110-732: Iron Age Scandinavia (or Nordic Iron Age ) was the Iron Age , as it unfolded in Scandinavia . It was preceded by the Nordic Bronze Age . The 6th and 5th centuries BC were a tipping point for exports and imports on the European continent. The ever-increasing conflicts and wars between the central European Celtic tribes and the Mediterranean cultures destabilized old major trade routes and networks between Scandinavia and
220-434: A body-centered cubic (bcc) crystal structure . As it cools further to 1394 °C, it changes to its γ-iron allotrope, a face-centered cubic (fcc) crystal structure, or austenite . At 912 °C and below, the crystal structure again becomes the bcc α-iron allotrope. The physical properties of iron at very high pressures and temperatures have also been studied extensively, because of their relevance to theories about
330-430: A nuclear spin (− 1 ⁄ 2 ). The nuclide Fe theoretically can undergo double electron capture to Cr, but the process has never been observed and only a lower limit on the half-life of 4.4×10 years has been established. Fe is an extinct radionuclide of long half-life (2.6 million years). It is not found on Earth, but its ultimate decay product is its granddaughter, the stable nuclide Ni . Much of
440-499: A supernova for their formation, involving rapid neutron capture by starting Fe nuclei. In the far future of the universe, assuming that proton decay does not occur, cold fusion occurring via quantum tunnelling would cause the light nuclei in ordinary matter to fuse into Fe nuclei. Fission and alpha-particle emission would then make heavy nuclei decay into iron, converting all stellar-mass objects to cold spheres of pure iron. Iron's abundance in rocky planets like Earth
550-526: A Celtiberian stronghold against Roman invasions. İt dates more than 2500 years back. The site was researched by Francisco Martins Sarmento starting from 1874. A number of amphoras (containers usually for wine or olive oil), coins, fragments of pottery, weapons, pieces of jewelry, as well as ruins of a bath and its pedra formosa ( lit. ' handsome stone ' ) revealed here. The Iron Age in Central Asia began when iron objects appear among
660-699: A combination of bivalve moulds of distinct southern tradition and the incorporation of piece mould technology from the Zhongyuan . The products of the combination of these two periods are bells, vessels, weapons and ornaments, and the sophisticated cast. An Iron Age culture of the Tibetan Plateau has been associated tentatively with the Zhang Zhung culture described by early Tibetan writings. In Japan, iron items, such as tools, weapons, and decorative objects, are postulated to have entered Japan during
770-951: A decline in standards of living. The Iron Age in Scandinavia and Northern Europe begins around 500 BC with the Jastorf culture , and is taken to last until c. 800 AD and the beginning Viking Age. It succeeds the Nordic Bronze Age with the introduction of ferrous metallurgy by contact with the Hallstatt D / La Tène cultures. The Northern European Iron Age is the locus of Proto-Germanic culture, in its later stage differentiating into Proto-Norse (in Scandinavia), and West Germanic ( Ingvaeonic , Irminonic , Istvaeonic ) in northern Germany. Iron Age The Iron Age ( c. 1200 – c. 550 BC )
880-454: A distorted sodium chloride structure. The binary ferrous and ferric halides are well-known. The ferrous halides typically arise from treating iron metal with the corresponding hydrohalic acid to give the corresponding hydrated salts. Iron reacts with fluorine, chlorine, and bromine to give the corresponding ferric halides, ferric chloride being the most common. Ferric iodide is an exception, being thermodynamically unstable due to
990-553: A macroscopic piece of iron will have a nearly zero overall magnetic field. Application of an external magnetic field causes the domains that are magnetized in the same general direction to grow at the expense of adjacent ones that point in other directions, reinforcing the external field. This effect is exploited in devices that need to channel magnetic fields to fulfill design function, such as electrical transformers , magnetic recording heads, and electric motors . Impurities, lattice defects , or grain and particle boundaries can "pin"
