Formation of rocks

The three main ways rocks are formed:

• Sedimentary rocks are formed through the gradual accumulation of sediment: for example, sand on a beach or mud on a river bed. As the sediment is buried it is compacted as more and more material is deposited on top. Eventually the sediment will become so dense that it is essentially rock. This process is known as lithification.
• Igneous rocks are rocks which have crystallized from a melt or magma. The melt is made up of various components of pre-existing rocks which have been subjected to melting either at subduction zones or within the Earth's mantle. The melt is hot and so passes upward through cooler country rock. As it moves it cools and various rock types will form through a process known as fractional crystallization. Igneous rocks can be seen at mid ocean ridges, areas of island arc volcanism or in intra-plate hotspots.
• Metamorphic rocks are rocks which once existed as igneous or sedimentary rocks but have been subjected to varying degrees of pressure and heat within the Earth's crust. The processes involved will change the composition and fabric of the rock and their original nature is often hard to distinguish. Metamorphic rocks are typically found in areas of mountain building.

Rock synthesis

The synthetic investigation of rocks proceeds by experimental work that attempts to reproduce different rock types and to elucidate their origins and structures. In many cases no experiment is necessary. Every stage in the origin of clays, sands and gravels can be seen in process around us, but where these have been converted into coherent shales, sandstone and conglomerates, and still more where they have experienced some degree of metamorphism, there are many obscure points about their history upon which experiment may yet throw light. Attempts have been made to reproduce igneous rocks, by fusion of mixtures of crushed minerals or of chemicals in specially contrived furnaces. The earliest researches of this sort are those of Faujas St Fond and of de Saussure, but Sir James Hall really laid the foundations of this branch of petrology. He showed (1798) that the whinstones (diabases) of Edinburgh were fusible and if rapidly cooled yielded black vitreous masses closely resembling natural pitchstones and obsidians, if cooled more slowly they consolidated as crystalline rocks not unlike the whinstones themselves and containing olivine, augite and feldspar (the essential minerals of these rocks).
Many years later Daubrée, Delesse and others carried on similar experiments, but the first notable advance was made in 1878, when Fouqué and Lévy began their researches. They succeeded in producing such rocks as porphyrite, leucite-tephrite, basalt and dolerite, and obtained also various structural modifications well known in igneous rocks, e.g. the porphyritic and the ophitic. Incidentally they showed that while many basic rocks (basalts, etc.) could be perfectly imitated in the laboratory, the acid rocks could not, and advanced the explanation that for the crystallization of the latter the gases never absent in natural rock magmas were indispensable mineralizing agents. It has subsequently been proved that steam, or such volatile substances as certain borates, molybdates, chlorides, fluorides, assist in the formation of orthoclase, quartz and mica (the minerals of granite). Sir James Hall also made the first contribution to the experimental study of metamorphic rocks by converting chalk into marble by heating it in a closed gun-barrel, which prevented the escape of the carbonic acid at high temperatures. In 1901 Adams and Nicholson carried this a stage further by subjecting marble to great pressures in hydraulic presses and have shown how the foliated structures, frequent in natural marbles, may be produced artificially.^[1]

Core–mantle boundary

he core–mantle boundary (CMB in the parlance of solid earth geophysicists) lies between the Earth's silicate mantle and its liquid iron-nickel outer core. This boundary is located at approximately 2900 km (1798 mi) depth beneath the Earth's surface. The boundary is observed via the discontinuity in seismic wave velocities at that depth. This discontinuity is due to the differences between the acoustic impedances of the solid mantle and the molten outer core. P-wave velocities are much slower in the outer core than in the deep mantle while S-waves do not exist at all in the liquid portion of the core. Recent evidence suggests a distinct boundary layer directly atop the CMB possibly made of a novel phase of the basic perovskite mineralogy of the deep mantle named post-perovskite. Seismic tomography studies have shown significant irregularities within the boundary zone and are suggestive of a possible organized structure as well as the presence of deep mantle plumes.
The ~200 km thick layer of the lower mantle directly above the boundary is referred to as the D′′ ("D double-prime" or "D prime prime") and is sometimes included in discussions regarding the core–mantle boundary zone.^[1] The D′′ name originates from the mathematician Keith Bullen's designations for the Earth's layers. His system was to label each layer alphabetically, A through G, with the crust as 'A' and the inner core as 'G'. In his 1942 publication of his model, the entire lower mantle was the D layer. In 1950, Bullen found his "D" layer to actually be two different layers. The upper part of the D layer, about 1800 km thick, was renamed D′ (D prime) and the lower part (the bottom 200 km) was named D′′.
The bottom of D′′ has been observed in some regions to be marked by a seismic velocity discontinuity (sometimes known as the 'Gutenberg discontinuity', after German geophysicist Beno Gutenberg) which besides features ultra-low velocity zones (ULVZs. ).^[2]

