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66-542: Missiquoi is also the name of a 17th-century Abenaki village in northern Vermont, for which the sub-tribe was named. The name Missisquoi comes from mazipskoiak meaning "flint people," which comes from mazipskoik or "at the flint," meaning a chert quarry near what is now Swanton, Vermont . It's also spelled Missiassik or Masipskoik a word that means "where there are many big rocks or boulder" in Abenaki . Prior to European contact, some Western Abenaki founded villages at

132-659: A Hertzian cone when struck with sufficient force. This results in conchoidal fractures, a characteristic of all minerals with no cleavage planes. In this kind of fracture, a cone of force propagates through the material from the point of impact, eventually removing a full or partial cone, like when a plate-glass window is struck by a small object such as an air gun projectile. The partial Hertzian cones produced during lithic reduction are called flakes , and exhibit features characteristic of this sort of breakage, including striking platforms , bulbs of force , and occasionally eraillures , which are small secondary flakes detached from

198-426: A hydride ion . Reductants in chemistry are very diverse. Electropositive elemental metals , such as lithium , sodium , magnesium , iron , zinc , and aluminium , are good reducing agents. These metals donate electrons relatively readily. Hydride transfer reagents , such as NaBH 4 and LiAlH 4 , reduce by atom transfer: they transfer the equivalent of hydride or H . These reagents are widely used in

264-448: A fraction of a micron to 20 microns, but most typically 8 to 10 microns. Chalcedony is a microfibrous variety of quartz, consisting of radiating bundles of very thin crystals about 100 microns long. Megaquartz is composed of equidimensional grains over 20 microns in size. Most chert is microcrystalline quartz with minor chalcedony and sometimes opal , but cherts range from nearly pure opal to nearly pure quartz chert. However, little opal

330-411: A gas. Later, scientists realized that the metal atom gains electrons in this process. The meaning of reduction then became generalized to include all processes involving a gain of electrons. Reducing equivalent refers to chemical species which transfer the equivalent of one electron in redox reactions. The term is common in biochemistry . A reducing equivalent can be an electron or a hydrogen atom as

396-413: A microcrystalline form of silica composed mostly of bladed crystals of cristobalite and tridymite . Much opal-CT takes the form of lepispheres , which are clusters of bladed crystals about 10 microns in diameter. Opal-CT in turn transforms to microquartz. In deep ocean water, the transition to opal-CT occurs at a temperature of about 45 °C (113 °F) while the transition to microquartz occurs at

462-459: A more easily corroded " sacrificial anode " to act as the anode . The sacrificial metal, instead of the protected metal, then corrodes. A common application of cathodic protection is in galvanized steel, in which a sacrificial zinc coating on steel parts protects them from rust. Oxidation is used in a wide variety of industries, such as in the production of cleaning products and oxidizing ammonia to produce nitric acid . Redox reactions are

528-413: A redox reaction that takes place in a cell, the potential difference is: However, the potential of the reaction at the anode is sometimes expressed as an oxidation potential : The oxidation potential is a measure of the tendency of the reducing agent to be oxidized but does not represent the physical potential at an electrode. With this notation, the cell voltage equation is written with a plus sign In

594-418: A source of dissolved silica, but they are sometimes found cutting across bedding surfaces, where the chert fills fossil burrows , fluid escape structures , or fractures. Nodules under a few centimeters in size tend to be egg-shaped, while larger nodules form irregular bodies with knobby surfaces. The outer few centimeters of large nodules may show desiccation cracks with secondary chert, which likely formed at

660-506: A spark that ignites a small reservoir containing black powder , discharging the firearm. Cherts can cause several problems when used as concrete aggregates. Deeply weathered chert develops surface pop-outs when used in concrete that undergoes freezing and thawing because of the high porosity of weathered chert. The other concern is that certain cherts undergo an alkali-silica reaction with high-alkali cements. This reaction leads to cracking and expansion of concrete and ultimately to failure of

726-870: A temperature of about 80 °C (176 °F). However, the transition temperature varies considerably, and the transition is hastened by the presence of magnesium hydroxide , which provides a nucleus for the recrystallization. Megaquartz forms at elevated temperatures typical of metamorphism . There is evidence that the variety of chert called porcelainite , which is characterized by a high content of opal-CT, recrystallizes at very shallow depths. The Caballos Novaculite of Texas also shows signs of very shallow water deposition, including shallow water sedimentary structures and evaporite pseudomorphs , which are casts of crystals of soluble minerals that could have formed only in near-surface conditions. This novaculate appears to have formed by replacement of carbonate fecal pellets by chert. Bedded cherts can be further subdivided by

