What is Rock ?
Rock is a solid integrated
form of mineral grains or naturally occurring solid mass or it can become
cemented together. For small size of rocks is used to call as pebbles.
Generally geologists classify this natural rock according to the way they are
formed in nature. A stone is formed from rocks after it has been trimmed or
dressed or polished into tiny pieces.
Uses of Rock/stones:
· Structure: Stones are used for foundations, walls,
columns, lintels, arches, roofs, floors, damp proof course etc.
· Face works: Stones are adopted to give massive
appearance to the structure. Walls are of bricks and facing is done in stones
of desired shades. This is known as composite masonry.
· Paving stones: These are used to cover floor of
building of various types such as residential, commercial, industrial etc. They
are also adopted to form paving of roads, foot paths etc.
· Basic material: Stones are disintegrated and converted
to form a basic material for cement concrete, morum of roads, calcareous
cements, artificial stones, hallow blocks etc.
· Misalliances: Stones are also used for:- (i) ballast for railways
(ii) flux in blast furnace
(iii) Blocks in the construction of
bridges, piers, abutments, retaining walls, light houses, dams etc.
Classification of Rocks:
Basically building stones are obtained from rocks occurring
in nature and classified in the following three ways.
1. Geological classification.
2.
Physical classification.
3. Chemical classification.
All Types of rocks and its examples
I. Geological Classification:
Following are some examples of geological rocks –
a. Igneous rocks: Rocks that are formed by cooling of Magana (molten or pasty rocky material) are known as igneous rocks. Eg: Granite, Basalt and Dolerite etc.
b. Sedimentary rocks: these rocks are formed by the deposition of production of weathering on the pre-existing rocks. Examples: gravel, sandstone, limestone, gypsum, lignite etc.
c. Metamorphic rocks. These rocks are formed by the change in character of the pre-existing rocks. Igneous as well as sedimentary rocks are changed in character when they are subject to great heat and pressure, Known as metamorphism. Examples: Quartzite, Schist, Slate, Marble and Gneisses.
II. Physical Classification:
This classification based on
general structure of rocks. According to this, the rocks are classified into
three types
a. Stratified Rocks:- These rocks posses planes of stratification or cleavage and such rocks can be easily split along these planes Ex: sedimentary rocks
b. An stratified rocks: The structure may be crystalline granular or compact granular. Examples: Igneous rocks and Sedimentary rocks affected by movements of the earth.
c. Foliated Rocks: These rocks have a tendency to split up in a definite direction only. Ex: Metamorphic rocks.
III. Chemical Classification:
According to this
classification rocks are classified into three types.