C lay is the earthy hydruou aluminium silicate formed by the decomposition of preferably feldspathic materials which possess the property of plasticity when suitably tempered with water. The ciitaria for any material to be called as clay are, (i) it must be natural material with plastic properties, (ii) It must have essential composition of particles of very fine size, and (iii) The essential composition of crystalline fragments of mineral should be hydrous alumino-silicate. The commercial value of clays depends mainly on their physical properties like plasticity, strength, shrinkage, vitrification range and refractoriness, fired colour, porosity and absorption. The various clays namely ball clay, china clay & fire clay are found in the state.
Ball clay is a plastic sedimentary clay. It imparts high green strength and good workability to pottery bodies. The name 'Ball clay' derives from the original method of production which consisted of cutting out the clay in open pits into cubes or balls. The primary mineral phase is Kaolinite. Micaceous minerals and quartz are the dominent minerals present as impurities along with minor amount of tourmaline, feldspar, chlorite, montmorillonite, interstratified clay minerals, various titanium compounds, siderite, pyrites, limonite and haematite.
Ball clays have no definite chemical composition and in that respect they do not differ greatly from china clays However, it often contains a large proportion of silica and is more plastic. More than 850/0 of the particles are finer than 1 micron. A linear dry shrinkage of about 12% is often regarded as a permissible maximum limit for a ball clay.
Most of the clays range between 125 and 250 p.s.i. in tensile strength and between 150 and 500 p.s.i. modulus of rupture. The fired colour ranges from white to buff and PCE is generally below cone 33.
Ball clay is used in manufacture of sanitaryware, floor & wall tiles, electrical porcelain & semivitreous whiteware to the extent of 35% in body composition.
The important deposits of ball clay are located in the states of Andhra Pradesh, Kerala
& Bikaner district of Rajasthan.
Rajasthan contributes about 40% of ball clay to the total country's production. There are81 mining leases for ball clay in the state and about 544.370 tonnes mineral was produced during the year 1997-98. The description of the deposits in the state is given below :
Bikaner district
Kolayat-Kotri-Gurha : Kolayat-Gurha belt extend from Kolayat in the south to Gurha in the north over a distance of 15 km. There are three horizons of clay, the richest middle horizon has five clay bands alternating with ferruginous sandstone, grits & siltstone. The clay bands are 1.5 to 4 m in thickness. The two bands in the lower horizon are 1.5 to 2.5

m. in thickness. The upper horizon has a single clay band varying from 2m to 6.5 m. in thickness. The clay is white often interlayered with impure clays, highly plastic, fine grained and composed mostly of kaolinite. The water of plasticity is about 27.6%.
Chandi: The deposit occurs 1 km. north of Chandi. The thickness of the clay band varies from 1 to 8 mt. Estimated reserve is 3 million tonnes. The PCE value of orton cone is 30-31 i.e. 1650-1680oC The water of plasticity 27.6%, fires of a cream colour.
Mudh : Mudh deposit lies N.W. of village Mudh, about 4.8 km. from Sri Kolayatji
Railway station; clay is greyish white in colour, practically free from grit and is mainly kaolinite, fine grained; good plasticity. Water of plasticity 27.6% and has a clay substance of 61.2% PCE values of orton cone 30-31 i.e. 1650-1680oC, fires to a cream colour. The reserves at Mudh and Kotri are expected to be about 2 M.T.
Gurha : A large clay deposit is located near village Gurha. The deposit is very extensive with an average thickness of about 3 m. The estimated reserve is about 2 M.T. The clay is dull white in colour, slakes in water readily and has a soapy hand feeling.
The other minordeposi ts in districts are Kharicharan, Nal, lndo -ka-Bala Suraj ki Dhan etc.
Ball clay's also reported from Khardia, Literia in Pali district; Chhor, Devikot, Kita,
Manda in Jaisalmer district; Mundwa, Sardena, Nimri Chandawatan, Haludah, Khajwana,
Rolchandewaten, Indawar in Nagaur district and Bhopa-Parmel-ki-Dhani in Barmer district.
The name 'Kaolin' is said to have originated from the Chinese world kao liaug, meaning high ridge a local designation for the area where white china clay was found. It is an altered product derived by weathering or hydrothermal action from rocks rich in feldspar.
Crude China clay consists mainly of three substances, viz (i) true clay particles or clay substances (ii) Quartz grains of various sizes and (iii) Undecomposed feldspar. The china clays may be of primary, secondary or residual in origin.
The colour of Kaolin in the green state may vary from white, pale cream, cream to light grey depending on the nature and amount of impurities present in them. It is soft witha soapy touch and consists of small flakes of scales. The true sp. gr. of kaolin ranges from
2.55 to 2.65 and when dispersed completely in water, about 60% of the particles are below 2 micron.
China clay is the basic ingredient in ceramic body composition for the manufacture of porcelain glazed earthen-ware and stoneware. Good quantity of china clay is also used in paper, textile & rubber industries and limited quantity is used in manufacture of pharmaceuticals & insecticides. .
Occurrences in Rajasthan
Rajasthan contributes about 35 % of china clay to the total country's production. There are 65 mining leases for china clay in the state and about 184430 tonnes minerals was produced during the year 199798 . The description of the deposits in the state is given below:

