Quarrying << KWAWR ee ihng >> is a method of mining a deposit that lies at the surface of the earth. This method is commonly used to dig out large slabs or blocks of stone called dimension stone. The stone is removed from a large pit called a quarry. Quarries have nearly vertical walls that in some cases can be 1,000 feet (300 meters) high. Dimension stone cut from quarries includes flagstone, granite, limestone, marble, sandstone, and slate. It is used mainly as a building material and for flooring and decorative wall coverings.
The value of dimension stone depends on its color, strength, and freedom from cracks and flaws. To preserve these qualities, workers must remove the stone from a quarry with great care. Workers begin the quarrying of a deposit by removing a large section of stone called a key block. They separate individual blocks from the surrounding rock by channeling, cutting, or sawing. When the stone has been taken from the entire length and width of the quarry, workers remove another key block to establish a new working level. Quarrying is not a very common method of mining because only limited amounts of dimension stone are used each year.
The word quarrying is sometimes used to refer to the removal of such materials as crushed rock and gravel from an open pit. These materials are mined in enormous amounts each year.
See also Mining (Surface mining methods).