D'' Layer Demystified

MONTREAL--Deep within Earth, where hellish temperatures and pressures create crystals and structures like none ever seen on the surface, a strange undulated layer separates the mantle and the core. The composition of this region, called the d" layer (pronounced "dee double prime"), has puzzled earth scientists ever since its discovery. Now, a team of researchers believes they know what the d" layer is.
Three thousand kilometers deep in Earth, the solid rock of the mantle meets the liquid outer core. At this juncture, seismic waves from earthquakes traveling through Earth suddenly change speed, and sometimes direction. These sudden shifts trace the border of the d" layer, which rises and falls in ridges and valleys. Researchers suspected that the layer marks a change in the crystal structure of the rock, which might happen at different depths depending on the temperature. This would explain the rises and dips of the boundary. But what could account for the sudden speed shifts of the seismic waves?
The explanation may lie in an entirely new kind of crystal structure, according to presentations by Jun Tsuchiya and Taku Tsuchiya here 23 March at a meeting of the American Physical Society. The researchers, from the University of Minnesota, Twin Cities, used a diamond anvil to squeeze and heat a grain of perovskite, the dominant mineral deep within Earth. They then took an x-ray image to see what happened to the molecular structure of the mineral in conditions like those in the d" layer. Only one crystal structure fit the x-ray data, and it was like nothing anyone had seen before.
The team dubbed the new structure "post-perovskite." It has a distinctive sandwich-like structure, and the team's calculations indicate that seismic waves would travel through it at different speeds depending on their initial direction--just like they do at the d" layer. And post-perovskite would form at different depths in Earth depending on the temperature, in agreement with the earlier predictions.
"This may explain the d" layer--it gives us a direction to look in," says Oliver Tschauner of the University of Nevada, Las Vegas. However, Surendra Saxena of Florida International University in Miami isn't convinced. He believes that perovskite falls apart near the d" layer, and that computer models of the type used by the Minnesota group can't properly predict that: "This theory isn't perfect yet."

The End of D-Double-Prime?

There must be no branch of science with more names for invisible things than geology. The whole long history of Earth, for instance, is a gigantic hierarchy of eons, eras, periods, epochs, ages, and stages, each one known by a specific name. There are the P waves and S waves of seismology, and their various reflections within the Earth. There are the thousands of formally named rock units of stratigraphy—the Smith Formations and Jones Groups of the world, very few of them obvious to the eye. And there are the Richter magnitude and the Mercalli local intensity of earthquakes.
The layer of the Earth's deep interior known as "D-double-prime" may have the oddest name of them all.

How the D Layer Got Its Double-Prime

I first learned about the name 20 years ago, when I started following studies of the mantle. Where's D-single-prime, I wondered. Where's C or B, for that matter? No one ever said—it was ancient history. Every other part of the Earth has a word for its name, from the crust through the mantle to the inner core. But thanks to NASA's Benjamin Chao and the article he wrote in the 1 February 2000 Eos, I know that Keith Bullen gave it that name and I learned why.
Bullen was a New Zealander who lived from 1906 to 1976, publishing nearly 300 papers during his career. One of his great contributions was to build mathematical models of the Earth's interior, beginning in the 1930s. At that time we knew that Earth has a dense iron core surrounded by a thick rocky mantle, but he set out to add detail to the picture. Using the mechanical calculators of the time, Bullen laboriously worked out the seismic properties needed to account for the way the Earth bends earthquake waves.
To do his math, Bullen divided the planet into a series of shells or layers, labeled A through G. The crust was layer A and the inner core was G. In the first model he published, in 1942, the whole lower mantle, 2000 kilometers in thickness, was the D layer. By 1950 he had figured that the lower mantle was actually two very different layers, the lower one being a zone just a couple hundred kilometers thick. So in good mathematical fashion he divided D into D' and D"—D-prime and D-double-prime.

