A ubiquitous mineral found all over the world, Calcite is also a fabulous stone of extraordinary diversity and beauty as its crystals come in an endless array of gorgeous colours and shapes. It’s a soft stone characterised by fascinating properties such as double refraction, phosphorescence, thermoluminescence, and effervescence. Furthermore, the great diversity of Calcite also makes it a versatile crystal for cleansing negative energies, emotional healing and balancing all chakras.

What is Calcite?
Calcite is a carbonate mineral and is probably one of the most common minerals on this planet. It comprises almost 4% of the weight of the Earth’s crust and forms in a number of geological environments.

It is a rock-forming mineral, and is the main constituent of the three major rock classification types. In sedimentary environments it forms limestone, which in turn changes into marble due to the pressure and heat in the course of metamorphic events. And lastly, Calcite is a major component of a variety of igneous rock called Carbonatite. Some of these rocks may be composed of up to 99% Calcite.

Despite being such a common mineral across most of the globe, it is much sought after by collectors thanks to the extraordinary diversity and beauty of its crystals. This fabulous stone comes in a plethora of colours and shapes which lend themselves to beautiful jewellery and sculptures.

Characteristics of Calcite
Calcite is a transparent to opaque crystal with a Mohs hardness of merely 3, which means it is a rather soft mineral and can easily be scratched with a knife. It is usually clear or white, though due to the presence of impurities it may even be grey, orange, red, blue, violet or even black. Furthermore, Calcite displays exceptional effects such as double refraction, fluorescence and effervescence in contact with acid.

Double refraction (or birefringence) is a fascinating effect produced by Calcite’s unique optical properties. This means that when viewing into a crystal, it is possible to view two images of what stands behind a clear Calcite stone. When a ray of light enters a Calcite crystal, it is split into two: a fast and a slow beam. As the speed of the beams affects the angle of refraction of the light exiting the crystal, the beams are bent into two different angles. The clearest way to see the double refraction is placing the crystal on a printed word or a straight line (these will result into two words or two lines). This effect was first described and studied in 1669 by the Danish scientist Rasmus Bartholin. 
Other fascinating properties of Calcite are fluorescence, phosphorescence, thermoluminescence and triboluminescence, however not all crystals will display all of these properties. Some stones will fluoresce bright red, blue or purple when viewed under a UV light, while rare specimens will phosphoresce and continue glowing even after the UV source is removed. Thermoluminescence is a form of luminescence caused by previously absorbed energy from electromagnetic radiation or other ionizing radiation which is re-emitted as light upon heating the given mineral. And finally, triboluminescence is a property which should supposedly occur in most specimens, though it is not easily demonstrated: a crystal should glow if placed in a dark room and struck or put under pressure. 

Calcite will always dissolve or effervesce if it comes into contact with an acid. Just about any acid can be used, though the most effective acids for this test are vinegar or diluted hydrochloric acid. Other carbonates such as Siderite or Dolomite do not react to acids as easily as Calcite does, so this Acid Test can be used to more readily differentiate somewhat similar minerals. 

Types of Calcite 
Calcite is not only incredibly abundant and widely distributed, it is also an amazingly varied mineral which occurs in a seemingly unlimited variety of shapes and colours. Over 300 Calcite crystal forms have been identified, all of which can combine to produce thousands of different shapes and variations.  A few examples of the vast variety of Calcite gems are: Iceland Spar, which is a transparent variety with remarkable double refraction; Dogtooth Spar, with its sharp tooth-shaped crystals consisting of acute scalenohedrons; Nailhead Spar, with long and thin prismatic crystals topped by a triangular cross section which resembles a nail. 

Where can Calcite be found?
This is a ubiquitous mineral, found throughout the world in metamorphic, sedimentary and igneous rocks, consequently excellent Calcite localities are not few. Two of the classic European sites are in Germany, more specifically in St. Andreasberg in the Harz Mountains, and in Pribram in the Czech Republic.

Originally, Iceland Spar derived exclusively from the Helgustadir mine on the eastern coast of Iceland (in Reydarfjörder). This old mine was known and utilised since the 1600s and produced specimens which exhibited exceptional double refraction. This variety is currently produced in larger mines such as the Sonoran desert region in Chihuahua, Mexico, in China and in New Mexico in the USA.
Several striking varieties are found in the United States. For example, large brown to golden crystals come from the tri-state mineral region of Missouri, Kansas and Oklahoma, while high quality prismatic crystals are found in the Sweetwater Mine in Reynolds County, Missouri. Other gorgeous stones featuring a strong blue phosphorescence come from Terlingua in Brewster County, Texas, and blue Calcite clusters are found in Balmat, St Lawrence County in  New York state and finally, an orange and white variety known as Salmon Calcite, which fluoresces bright red, is mined in Ogdensburg and Franklin in Sussex County, New Jersey. These are but a handful of the localities in which outstanding Calcite stones are found. 

