Limestone is typically a sedimentary rock, which has skeletal fractions of marine creatures, such as molluscs and corals. It is impervious and hard with low water absorption capacity. The major constituents of limestone include mineral calcite and aragonite that are varied crystal forms of CaCO3, i.e., calcium carbonate.

Commonly white in colour, limestone exhibits various other shades due to impurities like clay, iron oxide, sand and organic matter. Brown, red or yellow colour is basically the result of iron oxide, while grey, black or blue colour of the limestone can be attributed to carbon impurities. The variations and intensity of the colour depend on the types and proportion of impurities in the limestone. The texture of limestone may vary from coarse to fine.

Depending on the process of its formation, limestone can be granular, crystalline or massive. Limestone has an exceptionally large number of uses. Apart from being used as animal feed filler, flux stone, aggregate for the base of roads and roofing granules; it finds extensive application in the construction industry and architectural designing as dimension stone.

Common applications of limestone in the construction sector include interior and exterior cladding, landscaping, paving, coping, statuary and flooring. For every purpose, different types of limestone are used that depends up on its physical properties, such as density, porosity, hardness as well as looks and texture. Several world-famous structures, both archaic and modern, are known to incorporate limestone in their construction. Megalithic Temples of Malta, Great Sphinx of Giza, Beer Quarry Caves, Lincoln Memorial and Empire State Building are the most prominent ones.

Limestone is chiefly concentrated in the states of Rajasthan and Andhra Pradesh. Most of the limestone quarries as well as limestone factories or processing units are located in Ramganjmandi in the Kota District in Rajasthan, and Kadapa District in Andhra Pradesh. The Indian variants of limestone can be broadly classified as North Indian and South India. North Indian variants include Kota Blue and Kota Brown, whereas South Indian varieties are Lime Black, Lime Green, Lime Peacock, Lime Pink, Tandur Blue and Tandur Yellow.

A number of limestone manufacturers and suppliers in India deal in North as well as South Indian varieties of limestone and Regatta Universal Exports is one prominent name in this sector. With approximately 17 years of experience in limestone manufacturing and export, Regatta Exports processes and exports premium-quality limestone in different countries in Europe, Middle East, North America and Australia.