Bhilwara district
Kotri & Jahajpur : Extensive good quality clay deposits are reported from Kotri &
Jahajpur area. These deposits are quite suitable to various ceramic products. The silica ranges from 46 to 54% & alumina ranges from 29-34%. Iron content varies but not more than 1.12% . The firing characteristics showed white to creamish white colour at 1400oc.
The estimated reserv~s are about 1.5 & 2.5 m.t. respectively.
Other small deposits in district are Bhadupur, Mangrop etc.
Chittorgarh District
Eral : Deposits occurs east of Chittorgarh fort. Clays is greyish white, fine grained and fairly plastic. It analyses Si0
2
- 58.35, A1
2
0
3
- 27.79, Fe
2
0
3
- 0.85 ,Na
2
O & K
2
O - 0.66 and
LOI - 9.6% The reserves is about 4 M.T.
Sawa : Fairly extensive deposit occurs near village Sawa 20 km. south of Chittorgarh. It is greyish white, fires to a buff colour and is moderately plastic and showing Si02-
66.78%, A1203- 23.59% Fe203-1.31 %, Na2O-K2O 1.33%, and LOI- 5.660/0. The estimated reserve is about 6 M.T.
Other china clay deposits/workings are located at Bansi, Badi Sadri, Bhagawanpura,
Chingsi and white clay at Kantharia, Binot and Samor.
Jaipur district
Small China clay deposits are located near Jorda, Fetehpura, Buchara Khelno,
Kishorepura, Sonarupa, Gol, Jonpura etc. villages.
Sawaimadhopur district
Small occurrences/workings of China clay were noticed near villages Methasur, Phalodi
Raesena, Basu etc. villages.
Sikar District
Clay deposits are located near Mahawa, Purushottampura villages.
Jodhpur district
Occurrences/working of low grad clay is reported from Jewaria, Jodhpur, Ramasani-
Rampura, Kheradia villages.
Udaipur district
Karbariyon-ka-Guda: This deposit is located 7 km. ESE of Udaipur. The thickness of the clay band is more than 17 m. The inferred reserves are of the order of 3.99 M.T.
Small occurrences / workings were also noticed in near Manak Chowk area of Bundi district;, Chawondia, Kirala, Kharda-ki-Dani, Jeoria, Rupnas, Kaproda villages of Pali district. Bararo, Sarolkhera area of Kota district; near village Phagwara in Nagaur district;
Goredang, Malia, Lugia area of Ajmer district; near village Gunga, Nagurda of Barmer district; in Girwari of Jhunjhunu district.

In Nagaur district while carrying out exploratory drilling for lignite extensive deposite of clay was encountered but the availability is subject to opencast mining for lignite.
Ball Clay
Ball clay is highly plastic variety of clay of Kaolinite group like china clay and fireclay, but has less refractorines china clay, except that the ball clay contains a large proporation of silica.
The main utility of ball clay lies in its plasticity, high b~ing qualities and tensile strength.
It is therefore used in blend with non-plastic to semi-plastics clays for obtaining requisite plasticity. It is added in various proporations for the preparation of body composition of vitreous sanitarywares, bath tub tiles, hotel chinawares, floor and wall tiles, spark plug, porecelain etc.
The ISI has prescribed the following specification (IS: 4589 -1968) for ball clay for use in the ceramic industry:- The material shall be in the form of lumps of powder, free from any foreign matter and shall be highly plastic when wet. The lumps shall slake in water and form a smooth suspension when disperesed. The colour of the material when fired at
1350
0
C shall be light grey or light cream and free from any specks or patches.
Chemical Analysis
Fe
2
O
3
TiO
2
Fe
2
O
3
+ TiO
2
Al
2
O
3
by weight
LOI by wight
-
-
-
-
-
1.5% max.
1.5% max.
2.75% max.
25% min.
10.5% min.
The following grade for ceramic industry for estimation of reserves of ball clay have been recommended.
Chemical Physical
Fe
2
03
Ti0
2
A1
2
O
3
LOI
Fe
2
O
3
+ Ti0
2
-
-
-
1.5 max. Fired colour :-
1.5 max.
- 25% min.
- 10.5% min.
Light grey or light cream.
Plasticity Highly plastic when wet.
2.75% max. (by weight) Free from any foreign matter
China clay, also called kaolin falls under kaolinite felspars, granite, gneiss and pegamtite rocks by hydrothermal action of aqueous solution. Chinaclay usually carried some impurities in a small quantity such as silica, iron, magnesium, titanium, calcium, potassium, sodium oxides, mica, tourmaline of china clay depends much upon the impurities present. Chinaclay is mainly used in ceramics, textiles, paper, rubber, paints,

