Gold is a chemical element with symbol Au and atomic number 79, making it one of the higher atomic number elements that occur naturally. In its purest form, it is a bright reddish yellow, soft and ductile metal. Chemically, gold is a group 11 element, it is solid under standard conditions. Gold occurs in free elemental form, as nuggets or grains, in rocks, in veins, in alluvial deposits, it occurs in a solid solution series with the native element silver and naturally alloyed with copper and palladium. Less it occurs in minerals as gold compounds with tellurium. Gold is resistant to most acids, though it does dissolve in aqua regia, a mixture of nitric acid and hydrochloric acid, which forms a soluble tetrachloroaurate anion. Gold is insoluble in nitric acid, which dissolves silver and base metals, a property that has long been used to refine gold and to confirm the presence of gold in metallic objects, giving rise to the term acid test. Gold dissolves in alkaline solutions of cyanide, which are used in mining and electroplating.
Gold dissolves in mercury, forming amalgam alloys. A rare element, gold is a precious metal, used for coinage and other arts throughout recorded history. In the past, a gold standard was implemented as a monetary policy, but gold coins ceased to be minted as a circulating currency in the 1930s, the world gold standard was abandoned for a fiat currency system after 1971. A total of 186,700 tonnes of gold exists above ground, as of 2015; the world consumption of new gold produced is about 50% in jewelry, 40% in investments, 10% in industry. Gold's high malleability, resistance to corrosion and most other chemical reactions, conductivity of electricity have led to its continued use in corrosion resistant electrical connectors in all types of computerized devices. Gold is used in infrared shielding, colored-glass production, gold leafing, tooth restoration. Certain gold salts are still used as anti-inflammatories in medicine; as of 2017, the world's largest gold producer by far was China with 440 tonnes per year.
Gold is the most malleable of all metals. It can be drawn into a monoatomic wire, stretched about twice before it breaks; such nanowires distort via formation and migration of dislocations and crystal twins without noticeable hardening. A single gram of gold can be beaten into a sheet of 1 square meter, an avoirdupois ounce into 300 square feet. Gold leaf can be beaten thin enough to become semi-transparent; the transmitted light appears greenish blue, because gold reflects yellow and red. Such semi-transparent sheets strongly reflect infrared light, making them useful as infrared shields in visors of heat-resistant suits, in sun-visors for spacesuits. Gold is a good conductor of electricity. Gold has a density of 19.3 g/cm3 identical to that of tungsten at 19.25 g/cm3. By comparison, the density of lead is 11.34 g/cm3, that of the densest element, osmium, is 22.588±0.015 g/cm3. Whereas most metals are gray or silvery white, gold is reddish-yellow; this color is determined by the frequency of plasma oscillations among the metal's valence electrons, in the ultraviolet range for most metals but in the visible range for gold due to relativistic effects affecting the orbitals around gold atoms.
Similar effects impart a golden hue to metallic caesium. Common colored gold alloys include the distinctive eighteen-karat rose gold created by the addition of copper. Alloys containing palladium or nickel are important in commercial jewelry as these produce white gold alloys. Fourteen-karat gold-copper alloy is nearly identical in color to certain bronze alloys, both may be used to produce police and other badges. White gold alloys can be made with nickel. Fourteen- and eighteen-karat gold alloys with silver alone appear greenish-yellow and are referred to as green gold. Blue gold can be made by alloying with iron, purple gold can be made by alloying with aluminium. Less addition of manganese, aluminium and other elements can produce more unusual colors of gold for various applications. Colloidal gold, used by electron-microscopists, is red. Gold has only one stable isotope, 197Au, its only occurring isotope, so gold is both a mononuclidic and monoisotopic element. Thirty-six radioisotopes have been synthesized, ranging in atomic mass from 169 to 205.
