AR
-
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 nearly 2 percent of the Earth's crust. The majority of dolomite forms dolostone formations, which occur as thick units with extensive lateral extent in many marine sedimentary sequences primarily. (The rock dolostone is commonly referred to by its mineral name only - dolomite - by many geologists.)
-
Dolomite as a mineral has very few uses. However, dolostone has a vast number of applications because it occurs in large enough deposits to be mined.
Uses of Dolomite
It is crushed and sized for use as a basic material for roads, aggregate in concrete and asphalt, railroad ballast, or riprap.
Also, it is calcined in cement production and cut into blocks of specific size known as "dimension stone."
Furthermore, dolomite's reaction with acid makes it useful. It is used to neutralize acid in the chemical industry, and in stream restoration projects and as a soil conditioner. Dolomite serves as a source of magnesium oxide (MgO), an additive in livestock feed, and a flux and flow agent in mineral processing and as a component in glass, brick, and ceramic production. Dolomite is considered 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 encountering a dolomite rock unit. These solutions react with the dolomite causing a decrease in pH, leading to the deposition of metals from the solution. Additionally, dolomite acts as a reservoir for oil and gas. During the conversion of calcite to dolomite, a volume decrease occurs. This can create porous spaces in the rock that can be filled with oil or natural gas migrating to it from other rock units upon release. This makes dolomite a reservoir rock and a target for oil and gas exploration.
