Iron

One element of the medical approach is a specific chelating agent called deferoxamine, used to bind and expel excess iron from the body in case of iron toxicity. See also Ivory carving.. The medical management of iron toxicity is complex. So-called hornbill ivory, derived from a bird, is not true ivory but resembles it in some ways. Blood donors are at special risk of low iron levels and are often recommended to supplement their iron intake. [1]. For this reason, people should not take iron supplements unless they suffer from iron deficiency and have consulted a doctor. It is sometimes called vegetable ivory, or tagua, and is the seed endosperm of the ivory nut palm commonly found in coastal rainforests of Ecuador and Peru.

Iron overload disorders require a genetic inability to regulate iron uptake; however, many people have a genetic susceptibility to iron overload without realizing it and without knowing a family history of the problem. A species of hard nut is gaining popularity as a replacement for ivory, although its size limits its usability. If iron intake is excessive iron overload disorders can sometimes result, such as hemochromatosis. Mammoth ivory is used today to make handcrafted knives and similar implements. For children under fourteen years old the UL is 40 mg/day. Trade in the ivory from the tusks of dead mammoths has occurred for 300 years and continues to be legal. The DRI lists the Tolerable Upper Intake Level (UL) for adults as 45 mg/day. Kenya, which saw its elephant populations plummet in the decade preceding the 1989 ban, claims that legalizing ivory trade anywhere in Africa will endanger elephants everywhere in Africa as poachers would attempt to launder their illegal ivory with legal stockpiles.

Humans experience iron toxicity above 20 milligrams of iron for every kilogram of weight, and 60 milligrams per kilogram is a lethal dose.[3] Over-consumption of iron, often the result of children eating large quantitities of ferrous sulfate tablets intended for adult consumption, is the most common toxicological cause of death in children under six. Yet, a 1999 study done by Oxford University found that less than one percent of the five-hundred million US dollars ivory sales generate ever reach Africans; most of it goes to middlemen and vendors, so the effectiveness of the policy is in question. This can cause serious problems, including the potential of death from overdose, and long-term organ damage in survivors. In 2002 the United Nations partially lifted the ban on ivory trade, allowing a few countries to export certain amounts of ivory. Once there, it causes damage to cells in the heart, liver and elsewhere. Many African countries including Zimbabwe and South Africa claim that ivory trade is necessary—both to stimulate their economies and reduce elephant populations which are allegedly harming the environment. However, too much ingested iron can damage the cells of the gastrointestinal tract directly, and may enter the bloodstream by damaging the cells that would otherwise regulate its entry. Since the worldwide ivory trade ban in 1989 there have been ups and downs in elephant populations, and ivory trade as bans have been placed and lifted.

Iron uptake is tightly regulated by the human body, which has no physiologic means of excreting iron and regulates iron solely by regulating uptake. Much of the decline in population is due to poachers during and before the 1980s. In excess, uncontrollable quantities of free radicals are produced. Due to the rapid decline in the populations of the animals that produce it, the importation and sale of ivory in many countries is banned or severely restricted. Iron becomes toxic when it exceeds the amount of transferrin needed to bind free iron. Additionally, warthog tusks, and teeth from sperm whales, orcas and hippos can also be scrimshawed or superficially carved, thus retaining their morphologically recognizable shapes. Excessive iron is toxic to humans, because excess ferrous iron reacts with peroxides in the body, producing free radicals. A small example of modern carved ivory objects are small statuary, netsukes, jewelry, flatware handles, furniture inlays, and piano keys.

Also note the section below on precautions. Tooth and tusk ivory can be carved into an almost infinite variety of shapes and objects. The RDA for iron varies considerably based on the age, gender, and source of dietary iron (heme-based iron has higher bioavailability)[2]. The North African elephant population was probably reduced to extinction, due to the demand for ivory in the Classical world. Iron provided by dietary supplements is often found as Iron (II) fumarate. Ivory was often used to form the whites of the eyes of statues. Good sources of dietary iron include meat, fish, poultry, lentils, beans, leaf vegetables, tofu, chickpeas, black-eyed pea, strawberries and farina. Both the Greek and Roman civilizations used large quantities of ivory to make high value works of art, precious religious objects, and decorative boxes for costly objects.