The Troubles of D"

Since that time the community of scientists has used the names we already had instead of Bullen's zones. The crust, upper mantle, transition zone, lower mantle, and inner and outer core fell neatly into his scheme. But that thin D" layer never got its own name, and in recent years it has gained quite a lot of attention. Chao's article recounts all this, and also mentions the trouble the name caused typesetters and indexers.
Not to mention the readers, unless you were already a seismologist. Seismologists had no problem in 1936 when Nature magazine published the famous paper by Inge Lehmann with the shortest title of all: "P'." They knew just from the author and title that Lehmann was reporting on an unusual P-wave she had detected. (It was the first evidence of the Earth's inner core.) But relying on the impenetrable name D" was practically a guarantee that no one outside the field would ever take an interest. The thing really needs an actual name.

Hell or Bullen?

One workaround long used by the deep-Earth community is to call this zone "the core-mantle boundary" or the CMB. But a boundary is a surface with no thickness, so this otherwise useful name has its basis in a fatal flaw. D" is a transitional zone between the mantle and core. But we already have a "transition zone" between the upper and lower mantle, so that possibility is out too.
A few years ago I suggested in a whimsical way that we should call this layer Hell instead of D". But Chao has a better idea. Call it the Bullen Layer, he says. "In so doing, rather than taking anything away from the originator, we pay tribute to the great seismologist, along with other well-known namesakes in seismology: Rayleigh and Love waves, Slichter and Stoneley modes, Gutenberg-Richter scale, Jeffreys-Bullen table, Benioff-Wadati zone, Mohorovicic discontinuity, and Lehmann discontinuity." So go read Bullen's biography and see if you agree that he should join the pantheon.
PS: Bullen also put a layer inside the core between F, the liquid outer core, and H, the solid inner core. His G layer is known today as the Lehmann discontinuity after another great seismologist, Inge Lehmann. She was lucky enough to enjoy the honor, around the time she turned 100.

metamorphism

Metamorphism is the solid-state recrystallization of pre-existing rocks due to changes in physical and chemical conditions, primarily heat, pressure, and the introduction of chemically active fluids. Mineralogical, chemical and crystallographic changes can occur during this process. Changes at or just beneath Earth's surface due to weathering and/or diagenesis are not classified as metamorphism.^[1]
Three types of metamorphism exist: contact, dynamic and regional. Metamorphism produced with increasing pressure and temperature conditions is known as prograde metamorphism. Conversely, decreasing temperatures and pressure characterize retrograde metamorphism.

Contents 1 Limits of metamorphism 2 Kinds of metamorphism 2.1 Regional metamorphism 2.2 Contact (thermal) metamorphism 2.3 Hydrothermal metamorphism 2.4 Shock metamorphism 2.5 Dynamic metamorphism 3 Classification of metamorphic rocks 3.1 Metamorphic facies 3.2 Metamorphic grades 4 Metamorphic processes 4.1 Recrystallization 4.2 Phase change 4.3 Neocrystallization 4.4 Pressure solution 4.5 Plastic deformation 5 Prograde and retrograde metamorphism 6 See also 7 References 8 External links

Limits of metamorphism

The temperature lower limit of metamorphism is considered to be 100 - 200 °C,^[2] to exclude diagenetic changes, due to compaction, which result in sedimentary rocks. There is no agreement on a pressure lower limit. Some workers argue that changes in atmospheric pressures are not metamorphic, but some types of metamorphism can occur at extremely low pressures (see below).
The upper boundary of metamorphic conditions is related to the onset of melting processes in the rock. The maximum temperature for metamorphism is typically 700 - 900 °C, depending on the pressure and on the composition of the rock. Migmatites are rocks formed at this upper limit, which contain pods and veins of material that has started to melt but has not fully segregated from the refractory residue. Since the 1980s it has been recognized that, rarely, rocks are dry enough and of a refractory enough composition to record without melting "ultra-high" metamorphic temperatures of 900 - 1100 °C.

