Draft:Original research/Mining geology

Exploration for, discovery of, and removal of valuable natural resources from the Earth is mining geology.

Geology is often used to determine how to acquire the resource from its natural and sometimes dangerous location.

Def. a[n] "business [activity]^[1] of removing [solid]^[2] valuables from the earth"^[3] is called mining.

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While directional drilling includes vertical drilling, the term usually refers to angles less than vertical. These occur when what is sought cannot be reached by vertical drilling.

The second image down on the right shows miners within a coal mine shaft drilling at angles above and below horizontal to loosen coal for removal.

The horizontal flushing drill with the machine in the image on the left is a directional drilling technique for horizontal boring. This allows pipelines to be laid underground without having to dig out a trench. The drillings can be several hundred meters long. For the majority of all holes, diameters up to a maximum of 700 mm are sufficient.

Due to the low recycling rates, some landfills now contain higher concentrations of metal than mines themselves.^[4]

Remote sensing techniques, specifically hyperspectral imaging, have been used to detect hydrocarbon microseepages using the spectral signature of geochemically altered soils and vegetation.^[5][6]

Marine Magnetotellurics (mMT) or marine Controlled Source Electro-Magnetics (mCSEM) can provide pseudo-direct detection of hydrocarbons by detecting resistivity changes over geological traps (signaled by seismic survey), then minimizing the number of wellcats.^[7]

Full Waveform Inversion is a supercomputer technique recently use in conjunction with seismic sensors to explore for petroleum deposits offshore.^[8]

Offshore the risk can be reduced by using electromagnetic methods ^[9]

"Underground Coal Gasification (UCG) involves igniting coal in the ground, then collecting and using the gases that result from its partial combustion. Although the idea dates back over a century, very few UCG plants have ever been built. Underground gasification could potentially allow the use of coal that is currently uneconomical to mine. Underground gasification eliminates the need for strip mining and transportation of coal, as well as potentially making carbon capture and sequestration more practical. However, UCG produces large amounts of CO₂, and the coal combustion wastes that are left behind can leach pollutants into nearby groundwater, and have caused major contamination in UCG pilot projects."^[10]

"The form of UCG used in most modern projects consists of drilling two wells into a coal seam. Air or oxygen is injected into one well and a controlled combustion reaction is started in the seam itself - a more-controlled version of a natural coal seam fire. Gases are collected through the second well and are separated in a facility at the surface. This process produces primarily hydrogen and CO₂, with lesser amounts of carbon monoxide, methane, and trace amounts of other gases."^[10]

"These gases are then burned to produce energy, as in a natural gas plant. Hydrogen is the primary energy-containing gas in the mix. The combination of carbon monoxide and hydrogen is called syngas and can be combusted directly to produce heat or can be liquefied and refined in processes similar to that described for coal-to-liquids. Although CO₂ is one of the major products of UCG, it is simply a waste product and does not contain any recoverable energy. Because the combustion occurs underground, it heats the surrounding rock. This portion of the heat is not accessible for industrial use, therefore UCG burns more coal (per unit energy produced) than would be required if it was first mined. However, conventional mining and transport of coal also requires significant energy and have associated releases of greenhouse gases."^[10]

"Compared to conventional coal-fired power, underground gasification can greatly reduce the impacts associated with coal mining, coal dust, and the emissions of sulfur dioxide and nitrous oxides (responsible for acid rain and smog). However, UCG has several major environmental costs: contamination of ground water, subsidence of the overlying terrain, and global warming impacts. There is also a potential concern with the spread of underground coal seam fires, although this has not been observed in any trials to date."^[10]

"In underground gasification, there is no need for above ground disposal of coal combustion wastes such as coal ash. However, these pollutants are left behind in the coal seam, where they can leach out into surrounding groundwater. Groundwater contamination has been a major problem in almost all pilot UCG projects, most most well-documented in the Hoe Creek project managed by Lawrence Livermore Laboratory. The combustion of coal traps a variety of toxic substances such as mercury, phenol, and benzene into the former coal seam. Additionally, the solubility of heavy metals in water can be increased if the coal seam is fully oxidized. Pollutants can leach out through the surrounding rock, or be taken up by water that enters the chamber. The Chinchilla pilot project attempted to address this problem by maintaining negative pressure inside the coal combustion chamber to limit the outflow of containments. However, the technology to prevent contamination is in its infancy, and groundwater pollution remains the single biggest concern with UCG. Groundwater contamination is particularly worrisome since the pollution source deep underground is inaccessible and permanent. Problems may crop up at any time during or after the project (including decades or centuries later) and cleanup will be difficult or impossible. Waste remaining underground presents a problem into the indefinite future, making eventual leakage likely."^[10]

Sulfur is often surface mined from volcano deposits, as in the image on the right.

Road cuts are also an opportunity to explore for minerals.

"Although the tectonic uplift of the 3000 m to 5000 m high range has generally been assumed to be mostly Miocene in age, field relationships suggest that the Domeyko Fault System and tectonic uplift were active as early as the Eocene, coinciding with porphyry copper emplacement between 41 Ma and 30 Ma. Apatite fission track (FT) thermochronology provides both age data and a time-temperature history for rocks since they cooled below a temperature of ca. 125 degrees C (equivalent to a depth of 4 km to 5 km under normal geothermal gradients) on their way to the surface during exhumation, or after a heating event."^[11]

"Apatite FT data from the Paleozoic crystalline basement of the Domeyko Cordillera indicate that at least 4 km to 5 km of rocks were eroded during exhumation of this tectonic block between ca. 50 Ma to 30 Ma (Middle Eocene to Early Oligocene), a time that immediately precedes and overlaps with the emplacement of giant porphyry copper deposits. The FT data constrain the age and duration of a period of crustal thickening and extensive erosion known as the Incaic compression, an event recognized in the Andes of Chile and Peru."^[11]

The Talvivaara mine in Sotkamo, Finland, in the image on the right, extracts nickel from the Earth.