1100-475: A mixture of O 2 /Ar. Iron(IV) is a common intermediate in many biochemical oxidation reactions. Numerous organoiron compounds contain formal oxidation states of +1, 0, −1, or even −2. The oxidation states and other bonding properties are often assessed using the technique of Mössbauer spectroscopy . Many mixed valence compounds contain both iron(II) and iron(III) centers, such as magnetite and Prussian blue ( Fe 4 (Fe[CN] 6 ) 3 ). The latter
1210-471: A result, mercury is traded in standardized 76 pound flasks (34 kg) made of iron. Iron is by far the most reactive element in its group; it is pyrophoric when finely divided and dissolves easily in dilute acids, giving Fe . However, it does not react with concentrated nitric acid and other oxidizing acids due to the formation of an impervious oxide layer, which can nevertheless react with hydrochloric acid . High-purity iron, called electrolytic iron ,
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#17327663039441320-455: A type of rock consisting of repeated thin layers of iron oxides alternating with bands of iron-poor shale and chert . The banded iron formations were laid down in the time between 3,700 million years ago and 1,800 million years ago . Materials containing finely ground iron(III) oxides or oxide-hydroxides, such as ochre , have been used as yellow, red, and brown pigments since pre-historical times. They contribute as well to
1430-537: A universal "Bronze Age", and many areas transitioned directly from stone to iron. Some archaeologists believe that iron metallurgy was developed in sub-Saharan Africa independently from Eurasia and neighbouring parts of Northeast Africa as early as 2000 BC . The concept of the Iron Age ending with the beginning of the written historiographical record has not generalized well, as written language and steel use have developed at different times in different areas across
1540-435: A very large coordination and organometallic chemistry : indeed, it was the discovery of an iron compound, ferrocene , that revolutionalized the latter field in the 1950s. Iron is sometimes considered as a prototype for the entire block of transition metals, due to its abundance and the immense role it has played in the technological progress of humanity. Its 26 electrons are arranged in the configuration [Ar]3d 4s , of which
1650-705: A whole new economic development and trade. Bronze could not be produced in Scandinavia, as tin was not a local natural resource, but with new techniques, iron production from bog iron (mostly in Denmark) slowly gained ground. Iron is a versatile metal and was suitable for tools and weapons, but it was not until the Viking Age that iron incited a revolution in ploughing. Previously, herds of livestock had pasture grazed freely in large wood pastures , but were now placed in stables, probably to utilize manure more efficiently and increase agricultural production. Even though
1760-823: Is a chemical element ; it has the symbol Fe (from Latin ferrum 'iron') and atomic number 26. It is a metal that belongs to the first transition series and group 8 of the periodic table . It is, by mass, the most common element on Earth , forming much of Earth's outer and inner core . It is the fourth most abundant element in the Earth's crust , being mainly deposited by meteorites in its metallic state. Extracting usable metal from iron ores requires kilns or furnaces capable of reaching 1,500 °C (2,730 °F), about 500 °C (932 °F) higher than that required to smelt copper . Humans started to master that process in Eurasia during
1870-400: Is abundant naturally, temperatures above 1,250 °C (2,280 °F) are required to smelt it, impractical to achieve with the technology available commonly until the end of the second millennium BC. In contrast, the components of bronze—tin with a melting point of 231.9 °C (449.4 °F) and copper with a relatively moderate melting point of 1,085 °C (1,985 °F)—were within
1980-646: Is also rarely found in basalts that have formed from magmas that have come into contact with carbon-rich sedimentary rocks, which have reduced the oxygen fugacity sufficiently for iron to crystallize. This is known as telluric iron and is described from a few localities, such as Disko Island in West Greenland, Yakutia in Russia and Bühl in Germany. Ferropericlase (Mg,Fe)O , a solid solution of periclase (MgO) and wüstite (FeO), makes up about 20% of