Kinds of metamorphism

Regional metamorphism

Regional or Barrovian metamorphism covers large areas of continental crust typically associated with mountain ranges, particularly subduction zones or the roots of previously eroded mountains. Conditions producing widespread regionally metamorphosed rocks occur during an orogenic event. The collision of two continental plates or island arcs with continental plates produce the extreme compressional forces required for the metamorphic changes typical of regional metamorphism. These orogenic mountains are later eroded, exposing the intensely deformed rocks typical of their cores. The conditions within the subducting slab as it plunges toward the mantle in a subduction zone also produce regional metamorphic effects. The techniques of structural geology are used to unravel the collisional history and determine the forces involved. Regional metamorphism can be described and classified into metamorphic facies or metamorphic zones of temperature/pressure conditions throughout the orogenic terrane.

Contact (thermal) metamorphism

A metamorphic aureole in the Henry Mountains, Utah. The greyish rock on top is the igneous intrusion, consisting of porphyritic granodiorite from the Henry Mountains laccolith, and the pinkish rock on the bottom is the sedimentary country rock, a siltstone. In between, the metamorphosed siltstone is visible as both the dark layer (~5cm thick) and the pale layer below it.

Contact metamorphism occurs typically around intrusive igneous rocks as a result of the temperature increase caused by the intrusion of magma into cooler country rock. The area surrounding the intrusion where the contact metamorphism effects are present is called the metamorphic aureole.^[3] Contact metamorphic rocks are usually known as hornfels. Rocks formed by contact metamorphism may not present signs of strong deformation and are often fine-grained.
Contact metamorphism is greater adjacent to the intrusion and dissipates with distance from the contact. The size of the aureole depends on the heat of the intrusion, its size, and the temperature difference with the wall rocks. Dikes generally have small aureoles with minimal metamorphism whereas large ultramafic intrusions can have significantly thick and well-developed contact metamorphism.
The metamorphic grade of an aureole is measured by the peak metamorphic mineral which forms in the aureole. This is usually related to the metamorphic temperatures of pelitic or alumonisilicate rocks and the minerals they form.The metamorphic grades of aureoles are andalusite hornfels, sillimanite hornfels, pyroxene hornfels.
Magmatic fluids coming from the intrusive rock may also take part in the metamorphic reactions. Extensive addition of magmatic fluids can significantly modify the chemistry of the affected rocks. In this case the metamorphism grades into metasomatism. If the intruded rock is rich in carbonate the result is a skarn. Fluorine-rich magmatic waters which leave a cooling granite may often form greisens within and adjacent to the contact of the granite. Metasomatic altered aureoles can localize the deposition of metallic ore minerals and thus are of economic interest.

Hydrothermal metamorphism

Hydrothermal metamorphism is the result of the interaction of a rock with a high-temperature fluid of variable composition. The difference in composition between existing rock and the invading fluid triggers a set of metamorphic and metasomatic reactions. The hydrothermal fluid may be magmatic (originate in an intruding magma), circulating groundwater, or ocean water. Convective circulation of hydrothermal fluids in the ocean floor basalts produces extensive hydrothermal metamorphism adjacent to spreading centers and other submarine volcanic areas. The fluids eventually escape through vents in the ocean floor known as black smokers.^[4] The patterns of this hydrothermal alteration is used as a guide in the search for deposits of valuable metal ores.

Shock metamorphism

Main article: Shock metamorphism

This kind of metamorphism occurs when either an extraterrestrial object (a meteorite for instance) collides with the Earth's surface or during an extremely violent volcanic eruption. Impact metamorphism is, therefore, characterized by ultrahigh pressure conditions and low temperature. The resulting minerals (such as SiO₂ polymorphs coesite and stishovite) and textures are characteristic of these conditions.

