1.Introduction
Sand Stones : Sandstones are clastic type of sedimentary rocks. Sandstones are quite hard and have great compressive strength. In India, It is available in many colors and shades and streaks, in various regions of India like Gwaliar, Shivpuri, Karuli, Bharatpur, Lalitpur, Dholpur, Kota, Bundi, Bhilwara, Nagpur, Kishangarh and Jodhpur. Interestingly, certain colors of sandstone may be strongly identified with certain regions. These are available in various finishes like calibrated, honed, polished, sandblasted, Natural & flamed. Sandstones are exported in safe exclusive wooden packing in the form of tiles, slabs, mosaics & cobbles. Though sandstones can be used anywhere yet it’s main applications are in floorings, wall cladding, paving (cobbles), backslashes, Shower Walls, Pool Surrounds, Living Room Floors, Entryways & Fireplaces etc.
Monday, January 7, 2008
SANDSTONE
Sandstone
“Fine Touch n feel of Elegance with Saniya Impex”
Sandstone is made of tiny grains of quartz, minerals and feldspar. It is widely used from times of immemorial for residential and commercial construction and decorative purposes. Sandstone is widely used for decorative purposes due to its natural look. It is available in different shades of pink, beige, grey, brown, black etc. Sandstone is a sedimentary rock formed by its own. Most of the sandstone is formed in oceans, lakes and rivers where tiny bits of rock and dirt settle to the bottom. After thousands of years, these layers of sand get buried under tons of more sand and dirt until it is turned into solid rock. The reddish shade of sand stone is due to presence of iron oxides and the greenish shade is due to presence of glaconite. Sandstone when cemented by silica has great strength, making it suitable for structural uses. Sandstone will undergo though various processes like Dressing Cutting/sawing, Surface grinding and polishing and Edge-cutting-trimming into order to make it suitable for final use.
Types of Sandstones
“Widely used for interior and exterior décor with a natural look”
Sand Stone Tiles: It is used for flooring and many types of artifacts in household purpose.
Sandstone Slabs: The sandstone slabs comes in various forms like square, rectangular, round, and oval. The size of the slabs are varies from normal random size of 1'x1' to 10Ft x 2Ft. The thickness supplied ranges from 1 to 10cm or above. These are useful in garden, kitchen, living room, walls, bathroom, etc.
Sandstone cobbles: Sandstone cobble stones are smaller than a boulder and larger than a pebble. Cobbles are fireproof. The sizes in which cobblestones are available are 10x10x8cm, 20x10x8cm, 14x14x6cm, 14x14x8cm, 14x20x8cm. They are used in architectural and decorative purposes.
Sandstone Pebbles: The sandstone pebbles are either round or square in shape. They vary in size from 25-75 mm (2"), 75-125 mm (4") and 125-175 (6") mm. These pebbles are used in fountains, posh lounges, open air theaters, aquaria, parks, homes décor, artificial ponds etc.
Sandstone blocks: They are used to create the monuments and statues from times of immemorial.
Sandstone Strips: These are made in different shapes and sizes by cutting the sandstone as per requirement. They used to create attractive wall designs by using colored strips.
Sandstone bricks: These are used for flooring and walls.
Uses of Sandstones
“Used for architectural purposes and artifacts from times of immemorial”
Flooring
Sandstone used to make your floor to look opulent. It is available in many shades so that you can select the sandstone color matching with your walls and furniture. Sandstone creates a warm ambience adding the sense of completeness in a décor. Flooring can be used using the large sandstone slabs or by using the small tiles. Sandstone flooring adds an exquisite look to your flooring.
Garden
Sand stone is used to add feather in garden’s décor by sandstone furniture, lamps, urns, tables etc.
Garden furniture
Sandstone is best for garden furniture, statues, garden urns, pitchers, miniatures etc.
Garden StatueSandstone is used to make different types of statues. It includes the statues of human, animals, birds, angels etc.
Garden Lamps Sandstone is used to make garden lamps that look nice when electric bulbs put inside them light up.
