A quarry is a place where rocks, sand, or minerals are extracted from the surface of Earth. A quarry is a type of mine called an open-pit mine, because it is open to Earth's surface. Another type of mine, a subsurface mine, consists of underground tunnels or shafts.

The most common purpose of quarries is to extract stone for building materials. Quarries have been used for thousands of years. The people of Kemet, ancient Egypt, built the Great Pyramids with massive limestone and granite blocks cut by hand from nearby quarries. Each of these blocks weighs many tons. In ancient Rome, enslaved people and incarcerated people were often forced to do the extremely difficult work of cutting stones in marble, granite, and limestone quarries.

Quarrying History

Methods of extracting stone and other materials from quarries have changed since the first quarries were mined in the Aswan area of Egypt. The earliest quarries were mined with hammers, picks, and chisels made of stone or metals such as bronze and iron.

Even communities that did not have stone buildings created quarries. The Lakota culture of the Midwest region of the U.S. and Canada did not quarry stone to build monuments or houses. At a site in Pipestone National Monument, in the U.S. state of Minnesota, they quarried for stones to make calumets, or ceremonial smoking pipes. Calumets, made of a type of metamorphic rock called catlinite or pipestone, were important for creating lasting treaties, or agreements between groups of people.

Quarrying material for use in building materials was much more work. Stones had to be carried or dragged out of quarries manually. Stones could also be hauled with pulley systems involving ropes and moveable wooden tracks or sleds. This process often involved thousands of slaves and other workers.

On Easter Island, for example, almost the entire community had to be involved in the quarrying, carving, and transportation of statues. The rock for these statues, called moai, was hauled all over the island from one quarry. The heaviest moai weighs 86 tons. Scientists are still studying how these ancient Polynesian people transported their quarried rock.

Today, people use mechanical tools to mine quarries, including drilling equipment, blasting equipment, and hauling equipment. Industrial drills with diamond tips are used to cut into hard rock. Some miners use explosives to blast away unwanted material to access the desired rock. Finally, materials are hauled away by enormous mining trucks. Some mining trucks can carry more than 350 tons of material.

Dimension Stones and Aggregate
Different types of stones are mined for different purposes. The two most common types of quarry material are dimension stones and aggregate.

Large, precisely cut stones excavated from a quarry are called dimension stones. Dimension stones are used for constructing buildings and monuments, or for decorating the outside of buildings. They are also used for kitchen counters and roofing shingles. Headstones, polished dimension stones usually made of granite, are used to mark graves in many countries.

Sand, gravel, or crushed rock excavated from a quarry is called aggregate. Aggregate is used in construction to create stable foundations for things like roads and railroad tracks.

Aggregate is also used to make concrete and asphalt. For this reason, asphalt and concrete plants are often built next to quarries. Asphalt is an oily substance that is mixed with aggregate for road construction. Concrete, invented by the ancient Romans, is a mixture of sticky stone cement and aggregate. The Romans depended on concrete and aggregate to build their vast system of roads and aqueducts, many of which are still standing today.

Quarries and the Environment
Quarries change their environment. They displace huge amounts of soil and plants, and force animals out of the area. Abandoned quarries rarely leave enough soil to allow life to return to the area.

Some abandoned quarries can fill with water, creating artificial lakes. Many of these lakes are clear and deep, creating a safe swimming environment for people and some aquatic animals, such as frogs and birds. Sometimes, however, lakes created by abandoned quarries have mining equipment left on the bottom, making them unsafe for swimming. Toxic materials exposed by mining activities can also leak into water at abandoned quarries.

Quarries are prone to flooding because they are sometimes dug below the water table. Toxic materials could seep into groundwater if an abandoned quarry's water reaches an area's water table. This is the concern surrounding the Berkeley Pit, a former copper quarry near Butte, Montana. The Berkeley Pit is one of the largest toxic waste sites in the U.S., and its water is within 61 meters (200 feet) of the area's water table.

To avoid contamination, miners must sometimes pump water out of quarries. Quarries are sealed from the surrounding water table. Abandoned quarries can also be turned into landfills.