What is Aurora Calcite?

Calcite is a carbonate mineral and the primary component of the sedimentary rock called limestone. It is one of the most common minerals found on Earth and is a major component of the Earth's crust. Here are some key characteristics that define calcite as a type of stone:

• Chemical Composition: Calcite is composed of calcium carbonate (CaCO3), which is a common compound found in many parts of the Earth's crust.
• Crystal Structure: Calcite has a trigonal (rhombohedral) crystal system, which means its crystals can form rhombohedral shapes, often with a hexagonal cross-section.
• Hardness: Calcite has a Mohs hardness of 3, which means it can be easily scratched by a steel knife or a copper coin.
• Cleavage: It has perfect rhombohedral cleavage, which allows it to break into rhombohedral-shaped fragments.
• Luster: Calcite typically exhibits a vitreous (glass-like) luster.
• Streak: The streak of calcite is white, which is the color of the powder produced when the mineral is dragged across an unweathered surface.
• Optical Properties: Calcite is birefringent, meaning it has the property of double refraction, which causes a single light beam to split into two distinct rays when passing through the crystal.
• Color: Calcite can be colorless, white, or have a variety of colors due to impurities, including yellow, green, blue, pink, red, and gray.
• Formation: Calcite is formed in a variety of geological settings, including marine environments where it precipitates from seawater, in caves as stalactites and stalagmites, and in metamorphic rocks.
• Uses: Calcite is used in many industries, including construction, as a component of cement, in the production of lime for agriculture and construction, and in the manufacture of glass and steel.

In summary, calcite is a versatile and abundant mineral that plays a significant role in the geological and industrial aspects of our planet.

Why does calcite look like crystal?

The reason why calcite looks transparent and resembles crystal is mainly related to its physical properties and crystal structure:

1. Crystal structure: The crystal structure of calcite allows light to pass through, similar to the crystal structure of quartz (crystal), both of which allow light to propagate internally, thus presenting a transparent or translucent appearance.
2. Refractive index: Calcite has a relatively low refractive index, which means that light refracts and reflects less when passing through calcite, thus maintaining a higher level of transparency.
3. Birefringence: Calcite has birefringent properties, meaning that when light passes through calcite, it is split into two polarized rays. This phenomenon can increase the transparency and luster of calcite when observed at certain angles, making it look more like crystal.
4. Purity: Pure calcite contains little or no impurities, which reduces the scattering of light within the crystal, allowing calcite to transmit light more clearly, thus appearing more transparent.
5. Polishing and cutting: High-quality calcite crystals, after careful cutting and polishing, have smooth surfaces that can better reflect and refract light, enhancing their transparent effect.
6. Color: Colorless or light-colored calcite crystals are more likely to appear transparent because darker minerals usually absorb more light, reducing transparency.
7. Crystal size and shape: Larger calcite crystals, if free of obvious cracks or inclusions, usually appear more transparent.

                            Quartz molecular structure

Calcite molecular structure

Although calcite and crystal may look similar in appearance, they differ in chemical composition, hardness, density, and other aspects. Calcite has a lower hardness and is more easily scratched, while quartz (crystal) has a higher hardness and is more resistant to wear. In addition, the specific gravity of calcite is lighter than that of crystal. These differences make the two minerals different in practical applications and value.

Reference

1.  "Calcite Quarry, Michigan". Earth observatory. 7 August 2006. Retrieved 17 February 2023.

2. ^ Hudson Institute of Mineralogy. "Calcite from Canada". mindat.org. Retrieved 17 February 2023.

3. ^ Hudson Institute of Mineralogy. "Santa Eulalia Mining District, Aquiles Serdán Municipality, Chihuahua, Mexico". mindat.org. Retrieved 17 February 2023.

4. ^ Jump up to:^a b c AZoMining (15 October 2013). "Calcite – occurrence, properties, and distribution". azomining.com. Retrieved 17 February 2023.