A lengthier article on the system of human iron regulation can be found in the article on human iron metabolism. Paleolithic Cro-Magnon man, during the late stages of the ice age, were the first to carve in ivory (mammoth tusks). [1]. The three dimensional configuration of the dentinal tubules is under genetic control and is therefore a characteristic unique to the order. There it gets by an as yet unknown mechanism incorporated into target proteins. Their length is dictated by the radius of the tusk. The iron absorbed from the duodenum binds to transferrin, and is carried by blood to different cells. These canals have different configurations in different ivories and their diameter ranges between 0.8 and 2.2 micrometres.

Iron distribution is heavily regulated in mammals, both as a defense against bacterial infection as well as the potential biological toxicity of iron. Dentine contains a microscopic structure called dentinal tubules which are micro-canals that radiate outward through the dentine from the pulp cavity to the exterior cementum border. When the body is fighting a bacterial infection, the body sequesters iron inside of cells (mostly stored in the storage molecule ferritin) so that it cannot be used by bacteria. The inorganic component of dentine consists of dahllite. A class of non-heme iron proteins is responsible for a wide range of functions within several life forms, such as enzymes methane monooxygenase (oxidizes methane to methanol), ribonucleotide reductase (reduces ribose to deoxyribose; DNA biosynthesis), hemerythrins (oxygen transport and fixation in marine invertebrates) and purple acid phosphatase (hydrolysis of phosphate esters). Dentine is a mineralized connective tissue with an organic matrix of collagenous proteins. Inorganic iron involved in redox reactions is also found in the iron-sulfur clusters of many enzymes, such as nitrogenase (involved in the synthesis of ammonia from nitrogen and hydrogen) and hydrogenase. Dentine, which is the main component of carved ivory objects, forms a layer of consistent thickness around the pulp cavity and comprises the bulk of the tooth and tusk.

Many animals incorporate iron into the heme complex, an essential component of cytochromes, which are proteins involved in redox reactions (including but not limited to cellular respiration), and of oxygen carrying proteins hemoglobin and myoglobin. Odontoblasts line the pulp cavity and are responsible for the production of dentine. Iron binds avidly to virtually all biomolecules so it will adhere nonspecifically to cell membranes, nucleic acids, proteins etc. The pulp cavity is an empty space within the tooth that conforms to the shape of the pulp. To say that iron is free doesn't mean that it is free floating in the bodily fluids. The innermost area is the pulp cavity. It is mostly stably incorporated in the inside of metalloproteins, because in exposed or in free form it causes production of free radicals that are generally toxic to cells. Teeth and tusks have the same physical structures: pulp cavity, dentine, cementum and enamel.

Iron is essential to all organisms, except for a few bacteria. The teeth of most mammals consists of a root and the tusk proper. For this reason, ⁵⁷Fe has application as a spin isotope in chemistry and biochemistry. Tusks, which are extremely large teeth projecting beyond the lips, have evolved from teeth and give certain species an evolutionary advantage. Of the stable isotopes, only ⁵⁷Fe has a nuclear spin (−1/2). Teeth are specialized structures adapted for food mastication. The abundance of ⁶⁰Ni present in extraterrestrial material may also provide further insight into the origin of the solar system and its early history. Teeth and tusks have the same origins.

Possibly the energy released by the decay of ⁶⁰Fe contributed, together with the energy released by decay of the radionuclide ²⁶Al, to the remelting and differentiation of asteroids after their formation 4.6 billion years ago. Therefore, "ivory" can correctly be used to describe any mammalian teeth or tusks of commercial interest which is large enough to be carved or scrimshawed. In phases of the meteorites Semarkona and Chervony Kut a correlation between the concentration of ⁶⁰Ni, the daughter product of ⁶⁰Fe, and the abundance of the stable iron isotopes could be found which is evidence for the existence of ⁶⁰Fe at time formation of solar system. The chemical structure of the teeth and tusks of mammals is the same regardless of the species of origin, and the trade in certain teeth and tusks other than elephant is well established and widespread. This is not true, as both ⁶²Ni and ⁵⁸Fe are more stable. . A common misconception is that this isotope represents the most stable nucleus possible, and that it thus would be impossible to perform fission or fusion on ⁵⁶Fe and still liberate energy. Plastics have been viewed by piano purists as an inferior ivory substitute on piano keys, although other recently developed materials more closely resemble the feel of real ivory.

