Slate and Phyllite
 

Commercially, the slates are defined as layered stone that can be split into slices of thickness ranging from 8 to 14 mm. Slates/Scihists are generally fine grained and occur in various shades of grey to steel grey, greenish grey, dark grey, purplish grey, brownish, ash and sometimes with other pleasing colours. Slates/Schists have varying degree of hardness. The harder ones are being sometimes used for flooring.
These are low cost decorative stones having wide applications after cutting for use in interior as well as exterior decorations.
Schist and slate stones are argillaceous rocks having different grades of metamorphism. Certain planes of easy split called 'schistosity', are developed in these rocks due to metamorphism, which make these rocks suitable for decorative use. The slates/schists having good and even cleavages are valued much. The planes of cleavage are related solely to the direction of pressure to which the material was subjected and not to the bedding plane.

Micaceous and chlorite slates/schists are generally of good quality.
These are used for roofing, paving, shelves and flooring purposes in the rural areas in and around the places where it is mined. Now a days slates/schists are cut in to tiles and used for wall claddings. Slates are also used for making school slates.

 
Etching on Slate Stone
 
Geographical Distribution

Slates, schist and phyllites of dimensional use are found associated with Delhi and Aravalli Supergroup of rocks in parts of Ajmer, Alwar, Jaipur, Sawai Madhopur, Bharatpur, Bundi, Pali, Tonk, Udaipur and Chittaurgarh districts. Slate deposits of Alwar are conspicuous both in regard to quality and quantity.

Besides, Bar conglomerate in Pali district and calc-schists in Ajmer district, mica schist in Bhilwara district etc. are quarried for use as roofing and flooring slabs.

Districtwise distribution of Slates, schist and phyllites is shown below:

Ajmer: Sheopura, Lulawa, Nai Khurd (Beawar).

Alwar: Basai, Kayasa, Kund (Behrod).

Tonk: Devli, Dhuni, Anwa, Uncha.

Pali: Bar.

Bhilwara: Badnor, Tikar.

Dungarpur: Balwara.

Chittaurgarh: Gosunda.

Udaipur: Godan, Gogunda.


 
Panther Jhalawar
Makarana Albeta Makarana Albeta Makarana Albeta Makarana Albeta
Deoli Tonk
Makarana Albeta Makarana Albeta Makarana Albeta Makarana Albeta
Copper Tonk
Silver Grey Bhilwara
Future Prospects
Slates have potential export market. The multi coloured slates of Kund, Behror, tehsil & distt. Alwar have export demand for a long time. It is used for roofing, tiling, for wall paneling, wall-cladding etc. Copper-red, green, grey, silver-grey coloured slates of Badnor and Tikar (Bhilwara) and Dhuni, Anwa (Tonk) are forming export market. Pali, Dungarpur and Bundi districts are also emerging as slate producer districts. Chief importers are Australia, Netherland and Switzerland. Export can further be increased with the application of better mining and processing techniques.
 
Technical Information of Slate
Technical Details
    
Water Absorption,
% by weight
Modulus of rupture,
N/mm2
Acid Resistance
(Whether Resistence)
Depth of softening mm
Abrassion resistance
to wear
ASTM/
Indian Standard

    
C-121 C-120 C-217 IS 1237 Guidelines
Area
      Avg. Wear mm Mxm. Wear mm
Panther Jhalawar 2.0 2.9 0.04 1.7 1.9
Deoli Tonk 2.1 1.9 0.06 5.7 5.9
Copper Tonks 1.2 14 0.09 11.7 11.7
Silver Grey Bhilwara 0.3 46 0.05 26 2.8
 
Production, Sale value and revenue from slates for last five years is given below: District wise stastistical details are as under:
Year No. of
Lease
Production
(thousand
tonnes)
Sale
Value
(thousand
rupees)
Revenue
(thousand
rupees)
1997-
1998
32 8.140 2923.60 550.990
1998-
1999
42 6.56 4054.00 1126.935
1999-
2000
44 12.019 105.450 1383.360
2000-
2001
43 7.775 36.730 1147.220
2001-
2002
37 8.937 16.350 968.470
District No. of
Lease

Production
(thousand
tonnes)

Revenue
(thousand
rupees)

Alwar 23 5.034 740.00
Bharatpur 3 0.056 57.36
Bhilwara 2 - 35.03
Bundi 5 03.951 110.29
Dausa 1 0.028 25.79
Toak 3 0.0670 0.00
Total 37 8.939 968.47