Calcite

Calcite

Calcite is one of the most prevalent minerals on earth. It can be found distributed throughout the earth on almost every continent. It is so prevalent that it makes up approximately 4 percent of the weight of earth's crust. Calcite also forms the basis of many rocks such as limestone and is the glue that holds together sandstone and shale.(Amethyst Galleries' Mineral Gallery)

Calcite is part of the carbonate group of minerals. Carbonates consist mainly of carbon as the name would imply and oxygen. Calcite or calcium carbonate, is made up of calcium, carbon and oxygen. The chemical formula of calcite is Ca(CO3) meaning that the molecule of calcite consists of one atom each of calcium and carbon and three atoms of oxygen. This compound makes it easy for it to be broken down or dissolved by even weak acids. The hydrogen in the acid bonds with oxygen in the calcite to make water and the remaining carbon and oxygen combine to make carbon dioxide while the calcium dissolves in the water and is washed away. This chemical reaction makes calcite very easy to distinguish because by simply pouring household vinegar on it will make it fizz and bubble. (Mindat.org,Earth Science)

Calcite in its pure crystalline form is a transparent or translucent mineral that can be in a wide variety of shapes from hexagonal to rhombohedral among others. It is a very soft mineral which can usually be crushed by hand. Since calcite is basically chalk the streak test for it turns out white. Calcite is also fluorescent under ultraviolet light. The that it fluoresces varies depending on geographical location and the impurities contained within the crystal. Some varieties are even phosphorescent, meaning they glow in the dark. (The Mineral and Gemstone Kingdom)

Calcite can be found in many instances and forms throughout the world. Calcite is produced by sea creatures for their shells and it also makes up coral reefs. Sea creatures take carbon dioxide that has dissolved in the ocean and combine it with calcium to make calcite. This process is also helpful to the environment as it takes carbon dioxide out of the air and thus reducing greenhouse gasses. (Amethyst Galleries' Mineral Gallery)

Another interesting formation of calcite is in caves. The stalactites and stalagmites in caves are formed when calcite in the surrounding rock is dissolved by slightly acidic ground water which then seeps into caves