The isotope ⁵⁶Fe is of particular interest to nuclear scientists. The word "ivory" was traditionally applied to the tusks of elephants. Much of the past work on measuring the isotopic composition of Fe has centered on determining ⁶⁰Fe variations due to processes accompanying nucleosynthesis (i.e., meteorite studies) and ore formation. Prior to the introduction of plastics, it was used for billiard balls, piano keys, buttons and ornamental items. ⁶⁰Fe is an extinct radionuclide of long half-life (1.5 million years). Ivory is a hard, white, opaque substance that is the bulk of the teeth and tusks of animals such as the elephant, hippopotamus, walrus, mammoth, etc. Naturally occurring iron consists of four isotopes: 5.845% of radioactive ⁵⁴Fe (half-life: >3.1E22 years), 91.754% of stable ⁵⁶Fe, 2.119% of stable ⁵⁷Fe and 0.282% of stable ⁵⁸Fe. Elk Ivory from the bugling teeth of bull elk.

Iron carbide Fe₃C is known as cementite. Warthog ivory. Note that despite the chemical formula, the iron in the common pyrite is not in the +4 oxidation state; the sulfur is in the -1 oxidation state. Hippopotamus ivory. Common oxidation states of iron include:. Narwhal ivory. The 1100Mt of iron ore was used to produce approximately 572Mt of pig iron. Sperm Whale and Killer Whale ivory.

While ore production occurs in 48 countries, the five largest producers were China, Brazil, Australia, Russia and India, accounting for 70% of world iron ore production. Walrus ivory from the tusks of a bull walrus. Approximately 1100Mt (million tons) of iron ore was produced in the world in 2000, with a gross market value of approximately 25 billion US dollars. Elephant and mammoth ivory from the tusks of bull elephants and mammoths. The iron, once cooled, is called pig iron, while the slag can be used as a material in road construction or to improve mineral-poor soils for agriculture. In the bottom of the furnace, the molten slag floats on top of the more dense liquid iron, and spouts in the side of the furnace may be opened to drain off either the iron or the slag.

The slag melts in the heat of the furnace, which silicon dioxide would not have. Then calcium oxide combines with silicon dioxide to form a slag. In the heat of the furnace the limestone flux decomposes to calcium oxide (quicklime):. Other fluxes may be used depending on the impurities that need to be removed from the ore.

Common fluxes include limestone (principally calcium carbonate) and dolomite (magnesium carbonate). The flux is present to melt impurities in the ore, principally silicon dioxide sand and other silicates. The carbon monoxide reduces the iron ore (in the chemical equation below, hematite) to molten iron, becoming carbon dioxide in the process:. In the furnace, the coke reacts with oxygen in the air blast to produce carbon monoxide:.

In a blast furnace, iron ore, carbon in the form of coke, and a flux such as limestone are fed into the top of the furnace, while a blast of heated air is forced into the furnace at the bottom. Industrially, iron is extracted from its ores, principally hematite (nominally Fe₂O₃) and magnetite (Fe₃O₄) by a carbothermic reaction (reduction with carbon) in a blast furnace at temperatures of about 2000°C. Iron is also one of the least reactive metals, and therefore, it is sometimes found pure in nature. Although rare, these are the major form of natural metallic iron on the earth's surface.

About 5% of the meteorites similarly consist of iron-nickel alloy. The earth's core is believed to consist largely of a metallic iron-nickel alloy. Most of this iron is found in various iron oxides, such as the minerals hematite, magnetite, and taconite. Iron is one of the most common elements on Earth, making up about 5% of the Earth's crust.

This innovation by Abraham Darby supplied the energy for the Industrial Revolution. In 18th century England, wood supplies ran down and coke, a fossil fuel, was used as an alternative. Early iron smelting (as the process is called) used charcoal as both the heat source and the reducing agent. In any event, by the late fourteenth century, a market for cast iron goods began to form, as a demand developed for cast iron cannonballs.

