Quarry

A quarry is a type of open-pit mine from which rock or minerals are extracted. Quarries are generally used for extracting building materials, such as dimension stone, construction aggregate, riprap, sand, and gravel. They are often colocated with concrete and asphalt plants due to the requirement for large amounts of aggregate in those materials.



Problems

Quarries in level areas with shallow groundwater or which are located close to surface water often have engineering problems with drainage. Generally the water is removed by pumping while the quarry is operational, but for high inflows more complex approaches may be required. For example, the Coquina quarry is excavated to more than 60 feet (18 m) below sea level. To reduce surface leakage, a moat lined with clay was constructed around the entire quarry. Ground water entering the pit is pumped up into the moat. As a quarry becomes deeper water inflows generally increase and it also becomes more expensive to lift the water higher during removal - this can become the limiting factor in quarry depth. Some water-filled quarries are worked from beneath the water, by dredging.

Many people and municipalities consider quarries to be eyesores and require various abatement methods to address problems with noise, dust, and appearance. One of the more effective and famous examples of successful quarry restoration is Butchart Gardens in Victoria.

Many quarries naturally fill with water after abandonment and become lakes. Others are made into landfills.

Types of rock



Types of rock extracted from quarries include:

* Cinder
* Chalk
* China Clay
* Clay
* Coal
* Coquina
* Construction aggregate (sand and gravel)
* Globigerina Limestone (Malta)
* Granite
* Gritstone
* Gypsum
* Limestone
* Marble
* Ores
* Phosphate rock
* Sandstone
* Slate

From http://en.wikipedia.org/