The most stable of these is 195Au with a half-life of 186.1 days. The least stable is 171Au. Most of gold's radioisotopes with atomic masses below 197 decay by some combination of proton emission, α decay, β+ decay; the exceptions are 195Au, which decays by electron capture, 196Au, which decays most by electron capture with a minor β− decay path. All of gold's radioisotopes with atomic masses above 197 decay by β− decay. At least 32 nuclear isomers have been characterized, ranging in atomic mass from 170 to 200. Within that range, only 178Au, 180Au, 181Au, 182Au, 188Au do not have isomers. Gold's most stable isomer is 198m2Au with a half-life of 2.27 days. Gold's least stable isomer is 177m2Au with a half-life of only 7 ns. 184m1Au has three decay paths: β+ decay, isomeric
"Gold nugget" may refer to the catfish Baryancistrus xanthellus or the mango cultivar Gold Nugget. A gold nugget is a occurring piece of native gold. Watercourses concentrate nuggets and finer gold in placers. Nuggets are recovered by placer mining, but they are found in residual deposits where the gold-bearing veins or lodes are weathered. Nuggets are found in the tailings piles of previous mining operations those left by gold mining dredges. Nuggets are gold fragments weathered out of an original lode, they show signs of abrasive polishing by stream action, sometimes still contain inclusions of quartz or other lode matrix material. A 2007 study on Australian nuggets ruled out speculative theories of supergene formation via in-situ precipitation, cold welding of smaller particles, or bacterial concentration, since crystal structures of all of the nuggets examined proved they were formed at high temperature deep underground. Other precious metals such as platinum form nuggets in the same way. A study of native gold from Arizona, US, based on lead isotopes indicates that a significant part of the mass in alluvial gold nuggets in this area formed within the placer environment.
Nuggets are 20.5K to 22K purity. Gold nuggets in Australia are 23K or higher, while Alaskan nuggets are at the lower end of the spectrum. Purity can be assessed by the nugget color, the richer and deeper the orange-yellow the higher the gold content. Nuggets are referred to by their fineness, for example "865 fine" means the nugget is 865 parts per thousand in gold by mass; the common impurities are copper. Nuggets high in silver content constitute the alloy electrum. Two gold nuggets are claimed as the largest in the world: the Welcome Stranger and the Canaã nugget, the latter being the largest surviving natural nugget. Considered by most authorities to be the biggest gold nugget found, the Welcome Stranger was found at Moliagul, Australia in 1869 by John Deason and Richard Oates, it returned over 2,284 troy ounces net. The Welcome Stranger is sometimes confused with the named Welcome Nugget, found in June 1858 at Bakery Hill, Australia by the Red Hill Mining Company; the Welcome weighed 2,218 troy ounces.
It was melted down in London in November 1859. The Canaã nugget known as the Pepita Canaa, was found on September 13, 1983 by miners at the Serra Pelada Mine in the State of Para, Brazil. Weighing 1,955 troy ounces gross, containing 1,682.5 troy ounces of gold, it is among the largest gold nuggets found, is, the largest in existence. The main controversy regarding this nugget is that the excavation reports suggest that the existing nugget was part of a nugget weighing 5,291.09 troy ounces that broke during excavations. The Canaã nugget is displayed at the Banco Central Museum in Brazil along with the second and third largest nuggets remaining in existence, weighing 1,506.2 troy ounces and 1,393.3 troy ounces, which were found at the Serra Pelada region. The largest gold nugget found using a metal detector is the Hand of Faith, weighing 875 troy ounces, found in Kingower, Australia in 1980. Historic large specimens include the crystalline "Fricot Nugget", weighing 201 troy ounces – the largest one found during the California Gold Rush.
It is on display at the California State Mineral Museum. The largest gold nugget found in California weighed 1,593 troy ounces, it was found in August 1869 in Sierra Buttes by five partners – W. A. Farish, A. Wood, J. Winstead, F. N. L. Clevering and Harry Warner; the Victoria, Australia gold rush of the early 1850s produced a number of large nuggets. They include the Welcome Nugget which weighed 68.98 kilograms, considered to be the second largest gold nugget found. Another find, the Lady Hotham, which weighed 98.5 pounds, was found by a group of nine miners on September 8, 1854 in Canadian Gully, Ballarat at a depth of 135 feet. The Lady Hotham was named after the wife of the Governor, Sir Charles Hotham who happened to be visiting the area when the nugget was found. Eighteen months earlier, in January and early February 1853, three other large nuggets weighing 134 pounds, 93.125 pounds, 83.5 pounds were found in Canadian Gully at a depth of 55 to 60 feet. Another nugget, the Heron, was found in 1855 in Golden Gully in the Mount Alexander goldfield.