2090-669: Is also speculated that Early Iron Age sites may exist in Kandarodai , Matota, Pilapitiya and Tissamaharama . The earliest undisputed deciphered epigraphy found in the Indian subcontinent are the Edicts of Ashoka of the 3rd century BC, in the Brahmi script . Several inscriptions were thought to be pre-Ashokan by earlier scholars; these include the Piprahwa relic casket inscription,
2200-407: Is considered to be resistant to rust, due to its oxide layer. Iron forms various oxide and hydroxide compounds ; the most common are iron(II,III) oxide (Fe 3 O 4 ), and iron(III) oxide (Fe 2 O 3 ). Iron(II) oxide also exists, though it is unstable at room temperature. Despite their names, they are actually all non-stoichiometric compounds whose compositions may vary. These oxides are
2310-536: Is considered to last from c. 1200 BC (the Bronze Age collapse ) to c. 550 BC (or 539 BC ), roughly the beginning of historiography with Herodotus , marking the end of the proto-historical period. In China , because writing was developed first, there is no recognizable prehistoric period characterized by ironworking, and the Bronze Age China transitions almost directly into
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#17327663039442420-487: Is divided into two periods based on the Hallstatt culture (early Iron Age) and La Tène (late Iron Age) cultures. Material cultures of Hallstatt and La Tène consist of 4 phases (A, B, C, D). The Iron Age in Europe is characterized by an elaboration of designs of weapons, implements, and utensils. These are no longer cast but hammered into shape, and decoration is elaborate and curvilinear rather than simple rectilinear;
2530-499: Is due to its abundant production during the runaway fusion and explosion of type Ia supernovae , which scatters the iron into space. Metallic or native iron is rarely found on the surface of the Earth because it tends to oxidize. However, both the Earth's inner and outer core , which together account for 35% of the mass of the whole Earth, are believed to consist largely of an iron alloy, possibly with nickel . Electric currents in
2640-474: Is experimentally well defined for pressures less than 50 GPa. For greater pressures, published data (as of 2007) still varies by tens of gigapascals and over a thousand kelvin. Below its Curie point of 770 °C (1,420 °F; 1,040 K), α-iron changes from paramagnetic to ferromagnetic : the spins of the two unpaired electrons in each atom generally align with the spins of its neighbors, creating an overall magnetic field . This happens because
2750-873: Is from Malhar and its surrounding area. This site is assumed as the center for smelted bloomer iron to this area due to its location in the Karamnasa River and Ganga River. This site shows agricultural technology as iron implements sickles, nails, clamps, spearheads, etc., by at least c. 1500 BC. Archaeological excavations in Hyderabad show an Iron Age burial site. The beginning of the 1st millennium BC saw extensive developments in iron metallurgy in India. Technological advancement and mastery of iron metallurgy were achieved during this period of peaceful settlements. One ironworking centre in East India has been dated to
2860-443: Is in Earth's crust only amounts to about 5% of the overall mass of the crust and is thus only the fourth most abundant element in that layer (after oxygen , silicon , and aluminium ). Most of the iron in the crust is combined with various other elements to form many iron minerals . An important class is the iron oxide minerals such as hematite (Fe 2 O 3 ), magnetite (Fe 3 O 4 ), and siderite (FeCO 3 ), which are
2970-556: Is likely that the use of ironware made of steel had already begun in the third millennium BC in Central Anatolia". Souckova-Siegolová (2001) shows that iron implements were made in Central Anatolia in very limited quantities about 1800 BC and were in general use by elites, though not by commoners, during the New Hittite Empire (≈1400–1200 BC). Similarly, recent archaeological remains of iron-working in
3080-401: Is not like that of Mn with its weak, spin-forbidden d–d bands, because Fe has higher positive charge and is more polarizing, lowering the energy of its ligand-to-metal charge transfer absorptions. Thus, all the above complexes are rather strongly colored, with the single exception of the hexaquo ion – and even that has a spectrum dominated by charge transfer in the near ultraviolet region. On
