Charnockite Rock

Mother earth is filled with several different types of rocks. These rocks are formed due to years of suppression under the pressure applied by debris. Such rocks are called metamorphic rocks. They have been exposed to a large amount of pressure, change of season, and many earthly changes.


This process is called metamorphosis and the process is responsible for contributing to the formation of several rocks found in nature. Charnockite rock is another type of rock that is a product of metamorphosis. There are many other rocks of a similar type. A few other examples are limestone, soapstone. 


Let us take a look at the physical and chemical properties of charnockite.

Charnockite Rock Series

The Charnockite rock series consists of several naturally occurring rocks which are a product of metamorphosis. Metamorphosis is the continual process of earthly debris being exposed to harsh weather conditions and pressure. This results in the formation of rocks, many of these rocks have a highly important application in various industries.


Any orthopyroxene bearing quartz-feldspar formed at a high temperature and high pressure can be classified as a Charnockite. Charnockite is a form of granofel. Granofel is any type of rock that has a granoblastic texture. An example of a granoblastic texture is given below


The origin of charnockite is found to be in the deep crust between the tectonic plates deep into the earth’s layers of debris. The charnockite series rocks consist of rocks rich in felsic, quartz, Microcline, pyroxene, and olivine.

Properties of Charnockite Rock

  • There has been confusion about the class of charnockite rocks for a while now. Earlier, the charnockite series rocks were classified as igneous rocks. However, after some research, it was found that the charnockite series rocks are actually a variety of metamorphic rocks.

  • This conclusion was made because in spite of rising temperature the protolith did not melt. Charnockites are found in several different colors. The color depends on the composition of the rock. Each mineral has its own trademark color. The color of the charnockite series rocks can range from greasy green to aquamarine blue.

  • Often, some rocks are brownish-green as well. This color in a Charnockite rock indicates the high presence of titanium. Having a dark color and clouding of feldspars are typical features of these rocks similar to a bluish tint in quartz. The other commonly found colors include black, gray, orange, pink, and white.

  • The color also depends on the age of the rock and the amount of pressure the rock has been exposed to. The texture of the rock is generally described as coarse grainy and granoblastic. The rock directly found in nature is not soft to touch and has a pretty rough feel to it. However, when polished the rock’s texture softens.

  • Generally, charnockite is anhydrous and essentially consists of orthopyroxene as its character-defining ferromagnetic mineral along with quartz and feldspar. 


The Naming of Charnockite Rocks

As iterated earlier, charnockite rocks were earlier thought of to be igneous rocks. It was believed that charnockite rocks are formed out of crystallized magma. Hence, the charnockite rocks naming pattern follows the naming system of igneous rocks.


Some charnockite rocks do contain traces of igneous rocks as well. Hence, we can say that charnockite rocks are a mixture of minerals and igneous rocks, and other debris found in nature. 


Fun Facts About the Charnockite Rock Series

  • The charnockite rocks are still being studied. Abundant deposits of charnockite rocks are found in the Nagercoil region of Tamil Nadu. However, not every property about the charnockite rock is known clearly.

  • Also in India, they form the Nilgiri hills, the biligirirangan hills, and some parts of the western ghats. It then extends southward to Kanyakumari.

  • The composition of charnockite is diverse, it is an agglomeration of several minerals and inorganic compounds. The minerals obtained in charnockite are Amphibole, Biotite, Feldspar, Hornblade, Micas, Muscovite or Illite, Olivine, Plagioclase, Pyroxene, Quartz. 

  • The chemical compounds found in charnockite are Aluminum Oxide, CaO, Iron(III) Oxide, FeO, Potassium Oxide, MgO, MnO, Sodium Oxide, Phosphorus Pentoxide, Silicon Dioxide, Titanium Dioxide. 

  • The rock is coarse and granular in nature. The rock has no luster whatsoever, i.e. they reflect minimal light and don't have a shiny appearance. The charnockite rock is highly non-porous, which means it does not allow water to seep through it. 

  • On the Mohs Hardness scale, charnockite rock scales between 6 and 7. It implies that rocks in this range are moderately hard. 


What is the Difference Between Charnockite and Granite? 

Charnockite and granite are both types of rocks that have great utility in several industries. 