It weighed 1,008 troy ounces and was found by a group of inexperienced miners who had received a empty claim. The miners found the nugget on their second day of digging. On 16 January 2013, a large gold nugget was found near the city of Ballarat in Victoria, Australia by an amateur gold prospector; the Y-shaped nugget weighed more than 5 kilograms, measured around 22 cm high by 15 cm wide, has a market value below 300,000 Australian dollars, though opinions have been expressed that it could be sold for much more due to its rarity. The discovery has cast doubt on the common rumour that Victoria's goldfields were exhausted in the 19th century. Gold mining Gold prospecting Gold rush Beyers-Holtermann Specimen, the largest specimen of native gold found. Reef gold thus with quartz and therefore not a nugget, it contained ap
An ore is an occurrence of rock or sediment that contains sufficient minerals with economically important elements metals, that can be economically extracted from the deposit. The ores are extracted from the earth through mining; the ore grade, or concentration of an ore mineral or metal, as well as its form of occurrence, will directly affect the costs associated with mining the ore. The cost of extraction must thus be weighed against the metal value contained in the rock to determine what ore can be processed and what ore is of too low a grade to be worth mining. Metal ores are oxides, silicates, or native metals that are not concentrated in the Earth's crust, or noble metals such as gold; the ores must be processed to extract the elements of interest from the waste rock and from the ore minerals. Ore bodies are formed by a variety of geological processes; the process of ore formation is called ore genesis. An ore deposit is an accumulation of ore; this is distinct from a mineral resource. An ore deposit is one occurrence of a particular ore type.
Most ore deposits are named according to their location, or after a discoverer, or after some whimsy, a historical figure, a prominent person, something from mythology or the code name of the resource company which found it. Ore deposits are classified according to various criteria developed via the study of economic geology, or ore genesis; the classifications below are typical. Mesothermal lode gold deposits, typified by the Golden Mile, Kalgoorlie Archaean conglomerate hosted gold-uranium deposits, typified by Elliot Lake, Ontario and Witwatersrand, South Africa Carlin–type gold deposits, including. Volcanic hosted massive sulfide Cu-Pb-Zn including. Stratiform arkose-hosted and shale-hosted copper, typified by the Zambian copperbelt. Stratiform tungsten, typified by the Erzgebirge deposits, Czechoslovakia Exhalative spilite-chert hosted gold deposits Mississippi valley type zinc-lead deposits Hematite iron ore deposits of altered banded iron formation Sudbury Basin nickel and copper, Canada The basic extraction of ore deposits follows these steps: Prospecting or exploration to find and define the extent and value of ore where it is located Conduct resource estimation to mathematically estimate the size and grade of the deposit Conduct a pre-feasibility study to determine the theoretical economics of the ore deposit.
This identifies, early on, whether further investment in estimation and engineering studies is warranted and identifies key risks and areas for further work. Conduct a feasibility study to evaluate the financial viability and financial risks and robustness of the project and make a decision as whether to develop or walk away from a proposed mine project; this includes mine planning to evaluate the economically recoverable portion of the deposit, the metallurgy and ore recoverability and payability of the ore concentrates, engineering and infrastructure costs and equity requirements and a cradle to grave analysis of the possible mine, from the initial excavation all the way through to reclamation. Development to create access to an ore body and building of mine plant and equipment The operation of the mine in an active sense Reclamation to make land where a mine had been suitable for future use Ores are traded internationally and comprise a sizeable portion of international trade in raw materials both in value and volume.
This is because the worldwide distribution of ores is unequal and dislocated from locations of peak demand and from smelting infrastructure. Most base metals are traded internationally on the London Metal Exchange, with
Quartz is a mineral composed of silicon and oxygen atoms in a continuous framework of SiO4 silicon–oxygen tetrahedra, with each oxygen being shared between two tetrahedra, giving an overall chemical formula of SiO2. Quartz is the second most abundant mineral behind feldspar. Quartz exists in two forms, the normal α-quartz and the high-temperature β-quartz, both of which are chiral; the transformation from α-quartz to β-quartz takes place abruptly at 573 °C. Since the transformation is accompanied by a significant change in volume, it can induce fracturing of ceramics or rocks passing through this temperature threshold. There are many different varieties of quartz. Since antiquity, varieties of quartz have been the most used minerals in the making of jewelry and hardstone carvings in Eurasia; the word "quartz" is derived from the German word "Quarz", which had the same form in the first half of the 14th century in Middle High German in East Central German and which came from the Polish dialect term kwardy, which corresponds to the Czech term tvrdý.
