Marble

Composed of calcite or dolomite, or a combination of both, Marble is a metamorphic rock, which finds wide usage in buildings, monuments, and sculptures. Commercially however, all calcareous rocks produced by nature and capable being polished are called marbles.

The heat and pressure in the earth's crust leads to re-crystallization of limestone over a period of time, which forces the limestone to change its texture and makeup. Fossilized materials in the limestone, along with its original carbonate minerals, re-crystallize and form large, coarse grains of calcite. Impurities present in the limestone during re-crystallization affect the mineral composition of the marble that forms. The minerals that result from impurities give marble wide variety of colors. The purest calcite marble is white in color. So in broader sense True Marble is metamorphosed limestone.

Aesthetically more beautiful and available in wider range of colors, Marbles are valued more than limestone, though they share similar characteristics and applications to limestones. Marbles are suitable for both interior and exterior applications.

Extremely pure calcite marble is used for most statues. Large blocks of colored marble are, used for columns, floors, and other parts of buildings. Smaller pieces of such marble are crushed or finely ground and used as abrasives in soaps and other products. Crushed or ground marble is also used in paving roads and in manufacturing roofing materials and soil treatment products. Valued for its beauty and strength, this precious stone is resistant to fire and erosion.

Mining and Processing
Marble is mined by opencast method except in Chausera quarries of Makrana where underground mining to a depth of about 100 m is resorted to exploit excellent white marble. In order to obtain desired dimensions of marble blocks, the method adopted for mining marble differs substantially from that of other minerals. The operations to mine marble by open-pit mining involve stripping, primary separation and secondary separations with trimming. There are three important centres of mining marble in India. They are Makrana (Rajasthan), Antri-Beharipur (Haryana) and Zarivev (Gujarat). The blocks obtained are dressed into a regular shape by wedging and fracturing. Processing of marble involves three main activities. They are: sawing, polishing and edge-cutting.