Ferrous iron commonly substitutes for some of the magnesium in dolomite, and a complete series very likely extends between dolomite and ankerite [∼CaFe(CO3)2]. Manganese also substitutes for magnesium, but typically only to the extent of a few percent and in most cases only along with iron. Other cations known to substitute—albeit in only relatively minor amounts—within the dolomite structure are barium and lead for calcium and zinc and cobalt for magnesium.
- Dolomite makes up approximately 2 percent of the Earth’s crust. The bulk of the dolomite constitutes dolostone formations that occur as thick units of great areal extent in many sequences of chiefly marine strata. (The rock dolostone is referred to by only the mineral name—i.e. dolomite—by many geologists.)
- Dolomite as a mineral has very few uses. However dolostone has an enormous number of uses because it occurs in deposits that are large enough to mine
USES OF DOLOMITE
The most common use for dolostone is in the construction industry. It is crushed and sized for use as a road base material, an aggregate in concrete and asphalt, railroad ballast, rip-rap or fill.
It is also calcined in the production of cement and cut into blocks of specific size known as “dimension stone”
Dolomite’s reaction with acid also makes it useful. It is used for acid neutralization in the chemical industry, in stream restoration projects and as a soil conditioner. Dolomite is used as a source of magnesia (MgO), a feed additive for livestock, a sintering agent and flux in metal processing and as an ingredient in the production of glass, bricks and ceramics. Dolomite serves as the host rock for many lead, zinc and copper deposits. These deposits form when hot, acidic hydrothermal solutions move upward from depth through a fracture system that encounters a dolomitic rock unit. These solutions react with the dolomite which causes a drop in pH that triggers the precipitation of metals from solution. Dolomite also serves as an oil and gas reservoir rock. During the conversion of calcite to dolomite a volume reduction occurs. This can produce pore spaces in the rock that can be filled with oil or natural gas that migrate in as they are released from other rock units. This makes the dolomite a reservoir rock and a target of oil and gas drilling.