Calcite
Calcite — Many Colours and Strong Double Refraction
Calcite is a very common crystal in the carbonate family, composed of calcium carbonate — CaCO₃. It occurs in nature as colourless or white material and in other colours including yellow, orange, pink, green and blue.
A transparent calcite crystal can sometimes show an interesting effect: when placed over a page of text and viewed through, the letters appear doubled. This happens because the crystal splits light into two rays — a phenomenon called double refraction.
Gemological Properties
| Mineral | Calcite |
|---|---|
| Chemical composition | Calcium carbonate — CaCO₃ |
| Colour | Colourless, white and many other colours |
| Mohs hardness | 3 |
| Refractive indices | Approximately 1.486 and 1.658 |
| Birefringence | Approximately 0.172 |
| Specific gravity | Approximately 2.71 |
| Crystal system | Trigonal |
| Transparency | Transparent to opaque |
| Cleavage | Perfect in three directions |
| Lustre | Vitreous, sometimes pearly on cleavage surfaces |
Double Refraction — Why Does the Image Appear Doubled?
When light passes through calcite in a suitable direction, it splits into two rays that behave differently inside the crystal. The large difference between their refractive indices allows two separate images to be seen through a transparent crystal.
The effect depends on transparency, crystal thickness and viewing direction. It is therefore not equally visible in every calcite specimen.
Calcite in Rocks and Caves
Calcite is a major constituent of limestone and marble and also occurs in mineral veins and cave deposits. It can occur as crystals of various shapes or as compact aggregates.
Calcite, Aragonite and Onyx Marble
Calcite and aragonite share the same principal chemical composition — CaCO₃ — but have different crystal structures, making them separate minerals.
The trade name onyx marble is used for banded carbonate material that can contain calcite and aragonite. It should not be confused with onyx in the chalcedony family, whose principal composition is SiO₂.
Sensitivity and Care
Calcite is relatively soft and has perfect cleavage, so it scratches and suffers damage easily. Protect it from impacts, pressure and abrasion.
It is sensitive to acids. Do not clean it with vinegar, lemon juice or acidic cleaners. For gentle cleaning, use a soft cloth and, if needed, a little water and mild soap without vigorous rubbing. Avoid steam and ultrasonic cleaning.
Sources Around the World
Calcite is abundant worldwide. Familiar crystal localities include Iceland, Mexico, the United States and Namibia. An occurrence in a particular area does not guarantee a specific colour or transparency.
Spiritual and Symbolic Meaning — Beliefs and Traditions
The name comes from the Latin word calx, meaning lime.
Calcite aids processes of change by ridding oneself of beliefs and thought patterns that no longer serve him.
Placing it on a painful place can ease the pain, especially in cases of joint pain, cartilage problems, fractures and swelling. It is excellent for arthritis, and as a cooling stone, is suitable for treating infections, fever and burns.
It is recommended for people who treat skeletal problems such as physiotherapists, physiotherapists, and Alexander method therapists.
Calcite features by color:
Green : best suited for skeletal problems - with joints, bones and cartilage..
Blue calcite: helps interpret symbols in meditations and dreams, and may help remember dreams.
Opaque pink calcite, Mangano calcite : works on the heart, helps one to open up emotionally and connects self-love with the love that reaches out to external things.
Pink calcite: enables looking into one’s heart to help one’s emotional development.
Yellow calcite: helps raise low self-worth. It is also helpful in dealing with cases of nausea.
Orange calcite: energetically addresses issues of sexuality and creation. It encourages changes related to fertility, sexuality and sensuality.
Honey-colored calcite: used to help with gastrointestinal problems as a result of difficult life changes.
Transparent-white rhombus calcite: when asking questions of the higher self in meditation, it can help one can receive answers from the higher parts of his awareness.
Onyx-marble: not real onyx, but rather calcite mixed with aragonite. This stone is particularly suitable for those experiencing difficulties and storms of emotion during times of significant change.
These meanings belong to the realm of belief and symbolism. They can give jewellery personal significance, but they are not proven gemological properties or a promise of healing, protection or a change in health.
