open, or surface, excavation of rock used for various purposes, including construction, ornamentation, road building, and as an industrial raw material. Rock that has been quarried is commonly called stone. Quarrying methods depend chiefly on the desired size and shape of the stone and its physical characteristics. For industrial use (e.g., limestone for preparing cement), as the aggregate in concrete, or for road beds, the rock is shattered. Explosives are detonated in a series of holes drilled in the rock in a pattern designed to yield the greatest amount of fracturing. The rock fragments may be further reduced in crushing machines and sorted according to size by screening. For building stone, rocks that do not shatter are separated by blasting; for softer rocks or when explosives cannot be used (e.g., because they would disturb adjacent workings), a process known as broaching, or channeling, is used. In this process a line of holes is drilled perpendicular to the joints or cleavage planes of a formation; wedges are inserted into the holes and hammered until the stone splits off. This method was probably used in ancient times, notably by the Incas and the Egyptians. Much quarrying of ornamental stone today is done by using pneumatically operated channelers. After the vertical cuts have been made, gadding machines (working on the same principle) are used to make horizontal cuts. Wedges are then used to split off the long blocks, which are subdivided and removed. Wire saws are also used; these consist of several pulleys over which passes an endless steel wire. Holes are drilled in the rock, each hole being made large enough to accommodate a pulley and the shaft to which it is attached. The wire, extending from one pulley to another, presses down against the rock between them. As the cut is deepened by the constantly moving wire the pulleys are continuously lowered into the holes.
The art of taking stones of various sizes from natural rocks is known as quarrying. Open part of the natural rock from which useful material is obtained is known as quarry. Purpose of quarrying is to obtain stones for masonry, for ballast in concrete, road construction, on railway track or for any other purpose.
Quarry and its location :
In locating a quarry the points that should be kept in view are :
(1) The required building stone should be available in sufficient quantities at or near the surface of the ground.
(2) Sufficient labour at cheap rates should be locally available.
(3) Ample means of communications should be available.
(4) Power should be cheaply available.
(5) Sufficient quantities of clean water should be available all the year round.
(6) Drainage of rain water should present no problem.
(7) Site for the dumping of refuse should be easily available nearby.
(8) There should be no permanent structures nearby in the case of quarrying by Blasting.