- published: 17 Oct 2013
- views: 9677
Calcite is a carbonate mineral and the most stable polymorph of calcium carbonate (CaCO3). The other polymorphs are the minerals aragonite and vaterite. Aragonite will change to calcite at 380-470°C, and vaterite is even less stable.[citation needed]
Calcite crystals are trigonal-rhombohedral, though actual calcite rhombohedra are rare as natural crystals. However, they show a remarkable variety of habits including acute to obtuse rhombohedra, tabular forms, prisms, or various scalenohedra. Calcite exhibits several twinning types adding to the variety of observed forms. It may occur as fibrous, granular, lamellar, or compact. Cleavage is usually in three directions parallel to the rhombohedron form. Its fracture is conchoidal, but difficult to obtain.
It has a defining Mohs hardness of 3, a specific gravity of 2.71, and its luster is vitreous in crystallized varieties. Color is white or none, though shades of gray, red, orange, yellow, green, blue, violet, brown, or even black can occur when the mineral is charged with impurities.
Calcite: The Miracle Mineral of the History of Polarization
Calcite - The different types and its different uses
Orange Calcite Lets Talk Stones
Ask-a-Geologist #14: What are the properties of the mineral calcite?
Calcite's Reaction to Hydrochloric Acid.m2t
GOLD !!!! In Calcite Crystals
Identifying Calcite
More! Plaque calcite removal extraction (tartar)
Why Rose Quartz, Blue Calcite & Blue Lace Agate are the New Black
Calcite Crystals near Ottawa (Rocks and Minerals)
The trees are grey here
The soil is damp and cold
His senses are filled with drought
After his flee from the temple
Rites made him shiver from fear
Now waiting for someone
To proclaim salvation