Common building stones, their compositions, properties, uses and occurrence are given below:
1. Granite:
Composition:
It is igneous rock. Its main constituent minerals are Quartz, (hard and least affected by carbon dioxide and water) Felspar (crystalline, lustrous, readily attacked by atmospheric agencies) and Mica (dark grey, black or brown in colour, soft, readily affected by chemicals and atmospheric agencies).
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(i) Its specific gravity is 2.64 and absorption less than 1%.
(ii) It has mottled appearance.
(iii) Significantly strong and durable.
(iv) Finely grained granite takes a fine polish.
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(v) Crushing strength varies from 110 to 140 MN/m2.
(vi) It has least fire resistance as it cracks under a strong fire.
(vii) Its colour depends upon that of felspar.
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(i) Fine grained granite is suitable for ornamental columns, plinth etc., as it takes a polish.
(ii) Owing to the hardness, weight and durability of granite it is considered most suitable for the construction of sea walls, light houses, bridge piers etc.
(iii) Large pieces are used as building blocks, the smaller as road metals or railway ballast and the chippings for the manufacture of concrete or artificial stone.
Occurrence:
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Jhansi (U.P.), Jabalpur (M.P.), Ajmer (Rajasthan), Dalhousie and Kangra (Himachal). The best specimens are available in Secunderabad (Andhra Pradesh).
2. Basalt or Trap:
Composition:
It is an igneous rock (silicious variety). The main constituents are silica, alumina and felspar.
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(i) Very hard and tough.
(ii) Heavier than granite.
(iii) Has greenish grey to dark grey colour.
(iv) Crushing strength varies from 70 to 80 MN/m2.
(v) Specific gravity = 2.96.
(i) Suitable for paving sets and as a road metal.
(iii) Used for the manufacture of artificial stone.
(iii) Used as aggregate in concrete.
Occurrence:
Madhya Pradesh and Deccan traps (along western coast) and Rajmahal trap (Bihar).
3. Slate:
Composition:
It is a metamorphic rock (Argillaceous variety). It is composed of alumina mixed with sand or carbonate of lime.
(i) Its specific gravity is 2.8.
(ii) A good slate is hard, tough and fine grained.
(iii) It has grey or dark blue colour.
(iv) It can be split into thin sheets.
(v) Its crushing strength varies from 60 to 70 MN/m2.
(vi) It is non-absorbent.
(vii) When struck with a light hammer, it produces a sharp metallic ring.
(viii) Its durability is good.
Uses:
(i) Used for making electrical switch boards.
(ii) Because of its non-absorbent property, it is suitable for use in cisterns, urinals partitions, etc.
Occurrence:
Gurgoan (Haryana), Gurdaspur (Punjab), Cuddadh (Andhra), Chanda (Maharashtra), Chindwara (M.P), Bijapur (Mysore), Alwar (Rajasthan), Chamba, Simla, Kangra (Himachal Pradesh), Baroda (Gujarat).
4. Gneiss:
Composition:
It is a metamorphic rock. It is also sometimes called stratified granite as it occurs in somewhat parallel layers. Its constituents are the same as granite, i.e., quartz and felspar.
(i) It can be readily split into slabs.
(ii) It is more easily worked than granite.
(iii) As it is available in different colours, it is used for ornamental and decorative purposes.
(iv) It is reasonably good material for street paving.
Occurrence:
It is largely found in Madras State, Mysore and Bihar.
5. Sandstone:
Composition:
It is a sedimentary rock of silicious variety. It contains sand or quartz cemented by lime, mica, magnesium, aluminium, oxide of iron or by a mixture of these materials. Sometimes fragments of limestone, mica or felspar are also present.
(i) Its structure shows sandy grains.
(ii) Its usual colours are white, grey, brown, pink etc.
(iii) Its specific gravity is 2.25.
(iv) Crushing strength varies from 35 to 40 MN//m2.
(v) Fine grained stones are strong and durable.
(vi) The sandstone of thin-bedded variety is called flag stone. It splits easily into large slabs along the bedding.
(vii) The rock composed of angular sharp edged sand grains is called grit; it is adequately strong and heavy and is used in heavy engineering works.
(viii) The sandstone that can be cut easily with mallet and hammer into blocks for building is referred as free stone.
(ix) Its durability depends upon the nature of cementing material. The quantity of sandstone is poor if it is porous or contains lime.
