Commonly Used Building Stones in India

COMMONLY USED BUILDING STONES IN INDIA

The following are the some of the commonly used building stones widely used in India:

(i) Marble:

Marble is the most familiar variety of metamorphic rock. It's chemically calcareous, and is formed from crystallized limestone by metamorphism. It is chiefly composed of calcium carbonate. Its specific gravity is 2.65 and crushing strength is 70 to75N/mm2. The usual color of marble is white, but it is also available in different shades of colors such as grey, black, red, brown, yellow and combination of any of these. It can take a fine polish due to its crystalline structure. It is less durable and can be easily carved. Hence it is most suitable for sculpture work, flooring, steps, facing and ornamental works in decorative panels.

(ii) Granite:

Granite is the most common variety of igneous rock. The hardest and most durable granites contain a greater proportion of quartz and smaller proportion of feldspar and mica. Its specific gravity is from 2.6 to 2.7 and crushing strength is 100 to 250 N/mm2. It is heavy, hard, strong, durable and crystalline in nature. It is available in wide ranging colours like grey, green, brown and pink and red. Because of its uniform structure, granite can be quarried in large blocks. Medium-grained stone is best fitted for building construction. Fine-grained stone can be carved and polished. They are also used for bridge piers, river walls, and for dams. They are used as kerbs and pedestals. Granite is also used for monumental and and flooring works. Polished granites are used as table tops and wall cladding.

(iii) Sand stone:

Sand stone is the most familiar variety of sedimentary rock. It's physically stratified, chemically siliceous, and is chiefly composed of quartz .Other minerals such as felspar, mica, magnetite etc. are also present. The specific gravity varies from 1.85 to 2.7 and crushing strength ranges from 20 to 170 N/mm2. They are found in a variety of colours like white, grey, red, brown, yellow and light brown. Weathering of rocks makes it unsuitable as a building stone. They are used for masonry work, for dams, bridge piers and river walls. If required, it is suitable to use sand stones with silica cement for heavy structures.

(iv) Basalt:

Basalt is the most common variety of igneous rock, formed by solidification of lava on the earth's surface due to volcanic eruption. The structure is medium to fine grained and compact. Some basalt extend step like appearance and are called as traps. They are chiefly composed of silica, alumina and feldspar. The specific gravity varies from 2.9 to 2.96 and crushing strength ranges from 200 to 350 N/mm2. They are greenish grey to black in color. They are used as road metals, aggregates for concrete and also in rubble masonry works for bridge piers, river walls and dams.

(v) Slate:

Slate is the well known variety of metamorphic rocks, composed of quartz, mica and clay minerals. Having a fine grained structure, they are split along the planes of initial bedding easily. The specific gravity varies from 2.6 to 2.7 and crushing strength ranges from 100 to 200 N/mm2. They are available in various shades of grey colour such as dark grey, greenish grey, purple grey and black. It offers good abrasive resistance. Generally slates are used for steps, shelves, roof tiles, pavements and black boards..

(vi) Limestone:

Limestones are of sedimentary origin, carbonate of lime being their principal ingredient. They are fine to crystalline and may have fossils. The stone is called as argillaceous limestone if clay is present. If iron is prevalent, then it is known as ferruginous limestone. When silica predominates, then it is siliceous limestone. They are available in white, light grey to light buff colours. They are mostly used as fillers and powdered limestone has industrial uses.

(vii) Quartzite:

Quartzite is a metamorphic rock, having fine to coarse grained structure. The chief component is quartz, where feldspar and mica are available in small quantities. The specific gravity varies from 2.55 to 2.65 and crushing strength ranges from 50 to 300 N/mm2. They are available in different colours like white, gray and yellow. They are used as building stones, slabs and even as aggregates for concrete.

(viii) Gneiss:

Gneiss is a coarse-grained laminated metamorphic rock, having alternate dark and white bands. Due to the presence of deleterious constituents these stones are generally not preferred. The specific gravity varies from 2.5 to 3.0 and crushing strength ranges from 50 to 200 N/mm2. They are available in variety of colours like light grey, pink, purple, greenish grey and dark grey. They are used in minor constructions and as concrete aggregate.

(ix) Laterite:

Laterite is a metamorphic rock, having porous sponges structure and high percentage of iron oxide. Its specific gravity is 1.85 and crushing strength ranges from 1.9 to 2.3 N/mm2. It is available in different colours like brown, red, yellow and grey. Its strength can be increased by seasoning and can be easily quarried in blocks. Plastering is required on the outer surface, when it is used as building stone.