Garden TablesSandstone is used to make garden tables of various sizes.
Walls
Sandstone is used to raise the walls. It offers the perfect medium for making the walls. Most of the monuments have sandstone walls. It offers both strength and beauty to the wall. The bricks, slabs, blocks of sandstone are used for making the wall. It givers an antique look to the wall.
Pavement
Sandstone blocks, tiles, bricks are used for paving floors and walls. The sandstone pavements are used for residential and commercial purposes.
Landscaping
Sandstone is widely used for landscaping purpose. The stone has natural look. It can cut and shaped as per the requirement. The concept of landscaping offers environmental benefits like trees and vegetation control erosion etc.
Handicrafts
Sandstone is used to prepare a number of attractive handicraft items. It is used to make photo frames, furniture, jewelry boxes, flower case etc. Its color and look has been ideal choice for monuments and various structures. Candle stands of various shapes and colors.
Sandstone Quarries
Sandstone quarries are found in Rajasthan, Madhya Pradesh, few locations in - Gujarat, Orrisa, Karnatka, Tamil Nadu, Andaman and Nicobar and many more places. Indian Sandstone
Properties
Chemical Properties Sandstone has similar chemical composition as of sand. It essentially contains quartz. The cementing materials that bind the sand into a rock are composed of silica, calcium carbonate, or iron oxide. Sand stones are highly resistant to acids, alkalis and thermal impact. Their insolubility in acids and alkalis is about 97%, The percentage of chemicals varies between:
Lime(CaO) ---------------- 0.8% to 0.9% Soda(Na2O) & Potash (Kro) -- 1.0% to 1.2% SiO2 ------------------93-94%Alumina(Al2O3) -------------1.4 to 1.5%Iron(Fe2O3) ----1.5%-1.6%Loss On Ignition(LOI) ------- 1.0% to 1.2%Magnesia(MgO) --------------------0.2 to 0.25%
Physical Properties
Sandstone has hardness of 6 to 7 on Moh's Scale Density 2.32 to 2.42 Kg/m3. The capacity of water absorption is not more than 1.0%. The colors ranges from Sandstone are available in many colors – red, green, yellow, pink, gray and white. The color varies due to variation change in constituents and the binding material. The sandstone comprises of Quartz grains, Feldspar grains and Rock fragment grains. Due to variation in these constituents the shape and color of sandstone varies.
Sandstone Care
Sandstone when handled with care it lasts for years. It is advised to keep sandstone clean and free from scratches. Never use the cleaner that has acid or lemon as it may damage the surface and erode the polish. Cleaner should be neutral. So do not use the bathroom cleaner, grout clear or any cleaner have acid. Never place any hot objects on them directly. While using vacuum cleaner, care should be taken to avoid any kind of scratch.
Sandstone Quarry
Sandstone Care
Sandstone Handicrafts
Resources
Sandstone Chemical Properties
Sandstone Physical Properties
Sandstone Composition
Sandstone Composition
Sandstone Textures
Sandstone Edges
Varieties of Sandstone
“Fine Touch n feel of Elegance with Saniya Impex”
Sandstone is made of tiny grains of quartz, minerals and feldspar. It is widely used from times of immemorial for residential and commercial construction and decorative purposes. Sandstone is widely used for decorative purposes due to its natural look. It is available in different shades of pink, beige, grey, brown, black etc. Sandstone is a sedimentary rock formed by its own. Most of the sandstone is formed in oceans, lakes and rivers where tiny bits of rock and dirt settle to the bottom. After thousands of years, these layers of sand get buried under tons of more sand and dirt until it is turned into solid rock. The reddish shade of sand stone is due to presence of iron oxides and the greenish shade is due to presence of glaconite. Sandstone when cemented by silica has great strength, making it suitable for structural uses. Sandstone will undergo though various processes like Dressing Cutting/sawing, Surface grinding and polishing and Edge-cutting-trimming into order to make it suitable for final use.