Calcite also occurs in the form of breathtaking formations across the world such as stalagmites and stalactites in caverns, on limestone cliffs or as a vein mineral in deposits from hot springs. Furthermore, Calcite is often also the main constituent of the shells of marine organisms such as plankton, sponges, the hard parts of red algae, brachiopods, bryozoa and oysters, to name a few. On many an occasion the Calcite in these organisms has contributed to the creation of spectacular natural formations such as the Snowy River Cave of New Mexico (USA). Here, trilobites (which have been extinct for over a quarter billion years) featuring unique compound eyes partly made of Calcite, contributed to covering the cave in a bright white variety of the mineral.

The largest ever documented single crystal of Calcite, measuring  7×7×2 m, originated from Iceland and weighed about 250 tonnes. 

Esoteric Calcite
Calcite is known to amplify and cleanse energies present in a lived-in environment. Simply placing a Calcite specimen in a room will purify it and clear it of any negative energy, remove stagnant energy and help increase the energy levels of the entire household. 

Depending on the colour and on the variety, Calcite can have a wide variety of healing actions on the body. Placed on any area of the body, any variety of Calcite can remove energy blockages, sweeping away negativity held within the auric field. 

Furthermore, every colour of Calcite can be associated to a particular chakra. Because of the incredible variety of colours, this stone will energise and heal all chakras, some crystals even resonate powerfully with more than one chakra. The Iceland Spar variety, for example, works on every Chakra, Amber Calcite is associated to the Third Eye Chakra and Shamanite Black Calcite resonates well with the Heart Chakra.

By cleansing stored negative energies in our body, all Calcite crystals can also help reduce stress and lessen fear. This stone helps ease emotional stress and replaced with serenity. It does this by calming the mind, helping to analyze a situation and stimulating the ability to have insight into a situation which will ultimately help our instincts detect which information is important at that very moment. Iceland Spar in particular is powerful in bringing hope to fearful or stressful situations. 

Calcite is thought to be a stabilising stone which increases the propensity to trust oneself and others. In the realm of relationships it is also the stone of reconciliation, thanks to its capacity to ground and centre. This fabulous stone can help maintain a balance between the people in a relationship and thus ameliorate arguments and increase communication.

It is also known to amplify the energy connected to learning abilities. It is therefore a fabulous stone for students to keep with them as it can help study more effectively and boosts memory.

Calcite is a fabulous crystal for speeding up development as well as physical, mental and spiritual growth. More specifically, it increases spiritual development, heightens our awareness of the universe, sharpens our psychic abilities and allows the soul to remember.

From an emotional and mental perspective, Calcite is a stone which can help bring inner peace by protecting, centring and grounding a person. It can be used to bring motivation and hope into one’s life, combat laziness and also become more energetic on all levels. It also helps with overcoming setbacks we encounter in our paths and encouraging us to change an idea into action. 
On a physical level, Calcite cleanses elimination organs such as the bladder, kidneys, liver or colon. Furthermore, it helps absorb calcium; it is in fact known to strengthen joints and bones. It is great support in treating intestinal and skin conditions, and also enables tissue healing and fortifies the immune system. It also increases physical strength and is often uses as an antiseptic agent or for detoxifying. 

The many uses for Calcite
The properties of Calcite make it one of the most widely used minerals. It is frequently used to make gorgeous jewellery and beautiful ornaments but has many other uses too. It is, for example, used as an agricultural soil treatment, construction aggregate, as an abrasive, a construction material, a pigment, in pharmaceuticals and much more.

For instance, Calcite is used as a neutraliser of acids in many industries. Marbles and Limestones have, for centuries, been pulverised and spread on fields to treat the soil and offset excessive acid. In the chemical industry crushed limestone is scattered into streams which are plagued with acid mine drainage in order to neutralise their waters. Furthermore, the calcium carbonate derived from limestones or marbles is used as a  key ingredient in medicines used to nullify stomach acids and to treat digestive ailments.

Limestone is often treated to be used as a sorbent to ‘capture’ other substances during the burning of fossil fuels. Reacting with sulphur dioxide and other gases in combustion emissions, Calcite absorbs them, preventing their escape into the atmosphere.
For millennia, marble has been used to create gorgeous sculptures and grandiose monuments. Its low hardness makes it an easy stone to cut and chisel, while its relative lack of porosity allow it to cope well with the elements. 

In pulverised form, Calcite can be used as a dietary supplement in animal feed. Minute amounts of Calcium Carbonate are added to animal feed in order to increase their calcium intake. It is most commonly added to fodder for chicken, to support their production of eggs, and for cows that produce milk. Powdered Calcite has also long been used as a ‘whiting’ or white pigment. Due to its extremely white colour, once in powdered form it is used as the primary ingredient in whitewash and some early paints used Calcite too. A further use of pulverised limestone is found in the mining industry. As this Calcite-based dust is non-flammable, it is sprayed onto the roofs and walls of underground coal mines to reduce coal dust in the mine. As the Calcite adheres to the walls, it immobilises the coal particles. These would otherwise be floating in the air constituting an explosion hazard. Moreover, Calcite’s white colour functions as an aid to the illumination in the mine, making it  the perfect material for this use.