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792-408: A whole reaction. In electrochemical reactions the oxidation and reduction processes do occur simultaneously but are separated in space. Oxidation originally implied a reaction with oxygen to form an oxide. Later, the term was expanded to encompass substances that accomplished chemical reactions similar to those of oxygen. Ultimately, the meaning was generalized to include all processes involving

858-429: Is also called an electron acceptor . Oxidants are usually chemical substances with elements in high oxidation states (e.g., N 2 O 4 , MnO 4 , CrO 3 , Cr 2 O 7 , OsO 4 ), or else highly electronegative elements (e.g. O 2 , F 2 , Cl 2 , Br 2 , I 2 ) that can gain extra electrons by oxidizing another substance. Oxidizers are oxidants, but

924-447: Is also known as its reduction potential ( E red ), or potential when the half-reaction takes place at a cathode. The reduction potential is a measure of the tendency of the oxidizing agent to be reduced. Its value is zero for H + e → 1 ⁄ 2 H 2 by definition, positive for oxidizing agents stronger than H (e.g., +2.866 V for F 2 ) and negative for oxidizing agents that are weaker than H (e.g., −0.763V for Zn ). For

990-518: Is based in Swanton, Vermont . The group applied for but was denied federal recognition as a Native American tribe in 2007. The summary of the proposed finding (PF) stated that "The SSA petitioner claims to have descended as a group mainly from a Western Abenaki Indian tribe, most specifically, the Missisquoi Indians" and went on to state: "However, the available evidence does not demonstrate that

1056-465: Is dependent on these ratios. Redox mechanisms also control some cellular processes. Redox proteins and their genes must be co-located for redox regulation according to the CoRR hypothesis for the function of DNA in mitochondria and chloroplasts . Wide varieties of aromatic compounds are enzymatically reduced to form free radicals that contain one more electron than their parent compounds. In general,

1122-865: Is devoid of any fossils. Chert varies greatly in color, from white to black, but is most often found as gray, brown, grayish brown and light green to rusty red and occasionally as dark green. Its color is an expression of trace elements present in the rock. Both red and green are most often related to traces of iron in its oxidized and reduced forms, respectively. In petrology , the term "chert" refers generally to all chemically precipitated sedimentary rocks composed primarily of microcrystalline , cryptocrystalline and microfibrous silica . Most cherts are nearly pure silica, with less than 5% other minerals (mostly calcite , dolomite , clay minerals , hematite , and organic matter.) However, cherts range from very pure cherts with over 99% silica content to impure nodular cherts with less than 65% silica content. Aluminium

1188-418: Is far below saturation, indicating that silica cannot normally be precipitated from seawater through inorganic processes. The silica is instead extracted from seawater by living organisms, such as diatoms, radiolarians, and glass sponges, which can efficiently extract silica even from very unsaturated water, and which are estimated to presently produce 12 cubic kilometers (2.9 cu mi) of opal per year in

1254-885: Is little in the carbonate buildup zone itself. This may reflect dissolution of opal where carbonate is being actively deposited, a lack of siliceous organisms in these environments, or removal of siliceous skeletons by strong currents that redeposit the siliceous material in the deep basin. The silica in nodular chert likely precipitates as opal-A, based on internal banding in nodules, and may recrystallize directly to microquartz without first recrystallizing to opal-CT. Some nodular chert may precipitate directly as microquartz, due to low levels of supersaturation of silica. The banded iron formations of Precambrian age are composed of alternating layers of chert and iron oxides . Nonmarine cherts may form in saline alkaline lakes as thin lenses or nodules showing sedimentary structures suggestive of evaporite origin. Such cherts are forming today in

1320-432: Is mined as its magnetite (Fe 3 O 4 ). Titanium is mined as its dioxide, usually in the form of rutile (TiO 2 ). These oxides must be reduced to obtain the corresponding metals, often achieved by heating these oxides with carbon or carbon monoxide as reducing agents. Blast furnaces are the reactors where iron oxides and coke (a form of carbon) are combined to produce molten iron. The main chemical reaction producing