There are suggestions by scholars that the practice may have followed the Mongols across Russia to these sites, but there is no clear proof of this hypothesis. Some of the earliest casting of iron in Europe occurred in Sweden, in two sites, Lapphyttan and Vinarhyttan, between 1150 and 1350 AD. Through a good portion of the Middle Ages, in Western Europe, iron was still being made by the working of sponge iron into wrought iron. Cast iron development lagged in Europe, as the smelters could only achieve temperatures of about 1000 K.

Iron, however, remained a pedestrian product, used by farmers for hundreds of years, and did not really affect the nobility of China until the Qin dynasty (ca 221 BC). The vast majority of Chinese iron manufacture, from the Zhou dynasty onward, was of cast iron. This product is strong, can be cast into intricate shapes, but is too brittle to be worked, unless the product is decarburized to remove most of the carbon. If iron ores are heated with carbon to 1420–1470 K, a molten liquid is formed, an alloy of about 96.5% iron and 3.5% carbon.

The famous iron pillar in the Qutb complex in Delhi is made of very pure iron (98%) and has not rusted or eroded till this day. Iron was used in India as early as 250 BCE. Producing blast furnaces capable of temperatures exceeding 1300 K, the Chinese developed the manufacture of cast, or pig iron. In the later years of the Zhou Dynasty (ca 550 BC), a new iron manufacturing capability began because of a highly developed kiln technology.

These items were made of wrought iron, created by the same processes used in the Middle East and Europe, and were thought to be imported by non-Chinese people. In China the first irons used were also meteoric iron, with archeological evidence for items made of wrought iron appearing in the northwest, near Xinjiang, in the 8th century BC. The resulting product, which had a surface of steel, was harder and less brittle than the bronze it began to replace. The people of the Middle East found that a much harder product could be created by the long term heating of a wrought iron object in a bed of charcoal, which was then quenched in water or oil.

Wrought iron was very low in carbon content and was not easily hardened by quenching. Iron was recovered as sponge iron, a mix of iron and slag with some carbon and/or carbide, which was then repeatedly hammered and folded over to free the mass of slag and oxidise out carbon content, so creating the product wrought iron. Concurrent with the transition from bronze to iron was the discovery of carburization, which was the process of adding carbon to the irons of the time. A common alchemical symbol for iron, the metal of weapons, was that of Mars, the god of war.

This period of transition, which occurred at different times in different parts of the world, is the ushering in of an age of civilization called the Iron Age. The critical factor in this transition does not appear to be the sudden onset of a superior ironworking technology, but instead the disruption of the supply of tin. In the period from the 12th to 10th century BC, there was a rapid transition in the Middle East from bronze to iron tools and weapons. By 1600 BC to 1200 BC, iron was used increasingly in the Middle East, but did not supplant the dominant use of bronze.

Some resources (see the reference What Caused the Iron Age? below) suggest that iron was being created then as a by-product of copper refining, as sponge iron, and was not reproducible by the metallurgy of the time. In the Iliad, weaponry is mostly bronze, but iron ingots are used for trade. However, their use appears to be ceremonial, and iron was an expensive metal, more expensive than gold. By 3500 BC to 2000 BC, increasing numbers of smelted iron objects (distinguishable from meteoric iron by the lack of nickel in the product) appear in Mesopotamia, Anatolia, and Egypt.

Because meteorites fall from the sky some linguists have conjectured that the English word iron (OE īsern), which has cognates in many northern and western European languages, derives from the Etruscan aisar which means "the gods". The first signs of use of iron come from the Sumerians and the Egyptians, where around 4000 BC, a few items, such as the tips of spears, daggers and ornaments, were being fashioned from iron recovered from meteorites. Steel is the best known alloy of iron, and some of the forms that iron takes include:. Its combination of low cost and high strength make it indispensable, especially in applications like automobiles, the hulls of large ships, and structural components for buildings.

Iron is the most used of all the metals, comprising 95 percent of all the metal tonnage produced worldwide. Some cosmological models with an open universe predict that there will be a phase where as a result of slow fusion and fission reactions, everything will become iron. This leads to a supernova. When a very large star contracts at the end of its life, internal pressure and temperature rise, allowing the star to produce progressively heavier elements, despite these being less stable than the elements around mass number 60 (the "iron group").

