Calcite Mineral
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A Calcite Mineral is a carbonaete crystalline mineral that consists primarily of calcium carbonate (CaCO₃) and crystallizes in the trigonal crystal system.
- AKA: CaCO3.
- Context:
- It can have a trigonal crystal system and can occur in various crystal habits including scalenohedra, rhombohedra, and prisms.
- It can (typically) have a Mohs hardness of 3, which makes it relatively soft and easily scratched by a metal blade.
- It can range from being transparent to opaque.
- It can exhibit various colors depending on the presence of impurities.
- It can have a high birefringence, and when a clear calcite crystal is placed over an image or text, it will create a double image, a property known as double refraction.
- It can reacts with acid, causing it to effervesce.
- It can be an abundant mineral found in a wide variety of geologic settings, from sedimentary rocks like limestone, which is composed primarily of calcite, to metamorphic rocks, and in hydrothermal veins.
- It can be a common constituent of fossil shells and stalactites and stalagmites in caves.
- It can be used in the production of cement, as a flux in steelmaking, in agricultural soil treatment, and more.
- …
- Example(s):
- Iceland Spar, a clear and transparent variety of calcite known for its strong birefringence.
- Travertine, a variety of calcite deposited from hot springs or cave systems.
- Tufa, a porous form of calcite often deposited in freshwater environments.
- Dogtooth Spar, a scalenohedral crystal variety often found in caves or hydrothermal deposits.
- Marble, a metamorphic rock composed predominantly of recrystallized calcite.
- ...
- Counter-Example(s):
- Aragonite, a polymorph of calcium carbonate with a different crystal system (orthorhombic).
- Dolomite, a related carbonate mineral containing magnesium in addition to calcium.
- Quartz, a silicate mineral that does not effervesce with acid and has a different crystal system.
- Gypsum, a sulfate mineral often confused with calcite but with different chemical and physical properties.
- See: Carbonate Mineral, Limestone, Marble, Calcium Carbonate, Crystal System, Mohs Hardness, Birefringence, Acid, Fossil, Stalactite, Stalagmite, Vaterite, Peridotite, Polymorphism (Materials Science).
References
2021
- (Wikipedia, 2021) ⇒ https://en.wikipedia.org/wiki/Calcite Retrieved:2021-8-14.
- Calcite is a carbonate mineral and the most stable polymorph of calcium carbonate (CaCO3). The Mohs scale of mineral hardness, based on scratch hardness comparison, defines value 3 as "calcite". Other polymorphs of calcium carbonate are the minerals aragonite and vaterite. Aragonite will change to calcite over timescales of days or less at temperatures exceeding 300 °C, and vaterite is even less stable.