The Ancient Greeks referred to quartz as κρύσταλλος derived from the Ancient Greek κρύος meaning "icy cold", because some philosophers believed the mineral to be a form of supercooled ice. Today, the term rock crystal is sometimes used as an alternative name for the purest form of quartz. Quartz belongs to the trigonal crystal system; the ideal crystal shape is a six-sided prism terminating with six-sided pyramids at each end. In nature quartz crystals are twinned, distorted, or so intergrown with adjacent crystals of quartz or other minerals as to only show part of this shape, or to lack obvious crystal faces altogether and appear massive. Well-formed crystals form in a'bed' that has unconstrained growth into a void. However, doubly terminated crystals do occur where they develop without attachment, for instance within gypsum. A quartz geode is such a situation where the void is spherical in shape, lined with a bed of crystals pointing inward. Α-quartz crystallizes in the trigonal crystal system, space group P3121 or P3221 depending on the chirality.
Β-quartz belongs to space group P6222 and P6422, respectively. These space groups are chiral. Both α-quartz and β-quartz are examples of chiral crystal structures composed of achiral building blocks; the transformation between α- and β-quartz only involves a comparatively minor rotation of the tetrahedra with respect to one another, without change in the way they are linked. Although many of the varietal names arose from the color of the mineral, current scientific naming schemes refer to the microstructure of the mineral. Color is a secondary identifier for the cryptocrystalline minerals, although it is a primary identifier for the macrocrystalline varieties. Pure quartz, traditionally called rock crystal or clear quartz, is colorless and transparent or translucent, has been used for hardstone carvings, such as the Lothair Crystal. Common colored varieties include citrine, rose quartz, smoky quartz, milky quartz, others; these color differentiation's arise from chromophores which have been incorporated into the crystal structure of the mineral.
Polymorphs of quartz include: α-quartz, β-quartz, moganite, cristobalite and stishovite. The most important distinction between types of quartz is that of macrocrystalline and the microcrystalline or cryptocrystalline varieties; the cryptocrystalline varieties are either translucent or opaque, while the transparent varieties tend to be macrocrystalline. Chalcedony is a cryptocrystalline form of silica consisting of fine intergrowths of both quartz, its monoclinic polymorph moganite. Other opaque gemstone varieties of quartz, or mixed rocks including quartz including contrasting bands or patterns of color, are agate, carnelian or sard, onyx and jasper. Amethyst is a form of quartz that ranges from a dull purple color; the world's largest deposits of amethysts can be found in Brazil, Uruguay, France and Morocco. Sometimes amethyst and citrine are found growing in the same crystal, it is referred to as ametrine. An amethyst is formed. Blue quartz contains inclusions of fibrous crocidolite. Inclusions of the mineral dumortierite within quartz pieces result in silky-appearing splotches with a blue hue, shades giving off purple and/or grey colors additionally being found.
"Dumortierite quartz" will sometimes feature contrasting light and dark color zones across the material. Interest in the certain quality forms of blue quartz as a collectible gemstone arises in India and in the United States. Citrine is a variety of quartz whose color ranges from a pale yellow to brown due to ferric impurities. Natural citrines are rare. However, a heat-treated amethyst will have small lines in the crystal, as opposed to a natural citrine's cloudy or smokey appearance, it is nearly impossible to differentiate between cut citrine and yellow topaz visually, but they differ in hardness. Brazil is the leading producer of citrine, with much
Placer mining is the mining of stream bed deposits for minerals. This may be done by various surface excavating equipment or tunnelling equipment. Placer mining is used for precious metal deposits and gemstones, both of which are found in alluvial deposits—deposits of sand and gravel in modern or ancient stream beds, or glacial deposits; the metal or gemstones, having been moved by stream flow from an original source such as a vein, are only a minuscule portion of the total deposit. Since gems and heavy metals like gold are denser than sand, they tend to accumulate at the base of placer deposits, it is important to note that placer deposits can be as young as a few years old, such as the Canadian Queen Charlotte beach gold placer deposits, or billions of years old like the Elliott Lake uranium paleoplacer within the Huronian Supergroup in Canada. The containing material in an alluvial placer mine may be too loose to safely mine by tunnelling, though it is possible where the ground is permanently frozen.
