinal purposes may be in over 200 cultures including the ancient Egyptians, pre-Aztec Amargosians, natives of Mexico, South

The names used for montmorillonite are known in different languages, including montmorillonita (Portuguese, Catalan, and Spanish), montmorilloniet (Dutch), and montmorillonit

possible charge is shown in **Table 2** [7].

**Table 2.** Sheet structure for the layers of clay minerals [7].

**S. no**

Americans, and North Americans [8].

(German, Hungarian, Slovak) [9].

The illite group is represented by mineral illite, the only common clay type. The general formula for illite is (K, H)Al<sup>2</sup> (Si, Al)<sup>4</sup> O10(OH)<sup>2</sup> <sup>⋅</sup> XH2 O. It is an important rock-forming mineral and main component of shales. The structure of this group is similar to the montmorillonite group with silicate layers sandwiching an aluminum oxide/hydroxide layer in the same stacking sequence.

The chlorite group is relatively large. This group is not necessarily considered as part of clays; therefore, it is placed as a separate group in phyllosilicate. The members in chlorite group are mesite, chamosite, cookeite, and daphnite with varying formulas and structures. There is no general formula.

The variety of clay minerals is based on the arrangement of tetrahedral and octahedral sheets. For example, 1:1 clay mineral would have one tetrahedral and one octahedral sheet per clay


**Table 1.** Major groups of clay minerals [5].

the human life began on earth. The ancient Greek philosophy and culture consider clay an important component of life. Currently, the twenty-first century is in the process of appreciat-

In times when technology was not at the core of human civilization, clay mineral was used as an important form of material to form a variety of products. Its softness, plasticity, porosity, tangibility, pliability, and climatic adaptability, all at affordable cost, were viable characteris-

Today, when nanotechnology is the hallmark of scientific world, the contribution of clay mineral is significantly visible as highly useful fillers or additives in polymers for desired effects. Nanoclays, based on montmorillonite, are currently used to modify the polymer performance. The science of clay was introduced since prehistoric times. Ceramists used nanoparticles since antiquity [1]; however, nanotechnology is the knowingly scientific utilization of nanoparticles. The use of kaoline may be traced back to the third century BC in China. China clay, a traditional name of kaoline, is a mixture of minerals generally containing kaolinite, quartz,

Historically, the use of clay is known in architecture, industry, and agriculture. The production of sun-dried and fired bricks for building construction still follows century-old procedures. Floor tiles, ceramics, earthenware, and pipes for drainage are examples of clay-based products used since ages. An interesting behavior of clay, in producing products, is its ability

A common characteristic of clay mineral is a fine-grained natural structure in a sheet-like geometry. The sheet-structured hydrous silicates are generally called phyllosilicates [3]. The natural clay particle is smaller than 0.004 mm in diameter that may range from 0.002 to 0.001 mm for quartz, mica, feldspar, iron, and aluminum oxides [4]. Colloidal clay particles

Clay minerals may be grouped in four types, shown in **Table 1**. The group members vary mainly in the layered structure. These include the kaolinite group, the smectite group (mont-

The kaolinite group has three members including kaolinite, dickite, and nacrite; the formula

The illite group is represented by mineral illite, the only common clay type. The general for-

<sup>⋅</sup> XH2

and main component of shales. The structure of this group is similar to the montmorillonite group with silicate layers sandwiching an aluminum oxide/hydroxide layer in the same stack-

The chlorite group is relatively large. This group is not necessarily considered as part of clays; therefore, it is placed as a separate group in phyllosilicate. The members in chlorite group are mesite, chamosite, cookeite, and daphnite with varying formulas and structures. There is no

The variety of clay minerals is based on the arrangement of tetrahedral and octahedral sheets. For example, 1:1 clay mineral would have one tetrahedral and one octahedral sheet per clay

O. It is an important rock-forming mineral

O10(OH)<sup>2</sup>

to swell and to mold in water, and retain the shape of a container when dry.

are finer and found in layered silicates (<0.001 mm in diameter).

morillonite group), the illite group, and the chlorite group [5].

(Si, Al)<sup>4</sup>

Si2 O5 (OH)<sup>4</sup> .

for kaolinite group is Al2

mula for illite is (K, H)Al<sup>2</sup>

ing sequence.

general formula.

ing the even growing number of clay applications in material science.

4 Current Topics in the Utilization of Clay in Industrial and Medical Applications

tics to recognize its usefulness, and introduced several products.

mica, feldspar, illite, and montmorillonite [2].


**Table 2.** Sheet structure for the layers of clay minerals [7].

layer; 2:1 clay mineral would contain two tetrahedral sheets and one octahedral sheet sandwiched between the two tetrahedral sheets (montmorillonite is an example of clay mineral having 2:1 sheet structure); and 2:1:1 clay minerals are composed of an octahedral sheet adjacent to a 2:1 layer [6]. The sheet structure for the layers of various clay minerals with the possible charge is shown in **Table 2** [7].

Natural reserves of montmorillonite are present in various parts of the world. An earliest discovery of montmorillonite was indicated in 1847 in Montmorillon in the Vienne prefecture of France. However, the use of montmorillonite for medicinal purposes may be in over 200 cultures including the ancient Egyptians, pre-Aztec Amargosians, natives of Mexico, South Americans, and North Americans [8].

The names used for montmorillonite are known in different languages, including montmorillonita (Portuguese, Catalan, and Spanish), montmorilloniet (Dutch), and montmorillonit (German, Hungarian, Slovak) [9].

The major montmorillonite deposits found at five places include Himalayas (China), Urals (Pakistan), Caucasians (Georgia, Russia), Andes (Peru, Ecuador), and Wasatch (UT, USA) [10].

Theoretical formula and structure is indicated in **Figure 1** [13]. The important natural physical properties of montmorillonite are given in **Table 3**. The best field indicators are softness, color,

The variation in the chemical formula of montmorillonite is possible resulting from the modifiable structure. The cation substitution introduces charge imbalance. Therefore, the chemical composition can vary. The exact theoretical formula is never seen in nature [13]. However, the

The chemical formula for montmorillonite discovered at Montmorillon, France, is (Ca0.14

The oxide composition comprises silicon and aluminum oxides; however, it was predominantly calcium montmorillonite discovered at Montmorillon. The dominant fractions were

The elementary molecular structure is based on units comprising silica tetrahedron and aluminum octahedral. The cation Si+4 is fourfold and possesses tetrahedral coordination with

A layered structure is influenced by the presence of charge in tetrahedral and octahedral sheets. Isomorphous substitution in clay mineral mainly produces charge. Isomorphous

was slightly more than the 50% of total oxides.

 1.02H2 O.

Montmorillonite: An Introduction to Properties and Utilization

http://dx.doi.org/10.5772/intechopen.77987

7

water, soapy feel, and expansion with water absorption.

structure in nature in any form consists of water molecules.

Na0.02)∑ <sup>=</sup> 0.16 (Al1.66 Mg0.36 Fe0.04) ∑ <sup>=</sup> 2.08 (Si3.90 Al0.10) ∑ <sup>=</sup> 4.00O10 (OH)<sup>2</sup>

oxygen, while the cation Al+3 occurs in sixfold or octahedral coordination.

**Figure 1.** Theoretical formula and structure of montmorillonite (source: Nanocor Inc., IL (USA) [13]).

SiO2

and Al2

O3, where SiO2