Dynamic metamorphism

Dynamic metamorphism is associated with zones of high to moderate strain such as fault zones. Cataclasis, crushing and grinding of rocks into angular fragments, occurs in dynamic metamorphic zones, giving cataclastic texture.
The textures of dynamic metamorphic zones are dependent on the depth at which they were formed, as the temperature and confining pressure determine the deformation mechanisms which predominate. Within depths less than 5 km, dynamic metamorphism is not often produced because the confining pressure is too low to produce frictional heat. Instead, a zone of breccia or cataclasite is formed, with the rock milled and broken into random fragments. This generally forms a mélange. At depth, the angular breccias transit into a ductile shear texture and into mylonite zones.
Within the depth range of 5–10 km pseudotachylite is formed, as the confining pressure is enough to prevent brecciation and milling and thus energy is focused into discrete fault planes. Frictional heating in this case may melt the rock to form pseudotachylite glass.
Within the depth range of 10–20 km, deformation is governed by ductile deformation conditions and hence frictional heating is dispersed throughout shear zones, resulting in a weaker thermal imprint and distributed deformation. Here, deformation forms mylonite, with dynamothermal metamorphism observed rarely as the growth of porphyroblasts in mylonite zones.
Overthrusting may juxtapose hot lower crustal rocks against cooler mid and upper crust blocks, resulting in conductive heat transfer and localised contact metamorphism of the cooler blocks adjacent to the hotter blocks, and often retrograde metamorphism in the hotter blocks. The metamorphic assemblages in this case are diagnostic of the depth and temperature and the throw of the fault and can also be dated to give an age of the thrusting.

Classification of metamorphic rocks

Metamorphic rocks are classified by their mineral composition, the source rock, also known as a protolith, and the context (pressure, temperature, hydrological features, etc.) of its formation.

Metamorphic facies

Metamorphic facies are recognizable terranes or zones with an assemblage of key minerals that were in equilibrium under specific range of temperature and pressure during a metamorphic event. The facies are named after the metamorphic rock formed under those facies conditions from basalt. Facies relationships were first described by Pentti Eskola in 1921.

Metamorphic Facies with regard to temperature and pressure

Facies:

• Low T - Low P : Zeolite
• Mod - High T - Low P : Prehnite-Pumpellyite
• Low T - High P : Blueschist
• Mod to High T - Mod P : Greenschist - Amphibolite - Granulite
• Mod - High T - High P : Eclogite

See diagram for more detail.

Metamorphic grades

In the Barrovian sequence (described by George Barrow in zones of progressive metamorphism in Scotland), metamorphic grades are also classified by mineral assemblage based on the appearance of key minerals in rocks of pelitic (shaly, aluminous) origin:
Low grade ------------------- Intermediate --------------------- High grade

Greenschist ------------- Amphibolite ----------------------- Granulite

Slate --- Phyllite ---------- Schist ---------------------- Gneiss --- Migmatite

Chlorite zone

Biotite zone

Garnet zone

Staurolite zone

Kyanite zone

Sillimanite zone

Metamorphic processes

Recrystallization

During recrystallization, the grains making up the protolith change shape and size. The identity of the mineral does not change during this process, only the texture. Recrystallization occurs due to heating of the protolith. The temperature at which this occurs can vary depending on the minerals present. Recrystallization generally begins when temperatures reach above half the melting point of the mineral on the Kelvin scale.^[5]

Phase change

Phase change metamorphism is the creating of new minerals with the same chemical formula as the protolith. This involves a rearrangement of the atoms in the crystals.

Neocrystallization

Neocrystallization involves the creation of new mineral crystals different from the protolith. Chemical reactions digest the minerals of the protolith which yields new minerals. This is a very slow process as it can also involve the diffusion of atoms through solid crystals.

Pressure solution

Main article: Pressure solution

Pressure solution is a metamorphic process that requires a rock to be under strong pressure from one direction and in the presence of hot water. During this process mineral of the protolith partially dissolve, diffuse through the water and precipitate elsewhere.