Although a further tiny energy gain could be extracted by synthesizing ⁶²Ni, conditions in stars are not right for this process to be favoured. This is formed by nuclear fusion in the stars. The universally most abundant of the highly stable nucleides is, however, ⁵⁶Fe. Nuclei of iron have some of the highest binding energies per nucleon, superseded only by the nickel isotope ⁶²Ni.

Iron is used in the production of steel, which is not an element but an alloy, a solution of different metals (and some non-metals, particularly carbon). In order to obtain elemental iron, the impurities must be removed by chemical reduction. Iron is a metal extracted from iron ore, and is hardly ever found in the free (elemental) state. Iron is also the most abundant (by mass, 34.6%) element making up the Earth; the concentration of iron in the various layers of the Earth ranges from high at the inner core to about 5% in the outer crust; it is possible the Earth's inner core consists of a single iron crystal although it is more likely to be a mixture of iron and nickel; the large amount of iron in the Earth is thought to contribute to its magnetic field.

Iron is the most abundant metal on Earth, and is believed to be the tenth most abundant element in the universe. . It is therefore the most abundant heavy metal in the universe. Iron is notable for being the final element produced by stellar nucleosynthesis, and thus the heaviest element which does not require a supernova or similarly cataclysmic event for its formation.

Iron is a group 8 and period 4 metal. Iron is a chemical element with the symbol Fe (L.: Ferrum) and atomic number 26. Los Alamos National Laboratory — Iron. the Iron(VI) state, Fe⁶⁺ is also known, if rare, in potassium ferrate.

peroxidases). the Iron(IV) state, Fe⁴⁺, previously ferryl, stabilized in some enzymes (e.g. the Iron(III) state, Fe³⁺, previously ferric, is also very common, for example in rust. the Iron(II) state, Fe²⁺, previously ferrous is very common.

the Iron(I) state, [Fe(H₂O)₅NO]²⁺. the Iron(0) state, Fe(CO)₅, Fe(PF₃)₅. Fe(CO)₄^2-,Fe(CO)₂(NO)₂. the Iron(-II) state, Fe^2- (e.g.

They are often mixed with other compounds, and retain their magnetic properties in solution. Iron(III) oxides are used in the production of magnetic storage in computers. Recent developments in ferrous metallurgy have produced a growing range of microalloyed steels, also termed 'HSLA' or high-strength, low alloy steels, containing tiny additions to produce high strengths and often spectacular toughness at minimal cost. They are used for structural purposes, as their alloy content raises their cost and necessitates justification of their use.

Alloy steels contain varying amounts of carbon as well as other metals, such as chromium, vanadium, molybdenum, nickel, tungsten, etc. Wrought iron is characterised, especially in old samples, by the presence of fine 'stringers' or filaments of slag entrapped in the metal. If honed to an edge, it loses it quickly. It has a very small amount of carbon, a few tenths of a percent.

It is a tough, malleable product, not as fusible as pig iron. Wrought iron contains less than 0.2% carbon. Carbon steel contains between 0.4% and 1.5% carbon, with small amounts of manganese, sulfur, phosphorus, and silicon. A newer variant of grey iron, referred to as 'ductile iron' is specially treated with trace amounts of magnesium to alter the shape of graphite to sheroids, or nodules, vastly increasing the toughness and strength of the material.

In 'grey' cast iron, the carbon exists free as fine flakes of graphite , and also, renders the material brittle due to the stress-raising nature of the sharp edged flakes of graphite. The broken surface of a white cast iron is full of fine facets of the broken carbide, a very pale, silvery, shiny material, hence the appellation. This hard, brittle compound dominates the mechanical properties of white cast irons, rendering them hard, but unresistant to shock. 'White' cast irons contain their carbon in the form of cementite, or iron carbide.

Its mechanical properties vary greatly, dependant upon the form carbon takes in the alloy. It has a melting point in the range of 1420–1470 K, which is lower than either of its two main components, and makes it the first product to be melted when carbon and iron are heated together. Contaminants present in pig iron that negatively affect the material properties, such as sulfur and phosphorus, have been reduced to an acceptable level. Cast iron contains 2% – 4.0% carbon , 1% – 6% silicon , and small amounts of manganese.

Its only significance is that of an intermediate step on the way from iron ore to cast iron and steel. Pig iron has 4% – 5% carbon and contains varying amounts of contaminants such as sulfur, silicon and phosphorus.