Types of Sandstones
“Widely used for interior and exterior décor with a natural look”
Sand Stone Tiles: It is used for flooring and many types of artifacts in household purpose.
Sandstone Slabs: The sandstone slabs comes in various forms like square, rectangular, round, and oval. The size of the slabs are varies from normal random size of 1'x1' to 10Ft x 2Ft. The thickness supplied ranges from 1 to 10cm or above. These are useful in garden, kitchen, living room, walls, bathroom, etc.
Sandstone cobbles: Sandstone cobble stones are smaller than a boulder and larger than a pebble. Cobbles are fireproof. The sizes in which cobblestones are available are 10x10x8cm, 20x10x8cm, 14x14x6cm, 14x14x8cm, 14x20x8cm. They are used in architectural and decorative purposes.
Sandstone Pebbles: The sandstone pebbles are either round or square in shape. They vary in size from 25-75 mm (2"), 75-125 mm (4") and 125-175 (6") mm. These pebbles are used in fountains, posh lounges, open air theaters, aquaria, parks, homes décor, artificial ponds etc.
Sandstone blocks: They are used to create the monuments and statues from times of immemorial.
Sandstone Strips: These are made in different shapes and sizes by cutting the sandstone as per requirement. They used to create attractive wall designs by using colored strips.
Sandstone bricks: These are used for flooring and walls.
Uses of Sandstones
“Used for architectural purposes and artifacts from times of immemorial”
Flooring
Sandstone used to make your floor to look opulent. It is available in many shades so that you can select the sandstone color matching with your walls and furniture. Sandstone creates a warm ambience adding the sense of completeness in a décor. Flooring can be used using the large sandstone slabs or by using the small tiles. Sandstone flooring adds an exquisite look to your flooring.
Garden
Sand stone is used to add feather in garden’s décor by sandstone furniture, lamps, urns, tables etc.
Garden furniture
Sandstone is best for garden furniture, statues, garden urns, pitchers, miniatures etc.
Garden StatueSandstone is used to make different types of statues. It includes the statues of human, animals, birds, angels etc.
Garden Lamps Sandstone is used to make garden lamps that look nice when electric bulbs put inside them light up.
Garden TablesSandstone is used to make garden tables of various sizes.
Walls
Sandstone is used to raise the walls. It offers the perfect medium for making the walls. Most of the monuments have sandstone walls. It offers both strength and beauty to the wall. The bricks, slabs, blocks of sandstone are used for making the wall. It givers an antique look to the wall.
Pavement
Sandstone blocks, tiles, bricks are used for paving floors and walls. The sandstone pavements are used for residential and commercial purposes.
Landscaping
Sandstone is widely used for landscaping purpose. The stone has natural look. It can cut and shaped as per the requirement. The concept of landscaping offers environmental benefits like trees and vegetation control erosion etc.
Handicrafts
Sandstone is used to prepare a number of attractive handicraft items. It is used to make photo frames, furniture, jewelry boxes, flower case etc. Its color and look has been ideal choice for monuments and various structures. Candle stands of various shapes and colors.
Sandstone Quarries
Sandstone quarries are found in Rajasthan, Madhya Pradesh, few locations in - Gujarat, Orrisa, Karnatka, Tamil Nadu, Andaman and Nicobar and many more places. Indian Sandstone
Properties
Chemical Properties Sandstone has similar chemical composition as of sand. It essentially contains quartz. The cementing materials that bind the sand into a rock are composed of silica, calcium carbonate, or iron oxide. Sand stones are highly resistant to acids, alkalis and thermal impact. Their insolubility in acids and alkalis is about 97%, The percentage of chemicals varies between:
Lime(CaO) ---------------- 0.8% to 0.9% Soda(Na2O) & Potash (Kro) -- 1.0% to 1.2% SiO2 ------------------93-94%Alumina(Al2O3) -------------1.4 to 1.5%Iron(Fe2O3) ----1.5%-1.6%Loss On Ignition(LOI) ------- 1.0% to 1.2%Magnesia(MgO) --------------------0.2 to 0.25%
Physical Properties
Sandstone has hardness of 6 to 7 on Moh's Scale Density 2.32 to 2.42 Kg/m3. The capacity of water absorption is not more than 1.0%. The colors ranges from Sandstone are available in many colors – red, green, yellow, pink, gray and white. The color varies due to variation change in constituents and the binding material. The sandstone comprises of Quartz grains, Feldspar grains and Rock fragment grains. Due to variation in these constituents the shape and color of sandstone varies.