The recent history period dates from around 1,000 b2k to present.

Shipowners regarded the slaves as cargo to be transported to the Americas as quickly and cheaply as possible,^[12] there to be sold to work on coffee, tobacco, cocoa, sugar and cotton plantations, gold and silver mines, rice fields, construction industry, cutting timber for ships, in skilled labour, and as domestic servants.

Imperial Antiquity appears to have lasted from 2100 b2k to 1700 b2k.

In Great Britain the natives had mined minerals for millennia,^[13] but after the Roman conquest, the scale of the operations increased dramatically, as the Romans needed Britannia's resources, especially gold, silver, tin, and lead.

At Dolaucothi they stoped out the veins and drove adits through bare rock to drain the stopes. The same adits were also used to ventilate the workings, especially important when fire-setting was used. At other parts of the site, they penetrated the water table and dewatered the mines using several kinds of machines, especially reverse overshot water-wheels. These were used extensively in the copper mines at Rio Tinto in Spain, where one sequence comprised 16 such wheels arranged in pairs, and lifting water about 24 metres (79 ft). They were worked as treadmills with miners standing on the top slats. Many examples of such devices have been found in old Roman mines and some examples are now preserved in the British Museum and the National Museum of Wales.^[14]

The largest Roman lead mines were located in or near the Rio Tinto in southern Hispania.^[15][16]

Lead was essential to the smooth running of the Roman Empire.^[17]

In Britannia the largest sources of lead were at Mendip, South West England and especially at Charterhouse. In A.D. 49, six years after the invasion and conquest of Britain, the Romans had the lead mines of Mendip and those of Derbyshire, Shropshire, Yorkshire and Wales running at full shift. By A.D.70, Britain had surpassed Hispania as the leading lead-producing province. The Spanish soon lodged a complaint with the Emperor Vespasian, who in turn put limits on the amount of lead being produced in Britain. However British lead production continued to increase and ingots (or pigs) of lead have been found datable to the late second - early third century.^[18]

The process of extraction, cupellation, was fairly simple. First, the ore was smelted until the lead, which contained the silver, separated from the rock. The lead was removed, and further heated up to 1100° C using hand bellows. At this point, the silver separated from the lead, and was put into moulds which, when cooled, would form ingots that were to be sent all over the Roman Empire for minting.^[17]

There were many iron mines in Roman Britain. The index to the Ordnance Survey Map of Roman Britain lists 33 iron mines: 67% of these are in the Weald and 15% in the Forest of Dean. Because iron ores were widespread and iron was relatively cheap, the location of iron mines was often determined by the availability of wood, which Britain had in abundance, to make charcoal smelting fuel. Great amounts of iron were needed for the Roman war machine, and Britain was the perfect place to fill that need.^[19]

Many underground mines were constructed by the Romans. Once the raw ore was removed from the mine, it would be crushed, then washed. The less dense rock would wash away, leaving behind the iron oxide, which would then be smelted using the bloomery method. The iron was heated up to 1500 °C using charcoal. The remaining slag was removed and generally dumped.^[19]

The iron age history period began between 3,200 and 2,100 b2k.

"Whilst a relatively small proportion of Attica’s slaves worked on grand building projects, an enormous number – perhaps even 35,000 by 340 B.C.E. – worked in the mining region of southern Attica."^[20]

At other mines, such as on the island of Thassos, marble was quarried by the Parians after they arrived in the 7th century BC.^[21] 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.^[22]

The Late Bronze Ages begin about 3550 b2k and end about 2900 b2k.

Laurium or Lavrio or Lavrion; before early 11th century BC: Θορικός Thorikos; from Middle Ages until 1908: Εργαστήρια Ergastiria)^[23]

Although they had over 20,000 slaves working them, their technology was essentially identical to their Bronze Age predecessors.^[24]

The Middle Bronze Ages begin about 4100 b2k and end about 3550 b2k.

The Early Bronze Ages begin about 5300 b2k and end about 4100 b2k.

The earliest evidence for mining in the village of Thoricus dates to the beginning of the Bronze Age, ca. 3200 BC.^[25]

The "Atlantic period [is] 4.6–6 ka [4,600-6,000 b2k]."^[26]

Maadi today stands on the site of a town that has turned out to be a significant predynastic, Ancient Egyptian archaeological site, founded ca. 3500 B.C.^[27]

Ancient Egyptians mined malachite at Maadi.^[28] 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.^[29] 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.^[29]

The "Hasselo stadial [is] at approximately 40-38,500 ¹⁴C years B.P. (Van Huissteden, 1990)."^[30]

The "Hasselo Stadial [is a glacial advance] (44–39 ka ago)".^[31]

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.^[32][33] Mines of a similar age in Hungary are believed to be sites where Neanderthals may have mined flint for weapons and tools.^[34]

High quality flint found in northern France, southern England and Poland was used to create flint tools.^[35]

1. Ultimately, the best and final prospecting is on the ground by foot with detectors.

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