Mining

Mining is the extraction of valuable geological materials and minerals from the surface of the Earth. Mining is required to obtain most materials that cannot be grown through agricultural processes, or feasibly created artificially in a laboratory or factory. Ores recovered by mining include metals, coal, oil shale, gemstones, limestone, chalk, dimension stone, rock salt, potash, gravel, and clay. The ore must be a rock or mineral that contains valuable constituent, can be extracted or mined and sold for profit. Mining in a wider sense includes extraction of any non-renewable resource such as petroleum, natural gas, or even water.

Modern mining processes involve prospecting for ore bodies, analysis of the profit potential of a proposed mine, extraction of the desired materials, and final reclamation or restoration of the land after the mine is closed. Mining materials are often obtained from ore bodies, lodes, veins, seams, reefs, or placer deposits. The exploitation of these deposits for raw materials is dependent on investment, labor, energy, refining, and transportation cost.

Mining operations can create a negative environmental impact, both during the mining activity and after the mine has closed. Hence, most of the world's nations have passed regulations to decrease the impact; however, the outsized role of mining in generating business for often rural, remote or economically depressed communities means that governments often fail to fully enforce such regulations. Work safety has long been a concern as well, and where enforced, modern practices have significantly improved safety in mines. Unregulated, poorly regulated or illegal mining, especially in developing economies, frequently contributes to local human rights violations and environmental conflicts. Mining can also perpetuate political instability through resource conflicts.

Since the beginning of civilization, people have used stone, clay and, later, metals found close to the Earth's surface. These were used to make early tools and weapons; for example, high quality flint found in northern France, southern England and Poland was used to create flint tools. Flint mines have been found in chalk areas where seams of the stone were followed underground by shafts and galleries. The mines at Grimes Graves and Krzemionki are especially famous, and like most other flint mines, are Neolithic in origin (c. 4000–3000 BC). Other hard rocks mined or collected for axes included the greenstone of the Langdale axe industry based in the English Lake District. The oldest-known mine on archaeological record is the Ngwenya Mine in Eswatini (Swaziland), which radiocarbon dating shows to be about 43,000 years old. At this site Paleolithic humans mined hematite to make the red pigment ochre. Mines of a similar age in Hungary are believed to be sites where Neanderthals may have mined flint for weapons and tools.

Ancient Egyptians mined malachite at Maadi. At first, Egyptians used the bright green malachite stones for ornamentations and pottery. Later, between 2613 and 2494 BC, large building projects required expeditions abroad to the area of Wadi Maghareh in order to secure minerals and other resources not available in Egypt itself. Quarries for turquoise and copper were also found at Wadi Hammamat, Tura, Aswan and various other Nubian sites, on the Sinai Peninsula, and at Timna. Quarries for gypsum were found at the Umm el-Sawwan site; gypsum was used to make funerary items for private tombs. Other minerals mined in Egypt from the Old Kingdom (2649-2134 BC) until the Roman Period (30 BC-AD 395) including granite, sandstone, limestone, basalt, travertine, gneiss, galena, and amethyst.

Mining in Egypt occurred in the earliest dynasties. The gold mines of Nubia were among the largest and most extensive of any in Ancient Egypt. These mines are described by the Greek author Diodorus Siculus, who mentions fire-setting as one method used to break down the hard rock holding the gold. One of the complexes is shown in one of the earliest known mining maps. The miners crushed the ore and ground it to a fine powder before washing the powder for the gold dust known as the dry and wet attachment processes.

Mining in Europe has a very long history. Examples include the silver mines of Laurium, which helped support the Greek city state of Athens. Although they had over 20,000 slaves working them, their technology was essentially identical to their Bronze Age predecessors. At other mines, such as on the island of Thassos, marble was quarried by the Parians after they arrived in the 7th century BC. The marble was shipped away and was later found by archaeologists to have been used in buildings including the tomb of Amphipolis. Philip II of Macedon, the father of Alexander the Great, captured the gold mines of Mount Pangeo in 357 BC to fund his military campaigns. He also captured gold mines in Thrace for minting coinage, eventually producing 26 tons per year.

However, it was the Romans who developed large-scale mining methods, especially the use of large volumes of water brought to the minehead by numerous aqueducts. The water was used for a variety of purposes, including removing overburden and rock debris, called hydraulic mining, as well as washing comminuted, or crushed, ores and driving simple machinery.