dolomite

الوصف

Crystal habit
Tabular crystals, often with curved faces, also columnar, stalactitic, granular, massive.
Crystal system
Trigonal

Twinning
Common as simple contact twins
Cleavage
Perfect on {***1}, rhombohedral cleavage
Fracture
Conchoidal
Tenacity Brittle
Mohs scale hardness 3.5 to 4
Luster
Vitreous to pearly
Streak
White
Specific gravity
2.*4–2.*6
 
 
 
Solubility
Poorly soluble in dilute HCl unless powdered.
Other characteristics May fluoresce white to pink under UV; triboluminescent.

analysis
SiO2  Al2O3  MgO  CaO  Fe2O3  TiO2      L.O.I
0.1  0.*5  *1.2  *0.4  0.*7  0.*1        *8.*7        

general
Dolomite is a carbonate mineral composed of calcium magnesium carbonate CaMg(CO3)2. The term is also used to describe the sedimentary carbonate rock dolostone.
Dolostone (dolomite rock) is composed predominantly of the mineral dolomite with a stoichiometric ratio of *0% or greater content of magnesium replacing calcium, often as a result of diagenesis.
Uses
Dolomite is used as
*- an ornamental stone,
*- a concrete aggregate,
*- a source of magnesium oxide and in the Pidgeon process
*- for the production of magnesium.
*- It is an important petroleum reservoir rock,
*- a flux for the smelting of iron and steel.
*-  Large quantities of processed dolomite are used in the production of float glass.
*- production of frit for glaze.
*-  added to soils and soilless potting mixes to lower their acidity and as a magnesium source.
**- the substrate in marine (saltwater) aquariums to help buffer changes in pH of the water.
**- one of the basic raw materials in the manufacture of flat glass, which are added by *2% as magnesium oxide helps add to the speed of the glass melting process.
**- in the manufacture of refractories due to the high melting temperature to ***0 ° C and therefore is used in the ovens foundries in Tlies containers.
**-  used in the steel industry as well as used in furnaces making steel oxygen and furnaces arcs electric –
**- is also used in furnaces smelting to reduce the melting temperature of slag