Sandstone Care
Sandstone when handled with care it lasts for years. It is advised to keep sandstone clean and free from scratches. Never use the cleaner that has acid or lemon as it may damage the surface and erode the polish. Cleaner should be neutral. So do not use the bathroom cleaner, grout clear or any cleaner have acid. Never place any hot objects on them directly. While using vacuum cleaner, care should be taken to avoid any kind of scratch.
Sandstone Quarry
Sandstone Care
Sandstone Handicrafts
Resources
Sandstone Chemical Properties
Sandstone Physical Properties
Sandstone Composition
Sandstone Composition
Sandstone Textures
Sandstone Edges
Varieties of Sandstone
SANDSTONE APPLICATION
3. Sandstone Application
• About Sandstone• Garden Sandstone• Sandstone Flooring
• Sandstone Landscaping• Sandstone Pavement• Sandstone Wall
• About Sandstone• Garden Sandstone• Sandstone Flooring
• Sandstone Landscaping• Sandstone Pavement• Sandstone Wall
SANDSTONE CHEMICAL PROPERTIES
Sandstone Chemical Properties
The chemical constitution of sandstone is the same as that of sand, the rock is thus composed essentially of quartz. The natural cementing material that binds the sand together as rock is usually composed of silica, calcium carbonate, or iron oxide. Chemically sandstone is very resistant Mono-Mineralic rock, with silica as the principal. The percentage of each constituents is as follows:SiO2 93-94%Iron (Fe2O3) 1.5%-1.6% Alumina (Al2O3) 1.4 to 1.5% Soda (Na2O) & Potash (Kro) 1.0% to 1.2% Lime (CaO) 0.8% to 0.9% Magnesia (MgO) 0.2 to 0.25% Loss On Ignition (LOI) 1.0% to 1.2%They are highly resistant to acids, alkalis and thermal impact
The chemical constitution of sandstone is the same as that of sand, the rock is thus composed essentially of quartz. The natural cementing material that binds the sand together as rock is usually composed of silica, calcium carbonate, or iron oxide. Chemically sandstone is very resistant Mono-Mineralic rock, with silica as the principal. The percentage of each constituents is as follows:SiO2 93-94%Iron (Fe2O3) 1.5%-1.6% Alumina (Al2O3) 1.4 to 1.5% Soda (Na2O) & Potash (Kro) 1.0% to 1.2% Lime (CaO) 0.8% to 0.9% Magnesia (MgO) 0.2 to 0.25% Loss On Ignition (LOI) 1.0% to 1.2%They are highly resistant to acids, alkalis and thermal impact
PEROLOGY
PETROLOGY:
The word petrology is derived from word petroleum.
Petrology is the department of science which is concerned with mineralogical & chemical compositions of rocks with their classification.
Rocks are classified mainly three groups:
· Sedimentary Rocks
· Metamorphic Rocks
· Igneous Rocks
SEDIMENTARY ROCKS:
Sedimentary rocks are formed from overburden pressure as particles of sediments are deposited out of air, ice or water flows carrying the particles in suspension. As the sediment deposition builds up, the overburden pressure (Lithostatic pressure) squeezes the sediments into layered solids. This rock formation process is known as Lithification (rock formation).
These rocks are further classified in three categories. This classification is based on three main ways of formation of sedimentary rocks:
(1) Clastic / Terrigenous / Detrital / fragmental sedimentary rocks: Clastic means broken or fragmented. Clastic rocks are composed of broken up pieces of pre-existing rocks and minerals. We can further identify these rocks based on the size of the fragments that they are composed.