3190-407: Is possible, but nonetheless the sequence does effectively end at Ni because conditions in stellar interiors cause the competition between photodisintegration and the alpha process to favor photodisintegration around Ni. This Ni, which has a half-life of about 6 days, is created in quantity in these stars, but soon decays by two successive positron emissions within supernova decay products in
3300-626: Is recorded to extend 10 ha (25 acres) by 800 BC and grew to 50 ha (120 acres) by 700–600 BC to become a town. The skeletal remains of an Early Iron Age chief were excavated in Anaikoddai, Jaffna . The name "Ko Veta" is engraved in Brahmi script on a seal buried with the skeleton and is assigned by the excavators to the 3rd century BC. Ko, meaning "King" in Tamil, is comparable to such names as Ko Atan and Ko Putivira occurring in contemporary Brahmi inscriptions in south India. It
3410-515: Is singularly scarce in collections of Egyptian antiquities. Bronze remained the primary material there until the conquest by the Neo-Assyrian Empire in 671 BC. The explanation of this would seem to be that the relics are in most cases the paraphernalia of tombs, the funeral vessels and vases, and iron being considered an impure metal by the ancient Egyptians it was never used in their manufacture of these or for any religious purposes. It
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3520-548: Is somewhat different). Pieces of magnetite with natural permanent magnetization ( lodestones ) provided the earliest compasses for navigation. Particles of magnetite were extensively used in magnetic recording media such as core memories , magnetic tapes , floppies , and disks , until they were replaced by cobalt -based materials. Iron has four stable isotopes : Fe (5.845% of natural iron), Fe (91.754%), Fe (2.119%) and Fe (0.282%). Twenty-four artificial isotopes have also been created. Of these stable isotopes, only Fe has
3630-442: Is such a strong oxidizing agent that it oxidizes ammonia to nitrogen (N 2 ) and water to oxygen: The pale-violet hex aquo complex [Fe(H 2 O) 6 ] is an acid such that above pH 0 it is fully hydrolyzed: As pH rises above 0 the above yellow hydrolyzed species form and as it rises above 2–3, reddish-brown hydrous iron(III) oxide precipitates out of solution. Although Fe has a d configuration, its absorption spectrum
3740-502: Is supposed to have an orthorhombic or a double hcp structure. (Confusingly, the term "β-iron" is sometimes also used to refer to α-iron above its Curie point, when it changes from being ferromagnetic to paramagnetic, even though its crystal structure has not changed. ) The inner core of the Earth is generally presumed to consist of an iron- nickel alloy with ε (or β) structure. The melting and boiling points of iron, along with its enthalpy of atomization , are lower than those of
3850-653: Is the final epoch of the three historical Metal Ages , after the Chalcolithic and Bronze Age . It has also been considered as the final age of the three-age division starting with prehistory (before recorded history) and progressing to protohistory (before written history). In this usage, it is preceded by the Stone Age (subdivided into the Paleolithic , Mesolithic and Neolithic ) and Bronze Age. These concepts originated for describing Iron Age Europe and
3960-411: Is the mass production of tools and weapons made not just of found iron, but from smelted steel alloys with an added carbon content. Only with the capability of the production of carbon steel does ferrous metallurgy result in tools or weapons that are harder and lighter than bronze . Smelted iron appears sporadically in the archeological record from the middle Bronze Age . Whilst terrestrial iron
4070-418: Is thus very important economically, and iron is the cheapest metal, with a price of a few dollars per kilogram or pound. Pristine and smooth pure iron surfaces are a mirror-like silvery-gray. Iron reacts readily with oxygen and water to produce brown-to-black hydrated iron oxides , commonly known as rust . Unlike the oxides of some other metals that form passivating layers, rust occupies more volume than
4180-451: Is used as the traditional "blue" in blueprints . Iron is the first of the transition metals that cannot reach its group oxidation state of +8, although its heavier congeners ruthenium and osmium can, with ruthenium having more difficulty than osmium. Ruthenium exhibits an aqueous cationic chemistry in its low oxidation states similar to that of iron, but osmium does not, favoring high oxidation states in which it forms anionic complexes. In