cosmetics and pharmaceuticals industries. it is also used in insecticides, white cement and refractory bricks manufacturing.
The uses and specifications of chinaclay in different industries are discussed below.
(A) Ceramics: The ISI has not standardised any specification for use of chinclay in ceramic industry. However, for the manufacture of ceramic products good quality chinaclay is required which should have water of elasticity 32%, shrinkage after drying should not be more than 7%, and total shrinkage after firing at a temperature of 1300° C not more than 10-14%. The colour should be perfectly white after firing. Grit should be low. For the manufacture of ordinary crockery and ceramic wares, presence of grit up to
2% is tolerated. But for the manufacture of high class crockery, grit below 10/0 is generally preferred. In the manufacture of high class ceramic products, the presence of lime, magnesia, iron oxides, alkalies and other impurities upto 2% is not harmful. Excess of iron, however, may colour the products. Also for the manufacture of electrical switches, the iron content should be as low as possible.
(B) Textile and Paper Coating: Chinaclay is utilised in textile industry as a sizing and packing material. For this purpose, the clay should be white in colour without tinting.
Grit is the most objectionable ingredient. Oxides of magnesium and iron should be as low as possible. Dull white clay is utilized in making coloured and khaki cloth.
Chinaclay is used for paper coating purpose in order to provide a smooth, even surface and to impart a glaze. Various grades of paper quality chinaclay of fine mesh are used depending upon the quality of the paper required to be manufactured. The whiteness, ink absorption, chemical inertness, uniformity of particle size and retentive properties determine the suitability of chinaclay for use in paper coating.
The ISI (IS: 505-19978) has standardised specifications for chinclay for use in textile and paper coating industry as follows.

(C) Rubber: In rubber industry, chinaclay is used as a filler and as a reinforcing and stiffening agent. For these purposes, light weight clay having a specific gravity 2.5% is tolerated. It should be of fine mesh and should be absolutely free from copper, which is undesirable in rubber goods. The ISI (IS: 505-1978) has standardised the specification as given below.
(D) Paints: Chinaclay is used as an extender or suspending agent in the manufacture of white paint. The ISI has not standardised any specification for this use. However, the properties like antisetting and tinting effect, colloidal nature, softness, freedom from grit, white colour and fine size are some of the qualities which make chinaclay suitable for use in paint and distemper manufacture.
(E) Cosmetic and Pharmaceutical: There is no ISI specification. Superfine chin clay is utilized for specification. Superfine chinclay is utilized for the mal1ufacture of products like powder, adhesives, surgical plaster, lotion and ointment for external use, porcelain for dental preparation. Chinclay for medicinal purposes must be free from lead, arsenic and other metals which the human body will not to erate. It should have no frothing.
Particle size, frothing factors and sedimantation volumes are the three important factors considered in the selection of chinaclay for pharmaceutical purposes.
(F) Filler in paper: Inferior grade chinaclay may be used in the manufacture of brown paper, new print, hardboard paper and straw paper board. The ISI (IS: 50501978) have standardised the specifications as given below:

(G) Insecticides: Chinaclay is used in the manufacture of disinfectant like DDT. The ISI
(IS: 505-1978) has standardised the specifications for use of china clay in insecticide industry as given below.
For uses of chinaclay in other industries like white cement and refractory bricks, there is no standard specification whatsoever. In case of manufacture of refractory bricks, the coarse fraction of chinaclay from the sedimentation tank is used.
After examining for specifications standardised by ISI and the current trends in the user industries, following end use classifications of reserves have been recommended.
After examining for specifications standardised by ISI and the current trends in the user industries, following end use classifications of reserves have been recommended