Where water under pressure is available, it may be used to mine and separate the precious material from the deposit, a method known as hydraulic mining, hydraulic sluicing or hydraulicking. The word placer derives from the Spanish placer, meaning shoal or alluvial/sand deposit, from Catalan placer, from plassa, from Medieval Latin placea the origin word for "place" and "plaza" in English; the word in Spanish is thus derived from placea and refers directly to an alluvial or glacial deposit of sand or gravel. Placers supplied most of the gold for a large part of the ancient world. Hydraulic mining methods such as hushing were used by the Romans across their empire, but in the gold fields of northern Spain after its conquest by Augustus in 25 BC. One of the largest sites was at Las Médulas, where seven 30 mile long aqueducts were used to work the alluvial gold deposits through the first century AD. In North America, placer mining was famous in the context of several gold rushes the California Gold Rush and the Colorado Gold Rush, the Fraser Canyon Gold Rush and the Klondike Gold Rush.
Placer mining continues in many areas of the world as a source of diamonds, industrial minerals and metals, platinum, of gold. An area well protected from the flow of water is a great location to find gold. Gold is dense and is found in a stream bed. Many different gold deposits are dealt with in different ways. Placer deposits attract many prospectors because their costs are low. There are many different places gold could be placed, such as a residual, a bench deposit. Residual deposits are more common where there has been weathering on rocks and where there hasn’t been water, they are deposits which have not been been moved. The residual lies at the site of the lode; this type of deposit undergoes rock weathering. Alluvial or eluvial deposits sometimes have the largest gold deposit and are common; this deposit is created when a force of nature moves or washes the gold away, but it doesn’t go into a stream bed. It contains pieces of ore. Alluvial deposits are the most common type of placer gold; this type of deposit occurs in valleys.
Bench deposits are created. Gold accumulations in an old stream bed that are high are called bench deposits, they can be found on higher slopes. Dry stream beds can be situated far from other water sources and can sometimes be found on mountain tops. Today, many miners focus their activities on bench deposits. A number of methods are used to mine placer gold and gems, both in terms of extracting the minerals from the ground, separating it from the non-gold or non-gems; the simplest technique to extract gold from placer ore is panning. This technique has been dated back to at least the Roman Empire. In panning, some mined ore is placed in a large metal or plastic pan, combined with a generous amount of water, agitated so that the gold particles, being of higher density than the other material, settle to the bottom of the pan; the lighter gangue material such as sand and gravel are washed over the side of the pan, leaving the gold behind. Once a placer deposit is located by gold panning, the miner shifts to equipment that can treat volumes of sand and gravel more and efficiently.
Gold panning was used on its own during the California gold rush, however it is now used for profit since an expert gold prospector can only process one cubic yard of material for every 10 hours of work. A rocker box is capable of greater volume than a gold pan, however its production is still limited when compared to other methods of placer mining, it is only capable of processing about 4 yards of gravel a day. It is more portable and requires less infrastructure than a sluice box, being fed not by a sluice but by hand; the box sits on rockers, which when rocked separates out the gold, the practice was referred to as "rocking the golden baby". A typical rocker box is 42 inches long, 16 inches wide and 12 inches long with a removable tray towards the top, where gold is placed; the rocker was used throughout North America during the early gold rush, but its popularity diminished as other meth
California is a state in the Pacific Region of the United States. With 39.6 million residents, California is the most populous U. S. the third-largest by area. The state capital is Sacramento; the Greater Los Angeles Area and the San Francisco Bay Area are the nation's second and fifth most populous urban regions, with 18.7 million and 9.7 million residents respectively. Los Angeles is California's most populous city, the country's second most populous, after New York City. California has the nation's most populous county, Los Angeles County, its largest county by area, San Bernardino County; the City and County of San Francisco is both the country's second-most densely populated major city after New York City and the fifth-most densely populated county, behind only four of the five New York City boroughs. California's $3.0 trillion economy is larger than that of any other state, larger than those of Texas and Florida combined, the largest sub-national economy in the world. If it were a country, California would be the 5th largest economy in the world, the 36th most populous as of 2017.
The Greater Los Angeles Area and the San Francisco Bay Area are the nation's second- and third-largest urban economies, after the New York metropolitan area. The San Francisco Bay Area PSA had the nation's highest GDP per capita in 2017 among large PSAs, is home to three of the world's ten largest companies by market capitalization and four of the world's ten richest people. California is considered a global trendsetter in popular culture, innovation and politics, it is considered the origin of the American film industry, the hippie counterculture, fast food, the Internet, the personal computer, among others. The San Francisco Bay Area and the Greater Los Angeles Area are seen as global centers of the technology and entertainment industries, respectively. California has a diverse economy: 58% of the state's economy is centered on finance, real estate services and professional, scientific and technical business services. Although it accounts for only 1.5% of the state's economy, California's agriculture industry has the highest output of any U.