1386-505: Is not the reverse of the redox reaction in cellular respiration: Biological energy is frequently stored and released using redox reactions. Photosynthesis involves the reduction of carbon dioxide into sugars and the oxidation of water into molecular oxygen. The reverse reaction, respiration, oxidizes sugars to produce carbon dioxide and water. As intermediate steps, the reduced carbon compounds are used to reduce nicotinamide adenine dinucleotide (NAD ) to NADH, which then contributes to

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1452-485: Is of only modest economic importance today as a source of silica (quartz sand being much more important.) However, chert deposits may be associated with valuable deposits of iron , uranium , manganese , phosphorite , and petroleum . In prehistoric times, chert was often used as a raw material for the construction of stone tools . Like obsidian , as well as some rhyolites , felsites , quartzites , and other tool stones used in lithic reduction , chert fractures in

1518-512: Is over 60 million years old. Opaline chert often contains visible fossils of diatoms , radiolarians , and glass sponge spicules . Chert is found in settings as diverse as hot spring deposits ( siliceous sinter ), banded iron formation ( jaspilite ), or alkaline lakes . However, most chert is found either as bedded chert or as nodular chert . Bedded chert is more common in Precambrian beds, but nodular chert became more common in

1584-435: Is the most abundant minor element, followed by iron and manganese or potassium , sodium , and calcium . Extracrystalline water (tiny inclusions of water within and around the quartz grains) make up less than 1% of most cherts. The Folk classification divides chert into three textural categories. Granular microquartz is the component of chert consisting of roughly equidimensional quartz grains, ranging in size from

1650-418: Is typically composed of the petrified remains of siliceous ooze , the biogenic sediment that covers large areas of the deep ocean floor, and which contains the silicon skeletal remains of diatoms , silicoflagellates , and radiolarians . Precambrian cherts are notable for the presence of fossil cyanobacteria . In addition to microfossils , chert occasionally contains macrofossils . However, some chert

1716-419: Is uncertain, but they may form from fossil remains that are completely dissolved in fluids that then migrate to precipitate their silica load in a nearby bed. Eolian quartz has also been suggested as a source of silica for chert beds. Precambrian bedded cherts are common, making up 15% of middle Precambrian sedimentary rock, and may have been deposited nonbiologically in oceans more saturated in silica than

1782-506: Is usually black to green in color, and the full sequence of beds may be several hundred meters thick. The shale is typically black shale, sometimes with pyrite , indicating deposition in an anoxic environment. Bedded chert is most often found in association with turbidites , deep water limestone , submarine volcanic rock , ophiolites , and mélanges on active margins of tectonic plates . Sedimentary structures are rare in bedded cherts. The typically high purity of bedded chert, like

1848-648: The Cretaceous . Diatoms were the dominant siliceous organism responsible for extracting silica from seawater from the Jurassic and later. Radiolarite consists mostly of remains of radiolarians. When the remains are well-cemented with silica, it is known as radiolarian chert . Many show evidence of a deep-water origin, but some appear to have formed in water as shallow as 200 meters (660 ft), perhaps in shelf seas where upwelling of nutrient-rich deep ocean water support high organic productivity. Radiolarians dominated

1914-957: The Merrimack River and the Champlain Valley, moved north to the Saint-François River in Quebec, Canada . There they joined the local Odanak community of Abenaki people. After enduring French and English colonists, the Missisquoi withdrew from areas of conflict during the American Revolutionary War . Linguist and historian Gordon M. Day wrote, "After this war, the Western Abenakis did not return to any of their former locations in force but rather united or reunited with their brethren at Saint Francis." Some held on to land claims in

1980-589: The Phanerozoic as the total volume of chert in the rock record diminished. Bedded chert is rare after the early Mesozoic . Chert became moderately abundant during the Devonian and Carboniferous and again became moderately abundant from the Jurassic to the present. Bedded chert, also known as ribbon chert, takes the form of thinly bedded layers (a few centimeters to a meter in thickness ) of nearly pure chert separated by very thin layers of silica-rich shale . It

2046-422: The oxidation states of the reactants change. Oxidation is the loss of electrons or an increase in the oxidation state, while reduction is the gain of electrons or a decrease in the oxidation state. The oxidation and reduction processes occur simultaneously in the chemical reaction. There are two classes of redox reactions: "Redox" is a portmanteau of the words "REDuction" and "OXidation." The term "redox"

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2112-721: The United States and even collected rent. In 1805, the British Crown deeded lands near Durham, Quebec, to Abenaki people who fled the American Revolutionary War; these lands became the Durham Reserve. By 1850, this group became part of the large St. Francis village (Odanak). The St. Francis-Sokoki Band of the Abenaki Nation of Missisquoi is state-recognized by Vermont and claim to be Missiquoi descendants. The group

