About Calcite

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Keep reading to discover more about calcite

• Mineralogy and geology*
• Metaphysical, Spiritual and Healing** Properties***
• Common Associations

Mineralogy and Geology of Calcite

Mineral formula: CaCO₃

Mineral group: the Calcite Group

Crystal system: trigonal

Crystal habit: Over 800 different forms of calcite crystals have been described. Most commonly it occurs as acute rhombohedrons or prismatic with scalenohedral terminations, or combinations of the two.

Cleavage: perfect on {1011}

Fracture: conchoidal

Color: white, colorless, yellow, red, orange, blue, green, etc.

Luster: vitreous, sub-vitreous, resinous, waxy, pearly

Diaphaneity: transparent, translucent

Moh’s scale hardness: 3

Streak: white

Specific gravity: 2.7102

Named after:  Named as a mineral by Gaius Plinius Secundus (Pliny the elder) in AD 79 from calx, Latin for lime

Geological occurrence:  One of the most ubiquitous of minerals, calcite is found in most geologic settings and as a later forming replacement mineral in most other environments in one form or another. It is most common as massive material in limestones and marbles. It forms in chemical sedimentary deposits as limestone, can be regionally or contact metamorphosed into marbles, and also (rarely) forms igneous rocks (carbonatites). Calcite is a common gangue mineral in hydrothermal deposits.

Calcite is the most common form of crystalline CaCO₃, and one of the most common minerals on Earth’s crust; it is the dominant component of the sedimentary rock limestone. The White Cliffs of Dover are perhaps the most famous sequence of marine limestones in the western world; they consist of trillions and trillions of coccoliths, the shells of a type of marine algae (a species of eukaryote phytoplankton) that died in the oceans during the late Cretaceous, about 135 million years ago. Chalk is made of the same limestone.

Most of us are familiar with calcite as a component of concrete and cement, perfected in Roman times, using baked limestone as the source for lime, CaO.

The second most abundant form of CaCO₃ is aragonite, found in the shells of both marine and fresh water shelled creatures. The crystalline structure of aragonite is different from calcite, and relatively unstable, converting to calcite with time, pressure and/or heat. 

Geological Formation of Calcite 

Most calcite starts off as CaCO₃ in the form of aragonite in the shells of marine and freshwater organisms. Crystallization of CaCO₃ is favored by warm water (that’s why your hot water heater accumulates “scale”) so most of the micro-critters that secrete CaCO₃ are plankton (floaters) such as coccoliths and foraminifera. Other organisms that secrete CaCO₃include red algae, and some sponges, echinoderms, bryozoa and bivalves.

Trilobites, one of the dominant marine organisms of the early Cambrian Period (about 520 mya) through the early Devonian, used lenses of clear calcite crystals as part of their eyes. 

Many of the world’s most spectacular caves are found in limestone terrain, attesting to the solubility of calcium carbonate. Features such as stalactites and stalagmites are found there; their formation may be partially attributed to microorganisms secreting CaCO₃.

In hot springs, a combination of inorganic and organic (microbially-mediated) deposition of calcium carbonate results in deposits of calcareous sinter and travertine.

When carbonate-rich sedimentary rocks are buried and metamorphosed, the calcium carbonate can be transformed into the rock type marble, where the calcite crystals are larger and interlocking. The calcite can also be dissolved in aqueous solutions and injected as vein material through metamorphism and volcanism.

Calcite also occurs in igneous rocks. In relatively low temperature hydrothermal deposits (such as pegmatites) it can precipitate in veins and in geodes. Many spectacular amethyst geodes from Brazil often have calcite crystals growing on a bed of amethyst. Rare volcanoes erupt calcium carbonate-rich magma (carbonatites) and it has been found in volcanic rocks thought to be of mantle origin (kimberlites and peridotites). 

Uses of Calcite

• Calcite, in the form of marble and “alabaster” has been used since ancient times for carving statues and figurines due to its softness (3 on Moh’s scale of hardness).
• Optically clear calcite (such as Iceland spar) has been used in various optical applications. In World War II it was used for gun sights. It has been used as a polarizing device in microscopes.
• Calcite is often used as an abrasive; the brand Bon Ami is 100% calcite, much softer than quartz-based abrasive cleaners.
• Microbially precipitated calcite is finding new applications in environmental remediation.
• Calcite / limestone is often used as a soil conditioner in agriculture.
• The world’s most used construction material, concrete, typically uses some type of lime-based cement as a major component. Lime (CaO) is made by burning limestone; this is called “quick lime,” which is typically then slaked with water forming CaOH (calcium hydroxide).

Calcite Trivia

• Alabaster, a term sometimes used by non-geologists for fine-grained massive calcite (limestone), originates from the root word Bast – carvings of the Egyptian cat goddess were often carved from marble.
• The world’s biggest calcite mine is the Calcite Quarry in Michigan, in use for over 85 years.
• The form of optically clear calcite called “Iceland Spar” was mined from the Helgustadir Mine in eastern Iceland. The mine was active from the 1700’s to the 20^th century and produced most of the optically clear calcite now found in museums. Collecting is no longer permitted.
• The largest documented calcite crystal is from Iceland; it measured about 23 ft x 23 ft x 7 ft and weighed about 250 ton

Spiritual, Metaphysical and Healing Properties

Calcite is an energy amplifier, and uniquely associated with the mind, helping with memory and clarity. Clear and white calcite in particular help to clear and activate all the chakras. Used with intention, calcite is an energy amplifier.

When used with crystal grids, calcite acts as a seeker crystal, assisting with manifesting goals and desires, attracting that which is needed. 

Clear calcite assists with cleansing and aligning all the chakras (energy centers) of the body, allowing for new beginnings.

Yellow/gold calcite assists with mental discernment and alertness, and is uplifting and expansive.

Pink calcite (also called mangan, or mangano, calcite) assists clearing of the heart chakra, releasing fear and grief, and allowing for forgiveness and self-acceptance.

Common Associations

• Chakra – depends on color
• Clear / white – third eye and crown
• Black – root
• Blue – throat and third eye
• Brown – sacral and root
• Golden / yellow – solar plexus; golden for crown
• Green – heart
• Orange – sacral
• Pink (mangano calcite) - heart
• Numerology - vibrates to the number 8
• Zodiac – Cancer
• Bagua area – depends on color
• Family & new beginnings (zhen) – green, blue calcite
• Wealth & abundance (xun)
• Center & healing (tai qi) – yellow, orange, brown, gold
• Children & completion (dui) – white, clear
• Love & partnerships (kun) - pink
• Birthstone – no traditional, but great for those born in the sign of Cancer (July)
• Wedding Anniversary – no traditional

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* Mineralogical information is from mindat.org

** Always consult with your medical professional for any physical or long-term healing issues.

*** Metaphysical properties come from: 

Love Is in the Earth (1995) Melody, Earth-Love Publishing House, 726 pp.

The Crystal Bible, A Definitive Guide to Crystals (2003) Judy Hall, Walking Stick Press, 399 pp.

Crystal Muse (2017) Heather Askinosie and Timmi Jandro, Hay House, 285 pp.

Crystal Gridwork (2018) Kiera Fogg, Weiser Books, 128 pp.