They are often confused to be the same, however, they are often confused to be the same. They have minute differences between them. Granite is an extremely hard, granular, crystalline igneous rock composed of minerals like quartz, mica, and feldspar and is mainly used as building stone.


Granites are felsic rocks and are usually pyroxene-free. Even if they contain pyroxene, they are in less diminutive amounts.  


Charnockite is normally defined as orthopyroxene granite. It is a type of granite that contains minerals such as orthopyroxene, quartz, and feldspar. In charnockite, there is a role of high pressure and temperature at birth. Charnockites are igneous while granulites are metamorphic. Charnockite is coarse-grained and lacks foliage.


Both of these have a similar utility and are often used in the construction industry.


Uses of Granite

  1. Monuments Built Using Granite: Monuments and temples that are often built to last for generations are made of granite. Before the advent of powerful cutting tools, carving granite was laborious and time-consuming. Hence, it was solely reserved for a special part of the monumental project.

  2. Granite Mantle Pieces and Staircases: Using large slabs of granite is a great way to preserve and display the beauty of the stone. Granite stones and slabs are popular due to their unique blend of beauty and practicality. Granite stairs don’t wear out for long durations of time.

  3. Granite Kitchen Worktops: Granite is extensively used for kitchen and bathroom worktops. Because of its qualities like being waterproof, stain-resistant, water-resistant, easy to clean, and hard to damage, it is the most popular choice among the audience. It is also an ideal choice to build tiled bathrooms.

  4. Granite as a Gemstone in Jewelry: There are few granites that are rare and amazingly beautiful. Since they are rare, they are turned into gemstones and used in jewelry.

  5. Granite Used to Carve out Tile Patterns: Due to the availability of natural granite in many colors, it is possible to create mosaics or tile patterns using only this stone. It ensures that no part of the patterned floor wears out.

  6. Pillar of Strength: Many ancient and historic buildings use granite to create a core of strength at their centers. Also, granite can be easily polished to a beautiful sheen or could clad into another stone, it is commonly used to build supporting pillars.

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FAQs (Frequently Asked Questions)

1. What are the uses of charnockite?

Charnockite has several utilities, it has many properties which make it highly suitable for construction. Charnockite is used in the construction of structures like roads, bridges, and buildings. They are also used in the field of pottery. They are used to make pots commonly found in the kitchen. Charnockite is also used as a gemstone to add to the home decor. It is also used to decorate the gardens.


Charnockites are still being studied. It is also believed that charnockites can also be used in the medical industry. However, this is possible only in the case of a few charnockites which have rare and exceptional properties.

2. Where is charnockite found?

Like any other rare metamorphic rock, the rocks of the charnockite series are also obtained in the earth's crust. They are mined out of the crust by digging deep. The first-ever deposit of charnockite was found in the state of Tamil Nadu in the Nagercoil district. These rocks are mainly found in the southern hemisphere.


Deposits of rocks similar to the ones obtained in Tamil Nadu are found in  Norway, France, Sweden, Germany, Scotland, and North America. A commercial variety of charnockite rocks is found in Brazil. It is called “Green Ubatuba '' and is considered a pretty rare variety of rocks.

3. What kind of rock is charnockite?

Charnockite is a series of foliated metamorphosed igneous rock of wide distribution. The charnockite series includes rocks of many different types. Some of them are acidic and rich in quartz and microcline. While others are basic and full of pyroxene and Olivine. There are also intermediate varieties corresponding, mineralogically to norites, quartz norites, and diorites. A special feature, reoccurring in many members of the group is the presence of strongly pleochroic reddish or green hypersthene.


Charnockites generally have diverse origins spanning a range of metamorphic and igneous derivation which implies that igneous or metamorphic fabric can be exhibited.

4. How did charnockite rocks get formed in the earth’s crust?

The charnockite series of rocks originally was assumed to have developed by the fractional crystallization of silicate magma (molten material). Later on, studies have shown, however, that many, if not all, of the rocks, are metamorphic. Metamorphic rocks form when rocks are subjected to high heat, high pressure, hot mineral-rich fluids, and some combination of these factors. Conditions like these are found deep within the Earth or where tectonic plates meet. Thousands of years ago, during the evolution of our planet, these conditions were prevalent naturally.

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