2178-403: The alkaline Lake T'oo'dichi'. Chert may also form from replacement of calcrete in fossil soils ( paleosols ) by silica dissolved from overlying volcanic ash beds. The cryptocrystalline nature of chert, combined with its above average ability to resist weathering, recrystallization and metamorphism has made it an ideal rock for preservation of early life forms. For example: Chert

2244-538: The alkaline lakes of the East African Rift Valley . These lakes are characterized by sodium carbonate brines with very high pH that can contain as much as 2700 ppm silica. Episodes of runoff of fresh water into the lakes lowers the pH and precipitates the unusual sodium silicate minerals magadiite or kenyaite , After burial and diagenesis , these are altered to Magadi-type chert. The Morrison Formation contains Magadi-type chert that may have formed in

2310-443: The copper sulfate solution, thus liberating free copper metal. The reaction is spontaneous and releases 213 kJ per 65 g of zinc. The ionic equation for this reaction is: As two half-reactions , it is seen that the zinc is oxidized: And the copper is reduced: A disproportionation reaction is one in which a single substance is both oxidized and reduced. For example, thiosulfate ion with sulfur in oxidation state +2 can react in

2376-479: The creation of a proton gradient , which drives the synthesis of adenosine triphosphate (ATP) and is maintained by the reduction of oxygen. In animal cells, mitochondria perform similar functions. Free radical reactions are redox reactions that occur as part of homeostasis and killing microorganisms . In these reactions, an electron detaches from a molecule and then re-attaches almost instantly. Free radicals are part of redox molecules and can become harmful to

2442-408: The early 1970's'...." Chert Chert ( / tʃ ɜːr t / ) is a hard, fine-grained sedimentary rock composed of microcrystalline or cryptocrystalline quartz , the mineral form of silicon dioxide (SiO 2 ). Chert is characteristically of biological origin, but may also occur inorganically as a chemical precipitate or a diagenetic replacement, as in petrified wood . Chert

2508-476: The electron donor is any of a wide variety of flavoenzymes and their coenzymes . Once formed, these anion free radicals reduce molecular oxygen to superoxide and regenerate the unchanged parent compound. The net reaction is the oxidation of the flavoenzyme's coenzymes and the reduction of molecular oxygen to form superoxide. This catalytic behavior has been described as a futile cycle or redox cycling. Minerals are generally oxidized derivatives of metals. Iron

2574-415: The electrons cancel: The protons and fluoride combine to form hydrogen fluoride in a non-redox reaction: The overall reaction is: In this type of reaction, a metal atom in a compound or solution is replaced by an atom of another metal. For example, copper is deposited when zinc metal is placed in a copper(II) sulfate solution: In the above reaction, zinc metal displaces the copper(II) ion from

2640-446: The environment. Cellular respiration , for instance, is the oxidation of glucose (C 6 H 12 O 6 ) to CO 2 and the reduction of oxygen to water . The summary equation for cellular respiration is: The process of cellular respiration also depends heavily on the reduction of NAD to NADH and the reverse reaction (the oxidation of NADH to NAD ). Photosynthesis and cellular respiration are complementary, but photosynthesis

2706-553: The extraction of silica from seawater prior to the Jurassic. Spicularite is chert composed of spicules of glass sponges and other invertebrates. When densely cemented, it is known as spicular chert . They are found in association with glauconite -rich sandstone , black shale , clay -rich limestone , phosphorites , and other nonvolcanic rocks typical of water a few hundred meters deep. Some bedded cherts appear devoid of fossils even under close microscopic examination. Their origin

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2772-419: The flake's bulb of force. When a chert stone is struck against an iron-bearing surface, sparks result. This makes chert an excellent tool for starting fires, and both flint and common chert were used in various types of fire-starting tools, such as tinderboxes , throughout history. A primary historic use of common chert and flint was for flintlock firearms , in which the chert striking a metal plate produces

2838-660: The foundation of electrochemical cells, which can generate electrical energy or support electrosynthesis . Metal ores often contain metals in oxidized states, such as oxides or sulfides, from which the pure metals are extracted by smelting at high temperatures in the presence of a reducing agent. The process of electroplating uses redox reactions to coat objects with a thin layer of a material, as in chrome-plated automotive parts, silver plating cutlery , galvanization and gold-plated jewelry . Many essential biological processes involve redox reactions. Before some of these processes can begin, iron must be assimilated from

