The name calcite comes from the Latin word “Calx” which means caustic lime. Calcite is crystallized in the trigonal system, askalnondryk class. It has large and clear crystals or in the form of granulation masses. Rombonder and skalnonder forms of calcite are more plentiful and have different and various twinning, too. The calcite structure is in the form of rombonder in which the calcium ions and the root (CO3)2- are in alternate order. In the root CO3, each carbon has been surrounded by three oxygen in a triangular form and these triangles are based on vertical planes on the C axis. This structure can be compared with the crystal network of salt in which calcium ions are in sodium positions and CO3 triangles are in the position of chloride ions.
Calcite is one of the abundant minerals of sedimentary and metamorphic rocks. Limestone, travertine and marble are only made of calcite. Some 50 percent of the marls formulation comes from calcite. A large part of calcareous sandstones are made from calcite. Calcite is formed in exterior igneous rocks at a secondary stage. The calcareous skeleton of living creatures may be made of calcite. Chalk is a kind of porous, soft and power-like lime which is produced from the calcareous shell of foraminifers. Onyx marble is a type of lime made from fine strings. Travertine is also a calcite which is formed at the site of the lime fountains. Limestone which is made of calcite along with some impurities is very abundant in Iran existing in almost all provinces.
Cao=56% Co2= 44% Mg, Fe, Mn, Ba, Pb, Zn, On
Calcite Para-geneses include dolomite, quartz, argyles, galena, and asphalrite. Calcite is widely used in the form of limestone in cement industries and lime burning plants. It is used for treatment and separation of phosphate compounds and organic acids in chemical industries such as sugar mills, and for neutralization of organic compounds and sulfides and neutralization of anhydride sulfured gas and grease production in oil industries. Calcite is used in steel mills to help melting, in paint industries as filler and in leather industries as separator of hair and wool. It is also used as putty powder in painting as well as in toothpaste, chemical wax, perfumes and tire industry. In construction industries it is used as façade slabs with the name of marmarite or travertine, porcelain slab, marble and as granule stone in preparation of concrete. The transparent type of calcite with the name of spot dissland was previously used in optical tools such as nickel for production of polarized light. Today, Polaroid sheets are used instead.