PARTICLE SIZE
SEDIMENT
ROCK
Over 256 mm (10")
Boulder
Conglomerate or breccia
2 to 256mm(0.08-10")
Gravel
Conglomerate or breccia
1/16 to 2mm
Sand
Sandstone
1/256-1/16mm
Silt
Siltstone*
Less than 1/256mm
Clay
Claystone*
*also known as mudstone
(2) Biological / Bioclastic: sedimentary rocks: These sedimentary rocks are formed by the deposition of result of some biogenic activities. Coals , Cherts and shell limestone are examples of biological sedimentary rocks.
(3) Chemical sedimentary rocks : These rocks are formed by deposition of chemicals, which are generally precipitated from solutions. These rocks however, form from a water solution, and not from molten rock. Various salts (rock salt and gypsum), Dolostone, limestones are few examples of chemical sedimentary rocks. Chemical sedimentation involves water and therefore the depositional environments will be most often found near or under water.
Composition of sedimentary rocks :
Sedimentary rocks are composed of mainly silica (quartz), feldspars, amphiboles and clay material.
Note:
We are fortunate that in earth’s atmosphere, we have low levels of carbon dioxide (CO2) due to limestones and dolomite sedimentary rocks. This is a fact that most of carbon (petroleum and other hydrocarbons) on earth is trapped in limestone’s and dolomite’s layers. So less free carbon is available to react with oxygen. In this way we have low percentage of co2 on earth’s atmosphere. Making existence of life on earth possible.
METAMORPHIC ROCKS:
In a simple definition we can say that metamorphic rocks are formed from transformation of one type of natural stones to another type of natural stones through mix of heat, pressure and minerals.
These changes can be either: - Crystalline formation or/and Texture change or/and colour changeBefore understanding the metamorphic rocks, it is necessary to understand METAMORPHISM.
The word petrology is derived from word petroleum.
Petrology is the department of science which is concerned with mineralogical & chemical compositions of rocks with their classification.
Rocks are classified mainly three groups:
· Sedimentary Rocks
· Metamorphic Rocks
· Igneous Rocks
SEDIMENTARY ROCKS:
Sedimentary rocks are formed from overburden pressure as particles of sediments are deposited out of air, ice or water flows carrying the particles in suspension. As the sediment deposition builds up, the overburden pressure (Lithostatic pressure) squeezes the sediments into layered solids. This rock formation process is known as Lithification (rock formation).
These rocks are further classified in three categories. This classification is based on three main ways of formation of sedimentary rocks:
(1) Clastic / Terrigenous / Detrital / fragmental sedimentary rocks: Clastic means broken or fragmented. Clastic rocks are composed of broken up pieces of pre-existing rocks and minerals. We can further identify these rocks based on the size of the fragments that they are composed.
PARTICLE SIZE
SEDIMENT
ROCK
Over 256 mm (10")
Boulder
Conglomerate or breccia
2 to 256mm(0.08-10")
Gravel
Conglomerate or breccia
1/16 to 2mm
Sand
Sandstone
1/256-1/16mm
Silt
Siltstone*
Less than 1/256mm
Clay
Claystone*
*also known as mudstone
(2) Biological / Bioclastic: sedimentary rocks: These sedimentary rocks are formed by the deposition of result of some biogenic activities. Coals , Cherts and shell limestone are examples of biological sedimentary rocks.
(3) Chemical sedimentary rocks : These rocks are formed by deposition of chemicals, which are generally precipitated from solutions. These rocks however, form from a water solution, and not from molten rock. Various salts (rock salt and gypsum), Dolostone, limestones are few examples of chemical sedimentary rocks. Chemical sedimentation involves water and therefore the depositional environments will be most often found near or under water.
Composition of sedimentary rocks :
Sedimentary rocks are composed of mainly silica (quartz), feldspars, amphiboles and clay material.
