— April 17, 2023
Limestone and dolomite are carbonate sedimentary rocks generally formed in marine settings from the precipitation of calcium in seawater, often via biological processes. Limestones are rich in the calcium carbonate minerals aragonite and calcite, while dolomite contains the mineral dolomite (CaMg(CO3)2). These rocks may preserve fossils, helping geologists to determine the age of carbonate-containing formations. The porosity of some carbonate rocks can make them efficient petroleum reservoirs. Carbonate rocks are also excellent hosts for some types of ore deposits, such as Mississippi Valley Type lead-zinc deposits.
Limestone has many industrial uses including aggregate, cement manufacturing, metallurgical fluxes in the production of steel and other metals, soil conditioners, pigments, fillers, and chemical feedstock. The reactivity of limestone with acids makes it useful in scrubbers in industrial plants that produce acidic fumes that would otherwise escape into the environment. The antacid, Tums, and toothpaste are two household products that contain calcium carbonate sourced from limestone. Dolomite can be a source of magnesium and has similar uses to limestone. Magnesium, a critical mineral, is used in batteries as well as high-strength alloys and other applications. In some metallurgical applications, dolomite is a more useful flux because the slag that is produced becomes a stronger aggregate than that made by limestone.
New Mexico contains abundant limestone and dolomite. For example, the Guadalupe Mountains near Carlsbad expose the Permian Capitan Reef, consisting of carbonates deposited by sponges and algae, as well as other fossils of ammonites, crinoids, bivalves, brachiopods, and even the occasional trilobite. Dissolution of carbonate rocks by acidic fluids, such as carbonic or sulfuric acid in water, can form spectacular caves, such as those at Carlsbad Caverns.
— Evan Owen, Economic Geologist, NMBGMR