Plastic deformation

In plastic deformation pressure is applied to the protolith, which causes it to shear or bend, but not break. In order for this to happen temperatures must be high enough that brittle fractures do not occur, but not so high that diffusion of crystals takes place.^[6]

Prograde and retrograde metamorphism

Metamorphism is further divided into prograde and retrograde metamorphism. Prograde metamorphism involves the change of mineral assemblages (paragenesis) with increasing temperature and (usually) pressure conditions. These are solid state dehydration reactions, and involve the loss of volatiles such as water or carbon dioxide. Prograde metamorphism results in rock characteristic of the maximum pressure and temperature experienced. Metamorphic rocks usually do not undergo further change when they are brought back to the surface.
Retrograde metamorphism involves the reconstitution of a rock via revolatisation under decreasing temperatures (and usually pressures), allowing the mineral assemblages formed in prograde metamorphism to revert to those more stable at less extreme conditions. This is a relatively uncommon process, because volatiles must be present.

Rock

In geology, a rock is a naturally occurring solid aggregate of one or more minerals or mineraloids. For example, the common rock, granite, is a combination of the quartz, feldspar and biotite minerals. The Earth's outer solid layer, the lithosphere, is made of rock.
Rocks have been used by mankind through out history. From the Stone Age rocks have been used for tools. The minerals and metals we find in rocks have been essential to human civilization.^[1]
Three major groups of rocks are defined: igneous, sedimentary, and metamorphic. The scientific study of rocks is called petrology, which is an essential component of geology.

Contents 1 Rock classification 1.1 Igneous rocks 1.2 Sedimentary rocks 1.3 Metamorphic rocks 2 Human use 2.1 Mining 3 See also 4 References

Rock classification

See also: Formation of rocks

Rock outcrop along a mountain creek near Orosí, Costa Rica.

Rocks are generally classified by mineral and chemical composition, by the texture of the constituent particles and by the processes that formed them. These indicators separate rocks into three types: igneous, sedimentary, and metamorphic. They are further classified according to particle size. The transformation of one rock type to another is described by the geological model called the rock cycle.

Sample of igneous gabbro

Igneous rocks are formed when molten magma cools and are divided into two main categories: plutonic rock and volcanic. Plutonic or intrusive rocks result when magma cools and crystallizes slowly within the Earth's crust (example granite), while volcanic or extrusive rocks result from magma reaching the surface either as lava or fragmental ejecta (examples pumice and basalt).^[2]

Sedimentary sandstone with iron oxide bands

Sedimentary rocks are formed by deposition of either clastic sediments, organic matter, or chemical precipitates (evaporites), followed by compaction of the particulate matter and cementation during diagenesis. Sedimentary rocks form at or near the Earth's surface. Mud rocks comprise 65% (mudstone, shale and siltstone); sandstones 20 to 25% and carbonate rocks 10 to 15% (limestone and dolostone).^[2]

Metamorphic banded gneiss

Metamorphic rocks are formed by subjecting any rock type (including previously formed metamorphic rock) to different temperature and pressure conditions than those in which the original rock was formed. These temperatures and pressures are always higher than those at the Earth's surface and must be sufficiently high so as to change the original minerals into other mineral types or else into other forms of the same minerals (e.g. by recrystallization).^[2]
The three classes of rocks—the igneous, the sedimentary and the metamorphic—are subdivided into many groups. There are, however, no hard and fast boundaries between allied rocks. By increase or decrease in the proportions of their constituent minerals they pass by every gradation into one another, the distinctive structures also of one kind of rock may often be traced gradually merging into those of another. Hence the definitions adopted in establishing rock nomenclature merely correspond to selected points (more or less arbitrary) in a continuously graduated series.^[3]

Igneous rocks

Main article: Igneous rock

Igneous rock (derived from the Latin word igneus meaning of fire, from ignis meaning fire) forms through the cooling and solidification of magma or lava. Igneous rock may form with or without crystallization, either below the surface as intrusive (plutonic) rocks or on the surface as extrusive (volcanic) rocks. This magma can be derived from partial melts of pre-existing rocks in either a planet's mantle or crust. Typically, the melting is caused by one or more of three processes: an increase in temperature, a decrease in pressure, or a change in composition. Over 700 types of igneous rocks have been described, most of them having formed beneath the surface of Earth's crust. These have diverse properties, depending on their composition and how they were formed.