2904-490: The high purity of other chemically precipitated rock, points to deposition in areas where there is little influx of detrital sediments (such as river water laden with silt and clay particles.) Such impurities as are present include authigenic pyrite and hematite, formed in the sediments after they were deposited, in addition to traces of detrital minerals. Seawater typically contains between 0.01 and 11 parts per million (ppm) of silica, with around 1 ppm being typical. This

2970-413: The human body if they do not reattach to the redox molecule or an antioxidant . The term redox state is often used to describe the balance of GSH/GSSG , NAD /NADH and NADP /NADPH in a biological system such as a cell or organ . The redox state is reflected in the balance of several sets of metabolites (e.g., lactate and pyruvate , beta-hydroxybutyrate and acetoacetate ), whose interconversion

3036-473: The kinds of organisms that produced the silica skeletons. Diatomaceous chert consists of beds and lenses of diatomite which were converted during diagenesis into dense, hard chert. Beds of marine diatomaceous chert comprising strata several hundred meters thick have been reported from sedimentary sequences such as the Miocene Monterey Formation of California and occur in rocks as old as

3102-413: The loss of electrons or the increase in the oxidation state of a chemical species. Substances that have the ability to oxidize other substances (cause them to lose electrons) are said to be oxidative or oxidizing, and are known as oxidizing agents , oxidants, or oxidizers. The oxidant removes electrons from another substance, and is thus itself reduced. Because it "accepts" electrons, the oxidizing agent

3168-434: The material. There are numerous varieties of chert, classified based on their visible, microscopic and physical characteristics. Examples are: Other lesser used archaic terms for chert are firestone and silex. Redox Redox ( / ˈ r ɛ d ɒ k s / RED -oks , / ˈ r iː d ɒ k s / REE -doks , reduction–oxidation or oxidation–reduction ) is a type of chemical reaction in which

3234-606: The modern ocean. The high degree of silica saturation was due either to intense volcanic activity or to the lack of modern organisms that remove silica from seawater. Nodular chert is most common in limestone but may also be found in shales and sandstones. It is less common in dolomite . Nodular chert in carbonate rocks is found as oval to irregular nodules . These vary in size from powdery quartz particles to nodules several meters in size. The nodules are most typically along bedding planes or stylolite (dissolution) surfaces, where fossil organisms tended to accumulate and provided

3300-492: The molten iron is: Electron transfer reactions are central to myriad processes and properties in soils, and redox potential , quantified as Eh (platinum electrode potential ( voltage ) relative to the standard hydrogen electrode) or pe (analogous to pH as -log electron activity), is a master variable, along with pH, that controls and is governed by chemical reactions and biological processes. Early theoretical research with applications to flooded soils and paddy rice production

3366-677: The mouth of the Missisquoi River . By the 17th century, Western Abenaki from across Lake Champlain consolidated into the main village at Missisquoi in northern Vermont , so historians began to use the term "Missisquoi tribe" for all Champlain Valley Abenakis. The Sokoki people, who had lived along the Connecticut River , founded Odanak, also known as the village of St. Francis in Quebec. The Western Abenakis, including those living along

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3432-424: The ocean bottom and are buried, forming siliceous ooze that is 30% to 60% silica. Thus, bedded cherts are typically composed mostly of fossil remains of organisms that secrete silica skeletons, which are usually altered by solution and recrystallization. The skeletons of these organisms are composed of opal-A, an amorphous form of silica, lacking long-range crystal structure. This is gradually transformed to opal-CT,

3498-424: The oxidant or oxidizing agent gains electrons and is reduced. The pair of an oxidizing and reducing agent that is involved in a particular reaction is called a redox pair. A redox couple is a reducing species and its corresponding oxidizing form, e.g., Fe / Fe .The oxidation alone and the reduction alone are each called a half-reaction because two half-reactions always occur together to form

3564-546: The petitioner or its claimed ancestors descended from the St. Francis Indians of Quebec, a Missiquoi Abenaki entity in Vermont, any other Western Abenaki group, or an Indian entity from New England or Canada. Instead, the PF concluded that the petitioner is a collection of individuals of claimed but undemonstrated Indian ancestry 'with little or no social or historical connection with each other before

