Stones
Stones are inert material for engineering construction. They are available naturally and artificially too, made up of two or more minerals.
Stones are mainly classified into three categories:
- Geological Classification
- Chemical Classification
- Physical Classification
Geological Classification
Geological classification subdivided into 3 more classification.
- Igneous Rocks
- Sedimentary Rocks
- Metamorphic Rocks
Igneous Rocks
Inside the surface of earth there is high temperature which leads to great extent fusion at little or negligible pressure. Molten magma tries to come out from the surface of earth through cracks and weak portions. this rocks which are formed by molten magma is termed as Igneous Rocks. This rocks are formed either at surface or below.
This is further subdivided into:
Plutonic
When rocks are formed due to molten magma at greater depth from the surface of earth they are termed as Plutonic Igneous Rocks. In this case cooling process is very slow and structure formed is coarse grained crystalline. Also termed as Intrusive Igneous Rocks
Most commonly used building stones are of this type.
Example: Granite
Hypabyssal
When rocks are formed due to molten magma at shallow depth from the surface of earth they are termed as Hypabyssal Igneous Rocks. In this case cooling process is quick and structure formed is finely grained crystalline.
Example: Dolerite
Volcanic
When rocks are formed due to molten magma at the surface of earth they are termed as Volcanic Igneous Rocks. In this case cooling process is extremely quick and structure formed is extremely fine grained crystalline. Also termed as Extrusive Igneous Rocks
Sedimentary Rocks
This types of rocks are formed due to gradual deposition of weathered products at a location one on another. all type of deposits transport from one location to other due to transporting agents. Such as wind, water and frost etc.
They are subdivided into followings:
Residual Deposits
The rocks which are remains at the site of it's origin are termed as residual deposits.
Sedimentary Deposits
The rocks which are transported from one location to another location and during the transport remains in suspension are termed as sedimentary deposits.
Chemical Deposits
The rocks are formed due to physio-chemical process are termed as chemical deposits.
Organic Deposits
This are the rocks which are formed due to deposits of organisms.
Example of Sedimentary Rocks are:
Sandstone,
Limestone,
Gypsum,
Lignite,
Shale(oil, black)
Metamorphic Rocks
This types of rocks are formed due to excessive heat and pressure on to the existing rocks such as igneous and sedimentary. This particular process termed as metamorphism and the rocks formed due this action are termed as metamorphic rocks.
Existing rocks already in certain equilibrium, but metamorphism convert it to different level of equilibrium which form different property rocks. In metamorphism process some constituents of older which are weak transform into new constituents. New composition formed accordingly the surrounding atmosphere.
Metamorphism occurs due to following agents
- Heat - change if temperature
- Pressure - movement of rocks and earth crust
- Chemical Fluid - chemical agent into liquid
There are four form of metamorphism:
| Thermal | Heat is predominant factor for formation of rocks |
| Cataclastic | Pressure only responsible for formation of rocks. Heat effect is not consider due to low temperature. |
| Dynamo-Thermal | Increase in temperature with depth, which caused increase in stress and rocks are formed. |
| Plutonic | Formed due to uniform pressure and heat after certain depth. |
Examples of Metamorphic Rocks:
Marble
Quartz
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