Abundance of limestone

The abundance of limestone deposits throughout the world has resulted in the use of calcium carbonate as a primary building material since antiquity. The ancient pyramids and the Sphinx in Egypt were made almost exclusively with limestone 5,000 years ago. Most limestone is used today as construction material. One estimate is that the United States used a billion tons of crushed limestone for roads, dams, fill, buildings, and various other construction uses in 2005. 

Geochemical computer modeling and the abundance of limestone indicates saturation of the groundwater with respect to anhydrite and calcite. Calcium, sulfate alkalinity, and TDS... 

In Beirut, the elemental composition study of coarse and fine particles showed that crustal elements like Si, Ca, K, Ti, Mn and Fe were prevalent in the coarse fraction while in the fine fraction S, Cu, Zn and Pb predominated. All-time high Ca concentration was due to the abundance of limestone rocks, rich in calcite, in Lebanon, and increased Cl levels correlated with marine air masses. In PM2.5, sulfur concentrations were more prominent in the summer due to the enhancement of photochemical reactions. Sources of sulfur were attributed to local, sea-water and long-range transport from Eastern Europe, with the latter being the most predominate. Anthropogenic elements like Cu and Zn were generated from worn brakes and tires in high traffic density areas. Spikes of Pb were directly linked to... 

Calcium is a metallic element, fifth in abundance in the earth s crust, of which if forms more than 3%. It is an essential constituent of leaves, bones, teeth, and shells. Never found in nature uncombined, it occurs abundantly as limestone, gypsum, and fluorite. Apatite is the fluorophosphate or chlorophosphate of calcium. 

Cave deposits consist of minerat calcite fCaCOgj that precipitate from ground-water that enters a cavern and evaporates into the air. An abundance of caicite deposits form the rock travertine (a variety of limestone). 

The outcrops of very old Archean rocks are few and thus may not be representative of the original sediment compositions deposited. Nevertheless, it appears that carbonate rocks are relatively rare in the Archean. Based on data from the limited outcrops, Veizer (1973) concluded that Archean carbonate rocks are predominantly limestones. During the early Proterozoic, the abundance of carbonates increases markedly, and for most of this Era the preserved carbonate rock mass is typified by the ubiquity of early diagenetic, and perhaps primary, dolostones (Veizer, 1973 Grotzinger and James, 2000). In the Phanerozoic, carbonates constitute 30% of the total sedimentary mass, with sandstones and shales accounting for the rest. The Phanerozoic record of carbonates will be elaborated upon in the subsequent text. 

The most abundant anion delivered by rivers to the oceans is bicarbonate ion (HCO ), and most of the bicarbonate alkalinity in rivers comes from the weathering of carbonate rocks (Meybeck, 1987). The chemical weathering of limestones and dolostones by dissolved CO2 can be represented by the reactions for dissolution of calcite and dolomite ... 

CaC03 occurs in three forms the most abundant is calcite (mineral constituent of limestone) crystallizing in the triclinic system and having a density of 2.71 g/cm. ... 

Calcium Carbonate—CaCO,—100—the most abundant of the natural compounds of Ca, exists as limestone, calcar, cheU , marble, Ice land spar, and arragonite and forms the basis of corals, shells of Crustacea and of molluscs, etc. 

---