Note:
We are fortunate that in earth’s atmosphere, we have low levels of carbon dioxide (CO2) due to limestones and dolomite sedimentary rocks. This is a fact that most of carbon (petroleum and other hydrocarbons) on earth is trapped in limestone’s and dolomite’s layers. So less free carbon is available to react with oxygen. In this way we have low percentage of co2 on earth’s atmosphere. Making existence of life on earth possible.
METAMORPHIC ROCKS:
In a simple definition we can say that metamorphic rocks are formed from transformation of one type of natural stones to another type of natural stones through mix of heat, pressure and minerals.
These changes can be either: - Crystalline formation or/and Texture change or/and colour changeBefore understanding the metamorphic rocks, it is necessary to understand METAMORPHISM.
METAMORPHISM
METAMORPHISM:
The term metamorphic is derived from the Latin term meaning, "change of form”. It can be defined as mineralogical, chemical & crystallographic changes in a solid-state rock, in response to new conditions of pressure & or temperature & or introduction of fluids, causing the existing rocks minerals to recrystalize. They may even become different minerals all together. It is important to realize that the rock remains in its solid state. Once rock minerals are melted, and then recrystallize, the new material will be igneous. Temperature change can range from 100 c to 900 c.
METAMORPHISM can be of four types:
· Regional metamorphism:
This type of metamorphism occurs in broad areas of earth’s crust. Regional metamorphism deforms the rocks strongly. This type of metamorphism is further classified in two categories Barrovian or Buchan type metamorphism depending upon temperature and pressure gradients.
· Impact metamorphism :
This type pf metamorphism occurs in ultrahigh pressures & low temperature which are the result of collision of a meteorite or extraterrestrial object or during an extremely violent volcanic eruption.
· Contact(thermal) metamorphism :
This occurs typically around igneous intrusive rocks. As a result of the temperature increase caused by igneous body itself. Magma fluids coming from the intrusive rock may also take part in contact metamorphism. Contact metamorphic rocks are known as hornfels and usually are fine grained.
· Hydrothermal metamorphism :
Hydrothermal metamorphism is the result of the interaction of a rock with high temperature fluid of distinct composition. This metamorphism results from reaction between protolith (original rock before transformation) & fluid. This kind of metamorphism is responsible for many metal deposits on earth.
We have studied metamorphism now we will be able to define metamorphism rocks more systematically.
Metamorphic Rocks results from mineralogical and structural adjustments of solid rocks to physical and chemical conditions differing from those under which the rocks originally formed. Temperature and pressure are important factor in the formation of metamorphic rocks.
Classification of Metamorphic Rocks:
Metamorphic rocks can be subdivided into foliated and non-foliated types. This is determined by the presence of minerals that are aligned parallel to each other. This results in a layered appearance. A non-foliated metamorphic rock generally consists of equal dimensional grains.
A rock can also be identified by its metamorphic grade. This is simply a description of the overall intensity of metamorphism the rock was subjected to. What this implies is that a low-grade metamorphic rock shows textural or mineralogic evidence of having been subjected to low pressures and/or temperatures.
Metamorphisms produced with increasing pressure and or temperature is known as PROGRADE METAMORPHISM. Conversely decreasing temperature and or pressure characterize RETROGRADE METAMORPHISM.
Slates, marbles & Quartzite are example of metamorphic rocks.
IGNEOUS ROCKS:
Igneous rocks are formed from solidification of molten magma erupted through the mantle or crust of earth. As this magma in earth is less dense then surrounding solid rocks, it rises up towards surface. This lava has two options depending upon it’s surrounding conditions either it may erupt at the surface from the volcano’s mouth or it may settle within the earth’s crust. This classifies the types of igneous rocks.
1. Intrusive or plutonic igneous rocks are the rocks, which results due to solidification of lava deep within earth.
2. Extrusive or volcanic rocksare the rocks, which results due to solidification or crystallization of lava on the outer surface of earth.
These two types of igneous rocks can be identified by visualizing them Since slow cooking of “intrusive rocks” promote the growth of mineral beds which can be identified without microscope. While in extrusive igneous rocks these minerals cannot be seen by naked eye. If molten magma cools at extremely high rates (as in extrusive igneous stones) disallowing crystallization, the result is a volcanic glass called obsidian.