S. state. California is bordered by Oregon to the north and Arizona to the east, the Mexican state of Baja California to the south; the state's diverse geography ranges from the Pacific Coast in the west to the Sierra Nevada mountain range in the east, from the redwood–Douglas fir forests in the northwest to the Mojave Desert in the southeast. The Central Valley, a major agricultural area, dominates the state's center. Although California is well-known for its warm Mediterranean climate, the large size of the state results in climates that vary from moist temperate rainforest in the north to arid desert in the interior, as well as snowy alpine in the mountains. Over time and wildfires have become more pervasive features. What is now California was first settled by various Native Californian tribes before being explored by a number of European expeditions during the 16th and 17th centuries; the Spanish Empire claimed it as part of Alta California in their New Spain colony. The area became a part of Mexico in 1821 following its successful war for independence but was ceded to the United States in 1848 after the Mexican–American War.
The western portion of Alta California was organized and admitted as the 31st state on September 9, 1850. The California Gold Rush starting in 1848 led to dramatic social and demographic changes, with large-scale emigration from the east and abroad with an accompanying economic boom; the word California referred to the Baja California Peninsula of Mexico. The name derived from the mythical island California in the fictional story of Queen Calafia, as recorded in a 1510 work The Adventures of Esplandián by Garci Rodríguez de Montalvo; this work was the fifth in a popular Spanish chivalric romance series that began with Amadis de Gaula. Queen Calafia's kingdom was said to be a remote land rich in gold and pearls, inhabited by beautiful black women who wore gold armor and lived like Amazons, as well as griffins and other strange beasts. In the fictional paradise, the ruler Queen Calafia fought alongside Muslims and her name may have been chosen to echo the title of a Muslim leader, the Caliph. It's possible.
Know ye that at the right hand of the Indies there is an island called California close to that part of the Terrestrial Paradise, inhabited by black women without a single man among them, they lived in the manner of Amazons. They were robust of body with great virtue; the island itself is one of the wildest in the world on account of the craggy rocks. Shortened forms of the state's name include CA, Cal. Calif. and US-CA. Settled by successive waves of arrivals during the last 10,000 years, California was one of the most culturally and linguistically diverse areas in pre-Columbian North America. Various estimates of the native population range from 100,000 to 300,000; the Indigenous peoples of California included more than 70 distinct groups of Native Americans, ranging from large, settled populations living on the coast to groups in the interior. California groups were diverse in their political organization with bands, villages, on the resource-rich coasts, large chiefdoms, such as the Chumash and Salinan.
Trade, intermarriage a
In geology, bedrock is the lithified rock that lies under a loose softer material called regolith within the surface of the crust of the Earth or other terrestrial planets. Bedrock refers to the substructure composed of hard rock exposed or buried at the earths surface, an exposed portion of bedrock is called an outcrop. Bedrock may have various chemical and mineralogical compositions and can be igneous, metamorphic or sedimentary in origin; the bedrock may be overlain by weathered regolith which includes soil and the subsoil. The surface of the bedrock beneath the soil cover is known as rockhead in engineering geology, its identification by digging, drilling or geophysical methods is an important task in most civil engineering projects. Superficial deposits can be thick, such that the bedrock lies hundreds of meters below the surface. Bedrock when exposed or within the subsurface may experience weathering and erosion by external factors. Weathering may be physical or chemical and alters the structure of the rock and may cause it to erode and or alter over time based on the interactions between the mineralogy and its interactions.
Bedrock may experience subsurface weathering at its upper boundary, forming saprolite. A geologic map of an area will show the distribution of differing bedrock types, rock that would be exposed at the surface if all soil or other superficial deposits were removed. Geology – The study of the composition, physical properties, history of Earth's components, the processes by which they are shaped. Outcrop Regolith – A layer of loose, heterogeneous superficial deposits covering solid rock Soil – mixture of organic matter, gases and organisms that together support life Weathering – Breaking down of rocks and minerals as well as artificial materials through contact with the Earth's atmosphere and waters Rafferty, John P. "Bedrock GEOLOGY". Encyclopedia Britannica. Encyclopedia Britannica. Retrieved 1 April 2019. Harris, The Gale Encyclopedia of Science. Ed. K. Lee Lerner and Brenda Wilmoth Lerner. Vol. 1. 5th ed. Farmington Hills, MI: Gale, 2014. P515-516. Media related to Bedrock at Wikimedia Commons