Uses:
(i) The fine grained and compact variety is suitable for ashlar work, mouldings, carvings etc.
(ii) The rough and coarse grained stone is employed for rubble work.
Occurrence:
The best variety stones which can easily be quarried in large flawless blocks are available in Mirzapur; Chunar; Fatehpur Sikri; Gwalior (M.P.); Hemanagar near Ahmedabad (Gujarat); Nagpur (Maharashtra); Kangra and Dharamsala (H.P.), Shahpur and Kasauli Rajpur, and Jabalpur; Dehri; Mandhum and Ranchi (Bihar); Cuttack and Mysore.
6. Limestone:
Composition:
It is a sedimentary rock of calcareous variety. When in pure state it contains CaCO3, but frequently is mixed with MgCO3 and small amount of silica and alumina. When both MgCO3 and CaCO3 are present nearly in equal proportion it is known as Dolomite.
(i) Its specific gravity is 2.6.
(ii) It is available in brown, yellow and dark grey colours.
(iii) Crushing strength = 52 MN/m2.
Uses:
(i) It is used in large quantities in blast furnaces, bleaching, tanning and other industries.
(ii) If compact and fine grained it may be used as stone masonry for walls and paving set in floor.
(iii) It is used as road metal (when better materials like trap, basalt or granite are not available).
Occurrence:
It is found in Alwar (Rajasthan), Hoshiarpur (Punjab), Simla (H.P.), Mirzapur, Ranchi (Bihar) and Mysore etc.
7. Marble:
Composition:
It is metamorphic rock of calcareous verity. It is changed from limestone. It is crystalline hard compact stone having CaCO3 as the main constituent.
(i) It is available in white, yellow, grey, green, red, blue and black colours.
(ii) It is very hard and takes a fine polish.
(iii) Its specific gravity is 2.72.
(iv) Chrushing strength varies from 50 to 60 MN/m2.
(v) It can be easily worked.
(i) It is used for carving and decoration work.
(ii) It is also used for steps, wall linings, electrical switch boards, table slabs and columns.
Occurrence:
White marbles of high purity are found in Jodhpur and Ajmer (Rajasthan) and Jabalpur (M.P.), Green marbles in Baroda (Gujarat), black marbles in Jaipur (Rajasthan) and yellow marbles in Jaisalmer (Rajasthan).
8. Kankar:
Composition:
It is an impure limestone containing 30 percent of clay and sand.
(i) It is available in grey or khaki colour.
(ii) It has porous structure.
(iii) It occurs in solid layers or as irregular shaped modules a few metres below the surface.
(iv) Hard kankar is adequately durable
(i) Nodular kankar when burnt yields excellent hydraulic lime; when clean, hard and tough is used as road metal.
(ii) Hard kankar is employed for foundations of buildings.
9. Laterite:
Composition:
It is basically igneous but not completely metamorphic. It is sandy clay stone containing high percentage of iron oxide.
(i) It has a porous and cellular structure.
(iii) It is readily quarried in blocks.
(iii) It is of reddish, brown, yellow, dark brown and black colours.
(iv) Its specific gravity varies from 2 to 2.2.
(i) Laterite blocks are suitable as building stones.
(ii) Nodular laterite proves a very good road metal.
Occurrence:
It is available in some districts in Bihar and Orissa, in Madhya Pradesh, in Kangra (Mysore) and in Burma.
10. Moorum:
Composition:
It is a decomposed laterite.
Characteristics:
It has deep brown or red colour.
(i) Due to its rich red colour, it is used in surfacing fancy paths and garden walks.
(ii) It serves as a fine blind age for metaled rods.
Occurrence:
It is found in some parts of Madhya Pradesh.
11. Gravel:
It is mixture of rounded water worn pebbles of any kind of stone with sand. It is usually available in river beds. The size of the pebble varies from minute grains to 8 cm in diameter. It is suitable for surfacing road and is also used in concrete.
12. Chalk:
It is pure, white limestone. It is soft and can be easily powdered. It is largely used for the manufacture of Portland cement. It is also used for marking and as a colouring matter. It is unsuitable for building purposes.
13. Shingles:
These are large water-worn pebbles found in river beds. Broken shingles are used in concrete and as road metal when no better stuff is available at reasonable cost.
14. Quartzite:
It is composed of silica and is dense, hard and glassy in structure. Some of the varieties are considered as the hardest and strongest type of building stones. It is strong and durable and used as road metal or railway ballast or in concrete.