Sedimentary rocks

Main article: Sedimentary rock

Sedimentary rocks are types of rock that are formed by the deposition of material at the Earth's surface and within bodies of water. Sedimentation is the collective name for processes that cause mineral and/or organic particles (detritus) to settle and accumulate or for minerals to precipitate from a solution. Particles that form a sedimentary rock by accumulating are called sediment. Before being deposited, sediment was formed by weathering and erosion in a source area, and then transported to the place of deposition by water, wind, ice, mass movement or glaciers which are called agents of denudation.

Metamorphic rocks

Main article: Metamorphic rock

Metamorphic rocks arise from the transformation of existing rock types, in a process called metamorphism, which means "change in form". The original rock (protolith) is subjected to heat and pressure, (temperatures greater than 150 to 200 °C and pressures of 1500 bars^[4]) causing profound physical and/or chemical change. The protolith may be sedimentary rock, igneous rock or another older metamorphic rock.

Human use

Ceremonial cairn of rocks, an ovoo, from Mongolia

Uranium mine near Moab, Utah

The use of rocks has had a huge impact on the cultural and technological development of the human race. Rocks have been used by humans and other hominids for more than 2 million years.^{[5][not in citation given]} Lithic technology marks some of the oldest and continuously used technologies. The mining of rocks for their metal ore content has been one of the most important factors of human advancement, which has progressed at different rates in different places in part because of the kind of metals available from the rocks of a region.^{[6][not in citation given]}

Mining

Main article: Mining

Mining is the extraction of valuable minerals or other geological materials from the earth, from an ore body, vein or (coal) seam. This term also includes the removal of soil. Materials recovered by mining include base metals, precious metals, iron, uranium, coal, diamonds, limestone, oil shale, rock salt and potash. Mining is required to obtain any material that cannot be grown through agricultural processes, or created artificially in a laboratory or factory. Mining in a wider sense comprises extraction of any non-renewable resource (e.g., petroleum, natural gas, or even water).
Mining of stone and metal has been done since pre-historic times. Modern mining processes involve prospecting for ore bodies, analysis of the profit potential of a proposed mine, extraction of the desired materials and finally reclamation of the land to prepare it for other uses once the mine is closed.
The nature of mining processes creates a potential negative impact on the environment both during the mining operations and for years after the mine is closed. This impact has led to most of the world's nations adopting regulations to moderate the negative effects of mining operations. Safety has long been a concern as well, though modern practices have improved safety in mines significantly.

punjabi lyrics

Lyrics - Asaan Ishq namaaz jadon neeti ay,

Asaan Ishq namaaz jadon neeti ay,
Tadon bhul gaye mandar maseeteeay,
Jhangar kanon jhungar changa,
Jaihn wich lakan kuttay,
taykan utay,
Mullah kanoon kukar changa,
Jeera yaar jagaway sutay,
Taykan utay,
Babhan kanoon kalal changa,
Jeera khari peya vi chukay,
taykan utay,
Ve miyan bulleya chal yaar mana lay,
nae tay bazi lay gaye kuttay,
uaykan utay,
Mullah choor day ilm kitaban da,
Awaen chukeyae baar azaban da,
wojo karkay shook sharaban da,
taday andar bahar paleetee ay.
Asaan ishq namaaz jadon neetee ay,
tadoon bhul gaye mandar maseeteay.
kawan day bachay hans na honday,
toray mooti choog chugaeay hoo,
koray phoo na mithay honday,
toray so man khand da paeay hoo,
taykon Ka’abay day wich paya noor dissay,
Saday but-khanay wich Huzoor wasay,
Sab nayray taykon door wasay,
Taydi neeyat wich badneetee ay,
Asaan Ishq Namaaz jadon neetee ay,
Tadon bhul gaye mandar maseeteeay.
Tussan uchay tusandi zaat uchi,
Tussan Uch shahar day rahan walay,
Asaan kasoori, sadi zaat kasoori,
Asaan shaher Kasoor day rahan walay.
Bulleh nach ke yaar manaya ay,
Sara dil da kufar gawaya ay.
Apnay dil ka maqsad paya ay,
Jadon nazar inayat keetee ay,
Asaan ishq namaaz jadon neetee ay,
Tadon bhul gaye mandar maseeteeay.