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What is Calcite?

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Calcite mineral forms rocks and has the chemical formula CaCO3. It is extremely common and can be found in sedimentary, metamorphic, and igneous rocks all over the world. Some geologists consider it a "ubiquitous mineral," meaning it can be found anywhere.


Calcite is the main component of limestone and marble. These rocks are extremely common and account for a sizable portion of the Earth's crust. They are one of the world's largest carbon repositories.


Calcite Mineral- Natural Occurrence

Calcite is a common constituent of sedimentary rocks, particularly limestone, which is formed primarily from the shells of dead marine organisms. Limestone makes up about 10% of sedimentary rock. It is the main mineral found in metamorphic marble. It can also be found as a vein mineral in hot spring deposits, as stalactites and stalagmites in caverns, and in volcanic or mantle-derived rocks such as carbonatites, kimberlites, and, in rare cases, peridotites.


Calcite is a primary constituent of the shells of many marine organisms, including plankton (such as coccoliths and planktic foraminifera), the hard parts of red algae, some sponges, brachiopods, echinoderms, some serpulids, most bryozoa, and parts of some bivalves' shells (such as oysters and rudists). 


Calcite can be found in spectacular form in New Mexico's Snowy River Cave, where microorganisms are credited with natural formations. Trilobites, which went extinct a quarter billion years ago, had compound eyes with lenses made of clear calcite crystals.


Calcite Formation Process

Calcite formation can occur via a variety of mechanisms, ranging from the classical terrace ledge kink model to the crystallisation of poorly ordered precursor phases (amorphous calcium carbonate, ACC) via an Ostwald ripening process or nanocrystal agglomeration.


Acc Crystallisation Can Take Place in Two Stages: 

First, the ACC nanoparticles rapidly dehydrate and crystallise to form individual vaterite particles. Second, the vaterite undergoes a dissolution and reprecipitation mechanism, with the reaction rate controlled by the calcite surface area. The second stage of the reaction occurs at a rate that is approximately ten times slower. Calcite crystallisation, on the other hand, has been found to be pH-dependent and Mg-dependent in solution. 


During mixing, a neutral starting pH promotes the direct transformation of ACC into calcite. When ACC forms in a solution with a basic initial pH, it transforms to calcite via metastable vaterite, which forms via a spherulitic growth mechanism. A surface-controlled dissolution and recrystallization mechanism transforms vaterite to calcite in a second stage. Mg has a significant effect on the stability of ACC as well as its transformation to crystalline CaCO3, resulting in the formation of calcite directly from ACC.


What is Calcite Chemical Formula?

Calcite Formula: CaCO3 

Calcite Chemical name: Calcium Carbonate


Calcite Mineral- Physical Properties

Physical Properties of Calcite

Chemical Classification

Carbonate

Colour

Usually white but also colourless, grey, red, green, blue, yellow, brown, orange

Streak

White

Lustre

Vitreous

Diaphaneity

Transparent to translucent

Cleavage

Perfect, rhombohedral, three directions

Mohs Hardness

3

Specific Gravity

2.7

Diagnostic Properties

Rhombohedral cleavage, powdered form effervesces weakly in dilute HCl, curved crystal faces and frequent twinning

Crystal System

Hexagonal


Calcite Uses

Calcite crystal’s properties make it one of the most widely used minerals. It is used as a building material, abrasive, agricultural soil treatment, construction aggregate, pigment, pharmaceutical, and other applications. It has more applications than nearly any other mineral.


Calcite as Limestone and Marble

Limestone is a sedimentary rock that is primarily composed of calcite. During diagenesis, it is formed by both the chemical precipitation of calcium carbonate and the transformation of shell, coral, faecal, and algal debris into calcite. Limestone is also formed as a deposit in caves as a result of calcium carbonate precipitation.


Marble is a metamorphic rock formed when limestone is heated and pressed. A close examination of a broken piece of marble will usually reveal visible calcite cleavage faces. The degree of metamorphism determines the size of the calcite crystals. Larger calcite crystals are found in marble that has been subjected to higher levels of metamorphism.


Calcite in Construction

Calcite in the form of limestone and marble is primarily consumed by the construction industry. For thousands of years, these rocks have been used as dimension stones and in mortar. Many of Egypt's and Latin America's pyramids were built with limestone blocks as the primary building material. Today, rough and polished limestone and marble are still popular materials in high-end architecture.


Calcite in the form of limestone and marble is used in modern construction to make cement and concrete. These materials are easily mixed, transported, and placed as a slurry, which hardens into a durable construction material. Concrete is used in the construction of buildings, highways, bridges, walls, and a variety of other structures.


Calcite Mineral in Acid Neutralization

Calcite has a wide range of applications as an acid neutralizer. Limestones and marbles have been crushed and spread on fields for hundreds of years as an acid-neutralizing soil treatment. They are also heated in order to create lime, which has a much faster reaction rate in the soil.


In the chemical industry, calcite is used as an acid neutralizer. Crushed limestone is dispensed into streams to neutralise their waters in areas where acid mine drainage is a problem.


In medicine, calcium carbonate derived from high-purity limestones or marbles is used. Calcium carbonate is mixed with sugar and flavouring to make chewable tablets that are used to neutralise stomach acids. It is also found in a variety of medications used to treat digestive and other ailments.


Calcium Carbonate Sorbents

Sorbents are substances that can "capture" or "retain" another substance. Limestone is frequently treated and used as a sorbent material in the combustion of fossil fuels. Calcium carbonate reacts with sulphur dioxide and other gases released by combustion, absorbs them, and prevents them from escaping into the atmosphere.


Monuments and Statuary

Marble is a beautiful and easy-to-work-with stone that has long been used for monuments and sculptures. Its lack of significant porosity allows it to withstand freeze-thaw action in the outdoors, and its low hardness makes it a simple stone to work with. It has been used in projects ranging from the pyramids to a figurine. It is widely used in the construction of cemetery markers, statues, mantles, benches, stairways, and other structures.


Many Other Uses

Calcite has an extremely white colour when powdered. Calcite powder is frequently used as a white pigment or "whiting." Calcite was used in some of the first paints. It is a primary component of whitewash and is used as an inert colouring agent in paint.


Animal feed frequently contains pulverised limestone and marble as a dietary supplement. Cattle that produce milk and chickens that produce eggs require a calcium-rich diet. To increase calcium intake, small amounts of calcium carbonate are frequently added to their feeds.

FAQ (Frequently Asked Questions)

Q1. What is Calcite Believed to Be Good for?

Ans. Calcite, also known as the emotional intelligence stone, has an uncanny ability to create a clear and harmonious bridge of awareness between your emotions and your intellect. Calcite is said to bring wise energy, allowing one to make timely decisions without feeling rushed.

Q2. How to Care for Calcite?

Ans. Calcite is easily scratched and, like most carbonates, is acid sensitive. As a result, avoid using harsh cleaning agents such as bleach and acid. When caring for your calcite, avoid using ultrasonic cleaners or steamers. When cleaning your stones, use only a soft cloth and, if necessary, a mild soap.