Igneous rock textures .
Phaneritic
The size, shape and arrangement of the mineral grains of any rock is called its texture . Generally, if magma cools slowly, its mineral crystals will have more time to grow and the resulting rock will demonstrate a course or phaneritic texture. This texture will be more characteristic of intrusive rocks and you will be able to see the mineral grains .
Aphanitic
On the other hand, if the magma or lava cools quickly, the matrix of tiny crystals that are formed give the rock a fine or aphanitic texture. Fine textured rocks are usually volcanic or shallow intrusive. These rocks cool so quickly that you will usually not see the individual mineral grains with an unaided eye.
Porphyrhitic
A third type of texture occurs when a molten mass begins to cool slowly, and some crystals of one mineral begin to form. Sometimes this material is then moved (or erupted) and the remaining material cools quickly. The resulting rock will have large crystals that are in a finegrained groundmass. This is called a porphyrhitic texture, and the rock is porphyry.
Igneous rocks are also classified by the amount of silica they contain .
IGNEOUS ROCKS
ACIDIC
A ROCK THAT CONTAINS MORE THAN 66% SILICA
INTERMEDIATE
A ROCK THAT CONTAINS 52% TO 66% SILICA
BASIC
A ROCK CONTAINING 45% TO52% SILICA
ULTRABASIC
A ROCK CONTAINING LESS THAN 45% SILICA
As a rule, acidic and intermediate rocks form by the solidification of molten crystal material. Basic rocks more often form from molten material brought up from the mantle.
BY COMBINING THE TEXTURE AND THE CHEMICAL COMPOSITION OF A ROCK WE CAN DEFINE THE MOST COMMON IGNEOUS ROCKS.
COMMON IGNEOUS ROCKS
EXTRUSIVE
INTRUSIVE
ACIDIC
RHYOLITE
GRANITE
INTERMEDIATE
ANDESITE
DIORITE
BASIC
BASALT
GABBRO
ULTRABASIC
PERIDOTITE A melt goes through many stages as it solidifies in a process called fractionation. As the melt cools the minerals that generally crystallize first are those low in silica such as olivine and pyroxene. The remaining melt becomes more silica rich. This may then be erupted and form acidic rocks.
The term metamorphic is derived from the Latin term meaning, "change of form”. It can be defined as mineralogical, chemical & crystallographic changes in a solid-state rock, in response to new conditions of pressure & or temperature & or introduction of fluids, causing the existing rocks minerals to recrystalize. They may even become different minerals all together. It is important to realize that the rock remains in its solid state. Once rock minerals are melted, and then recrystallize, the new material will be igneous. Temperature change can range from 100 c to 900 c.
METAMORPHISM can be of four types:
· Regional metamorphism:
This type of metamorphism occurs in broad areas of earth’s crust. Regional metamorphism deforms the rocks strongly. This type of metamorphism is further classified in two categories Barrovian or Buchan type metamorphism depending upon temperature and pressure gradients.
· Impact metamorphism :
This type pf metamorphism occurs in ultrahigh pressures & low temperature which are the result of collision of a meteorite or extraterrestrial object or during an extremely violent volcanic eruption.
· Contact(thermal) metamorphism :
This occurs typically around igneous intrusive rocks. As a result of the temperature increase caused by igneous body itself. Magma fluids coming from the intrusive rock may also take part in contact metamorphism. Contact metamorphic rocks are known as hornfels and usually are fine grained.
· Hydrothermal metamorphism :
Hydrothermal metamorphism is the result of the interaction of a rock with high temperature fluid of distinct composition. This metamorphism results from reaction between protolith (original rock before transformation) & fluid. This kind of metamorphism is responsible for many metal deposits on earth.
We have studied metamorphism now we will be able to define metamorphism rocks more systematically.
Metamorphic Rocks results from mineralogical and structural adjustments of solid rocks to physical and chemical conditions differing from those under which the rocks originally formed. Temperature and pressure are important factor in the formation of metamorphic rocks.