3630-404: The presence of acid to form elemental sulfur (oxidation state 0) and sulfur dioxide (oxidation state +4). Thus one sulfur atom is reduced from +2 to 0, while the other is oxidized from +2 to +4. Cathodic protection is a technique used to control the corrosion of a metal surface by making it the cathode of an electrochemical cell . A simple method of protection connects protected metal to

3696-538: The reaction between hydrogen and fluorine , hydrogen is being oxidized and fluorine is being reduced: This spontaneous reaction releases 542 kJ per 2 g of hydrogen because the H-F bond is much stronger than the F-F bond. This reaction can be analyzed as two half-reactions . The oxidation reaction converts hydrogen to protons : The reduction reaction converts fluorine to the fluoride anion: The half-reactions are combined so that

3762-410: The reducing agent is also called an electron donor . Electron donors can also form charge transfer complexes with electron acceptors. The word reduction originally referred to the loss in weight upon heating a metallic ore such as a metal oxide to extract the metal. In other words, ore was "reduced" to metal. Antoine Lavoisier demonstrated that this loss of weight was due to the loss of oxygen as

3828-494: The reduction of carbonyl compounds to alcohols . A related method of reduction involves the use of hydrogen gas (H 2 ) as sources of H atoms. The electrochemist John Bockris proposed the words electronation and de-electronation to describe reduction and oxidation processes, respectively, when they occur at electrodes . These words are analogous to protonation and deprotonation . They have not been widely adopted by chemists worldwide, although IUPAC has recognized

3894-411: The same time as the nodule. Calcareous fossils are occasionally present that have been completely silicified. Where chert occurs in chalk or marl , it is usually called flint . Nodular chert is often dark in color. It can have a white weathering rind that is known in archaeology as cortex . Most chert nodules have textures suggesting they were formed by diagenetic replacement, where silica

3960-437: The term is mainly reserved for sources of oxygen, particularly in the context of explosions. Nitric acid is a strong oxidizer. Substances that have the ability to reduce other substances (cause them to gain electrons) are said to be reductive or reducing and are known as reducing agents , reductants, or reducers. The reductant transfers electrons to another substance and is thus itself oxidized. Because it donates electrons,

4026-658: The terms electronation and de-electronation. Redox reactions can occur slowly, as in the formation of rust , or rapidly, as in the case of burning fuel . Electron transfer reactions are generally fast, occurring within the time of mixing. The mechanisms of atom-transfer reactions are highly variable because many kinds of atoms can be transferred. Such reactions can also be quite complex, involving many steps. The mechanisms of electron-transfer reactions occur by two distinct pathways, inner sphere electron transfer and outer sphere electron transfer . Analysis of bond energies and ionization energies in water allows calculation of

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4092-446: The thermodynamic aspects of redox reactions. Each half-reaction has a standard electrode potential ( E cell ), which is equal to the potential difference or voltage at equilibrium under standard conditions of an electrochemical cell in which the cathode reaction is the half-reaction considered, and the anode is a standard hydrogen electrode where hydrogen is oxidized: The electrode potential of each half-reaction

4158-408: The world's oceans. Diatoms can double their numbers eight times a day under ideal conditions (though doubling once per day is more typical in normal seawater) and can extract silica from water with as little as 0.1 ppm silica. The organisms protect their skeletons from dissolution by "armoring" them with metal ions. Once the organisms die, their skeletons will quickly dissolve unless they accumulate on

4224-571: Was deposited in place of calcium carbonate or clay minerals . This may have taken place where meteoric water (water derived from snow or rain) mixed with saltwater in the sediment beds, where carbon dioxide was trapped, producing an environment supersaturated with silica and undersaturated with calcium carbonate. Nodular chert is particularly common in continental shelf environments. In the Permian Basin (North America) , chert nodules and chertified fossils are abundant in basin limestones, but there

4290-409: Was first used in 1928. Oxidation is a process in which a substance loses electrons. Reduction is a process in which a substance gains electrons. The processes of oxidation and reduction occur simultaneously and cannot occur independently. In redox processes, the reductant transfers electrons to the oxidant. Thus, in the reaction, the reductant or reducing agent loses electrons and is oxidized, and

4356-433: Was seminal for subsequent work on thermodynamic aspects of redox and plant root growth in soils. Later work built on this foundation, and expanded it for understanding redox reactions related to heavy metal oxidation state changes, pedogenesis and morphology, organic compound degradation and formation, free radical chemistry, wetland delineation, soil remediation , and various methodological approaches for characterizing

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