Classification of Metamorphic Rocks:
Metamorphic rocks can be subdivided into foliated and non-foliated types. This is determined by the presence of minerals that are aligned parallel to each other. This results in a layered appearance. A non-foliated metamorphic rock generally consists of equal dimensional grains.
A rock can also be identified by its metamorphic grade. This is simply a description of the overall intensity of metamorphism the rock was subjected to. What this implies is that a low-grade metamorphic rock shows textural or mineralogic evidence of having been subjected to low pressures and/or temperatures.
Metamorphisms produced with increasing pressure and or temperature is known as PROGRADE METAMORPHISM. Conversely decreasing temperature and or pressure characterize RETROGRADE METAMORPHISM.
Slates, marbles & Quartzite are example of metamorphic rocks.
IGNEOUS ROCKS:
Igneous rocks are formed from solidification of molten magma erupted through the mantle or crust of earth. As this magma in earth is less dense then surrounding solid rocks, it rises up towards surface. This lava has two options depending upon it’s surrounding conditions either it may erupt at the surface from the volcano’s mouth or it may settle within the earth’s crust. This classifies the types of igneous rocks.
1. Intrusive or plutonic igneous rocks are the rocks, which results due to solidification of lava deep within earth.
2. Extrusive or volcanic rocksare the rocks, which results due to solidification or crystallization of lava on the outer surface of earth.
These two types of igneous rocks can be identified by visualizing them Since slow cooking of “intrusive rocks” promote the growth of mineral beds which can be identified without microscope. While in extrusive igneous rocks these minerals cannot be seen by naked eye. If molten magma cools at extremely high rates (as in extrusive igneous stones) disallowing crystallization, the result is a volcanic glass called obsidian.
Igneous rock textures .
Phaneritic
The size, shape and arrangement of the mineral grains of any rock is called its texture . Generally, if magma cools slowly, its mineral crystals will have more time to grow and the resulting rock will demonstrate a course or phaneritic texture. This texture will be more characteristic of intrusive rocks and you will be able to see the mineral grains .
Aphanitic
On the other hand, if the magma or lava cools quickly, the matrix of tiny crystals that are formed give the rock a fine or aphanitic texture. Fine textured rocks are usually volcanic or shallow intrusive. These rocks cool so quickly that you will usually not see the individual mineral grains with an unaided eye.
Porphyrhitic
A third type of texture occurs when a molten mass begins to cool slowly, and some crystals of one mineral begin to form. Sometimes this material is then moved (or erupted) and the remaining material cools quickly. The resulting rock will have large crystals that are in a finegrained groundmass. This is called a porphyrhitic texture, and the rock is porphyry.
Igneous rocks are also classified by the amount of silica they contain .
IGNEOUS ROCKS
ACIDIC
A ROCK THAT CONTAINS MORE THAN 66% SILICA
INTERMEDIATE
A ROCK THAT CONTAINS 52% TO 66% SILICA
BASIC
A ROCK CONTAINING 45% TO52% SILICA
ULTRABASIC
A ROCK CONTAINING LESS THAN 45% SILICA
As a rule, acidic and intermediate rocks form by the solidification of molten crystal material. Basic rocks more often form from molten material brought up from the mantle.
BY COMBINING THE TEXTURE AND THE CHEMICAL COMPOSITION OF A ROCK WE CAN DEFINE THE MOST COMMON IGNEOUS ROCKS.
COMMON IGNEOUS ROCKS
EXTRUSIVE
INTRUSIVE
ACIDIC
RHYOLITE
GRANITE
INTERMEDIATE
ANDESITE
DIORITE
BASIC
BASALT
GABBRO
ULTRABASIC
PERIDOTITE A melt goes through many stages as it solidifies in a process called fractionation. As the melt cools the minerals that generally crystallize first are those low in silica such as olivine and pyroxene. The remaining melt becomes more silica rich. This may then be erupted and form acidic rocks.
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