4290-437: Is used in chemical actinometry and along with its sodium salt undergoes photoreduction applied in old-style photographic processes. The dihydrate of iron(II) oxalate has a polymeric structure with co-planar oxalate ions bridging between iron centres with the water of crystallisation located forming the caps of each octahedron, as illustrated below. Iron(III) complexes are quite similar to those of chromium (III) with
4400-455: The 2nd millennium BC and the use of iron tools and weapons began to displace copper alloys – in some regions, only around 1200 BC. That event is considered the transition from the Bronze Age to the Iron Age . In the modern world , iron alloys, such as steel , stainless steel , cast iron and special steels , are by far the most common industrial metals, due to their mechanical properties and low cost. The iron and steel industry
4510-554: The Ancient Near East . The indigenous cultures of the New World did not develop an iron economy before 1500 . Although meteoric iron has been used for millennia in many regions, the beginning of the Iron Age is defined locally around the world by archaeological convention when the production of smelted iron (especially steel tools and weapons) replaces their bronze equivalents in common use. In Anatolia and
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4620-931: The Badli pillar inscription , the Bhattiprolu relic casket inscription, the Sohgaura copper plate inscription , the Mahasthangarh Brahmi inscription, the Eran coin legend, the Taxila coin legends, and the inscription on the silver coins of Sophytes . However, more recent scholars have dated them to later periods. Dates are approximate; consult particular article for details. Archaeology in Thailand at sites Ban Don Ta Phet and Khao Sam Kaeo yielding metallic, stone, and glass artifacts stylistically associated with
4730-661: The Caucasus , or Southeast Europe , the Iron Age began during the late 2nd millennium BC ( c. 1300 BC). In the Ancient Near East , this transition occurred simultaneously with the Late Bronze Age collapse , during the 12th century BC (1200–1100 BC). The technology soon spread throughout the Mediterranean Basin region and to South Asia between the 12th and 11th century BC. Its further spread to Central Asia , Eastern Europe , and Central Europe
4840-687: The Ganges Valley in India have been dated tentatively to 1800 BC. Tewari (2003) concludes that "knowledge of iron smelting and manufacturing of iron artifacts was well known in the Eastern Vindhyas and iron had been in use in the Central Ganga Plain, at least from the early second millennium BC". By the Middle Bronze Age increasing numbers of smelted iron objects (distinguishable from meteoric iron by
4950-540: The Geum River basin . The time that iron production begins is the same time that complex chiefdoms of Proto-historic Korea emerged. The complex chiefdoms were the precursors of early states such as Silla , Baekje , Goguryeo , and Gaya Iron ingots were an important mortuary item and indicated the wealth or prestige of the deceased during this period. Dates are approximate; consult particular article for details. The earliest evidence of iron smelting predates
5060-727: The Indo-European Saka in present-day Xinjiang (China) between the 10th century BC and the 7th century BC, such as those found at the cemetery site of Chawuhukou. The Pazyryk culture is an Iron Age archaeological culture ( c. 6th to 3rd centuries BC) identified by excavated artifacts and mummified humans found in the Siberian permafrost in the Altay Mountains . Dates are approximate; consult particular article for details. In China, Chinese bronze inscriptions are found around 1200 BC, preceding
5170-462: The Nordic Bronze Age . The rising power, wealth and organization of the central European tribes in the following centuries did not seem to instigate an increased trade and contact between Scandinavia and central Europe before 200‒100 BC. At this point the Celtic tribes had organized themselves in numerous urban communities known as oppida , and the more stable political situation in Europe allowed for
5280-730: The Orchid Island . Early evidence for iron technology in Sub-Saharan Africa can be found at sites such as KM2 and KM3 in northwest Tanzania and parts of Nigeria and the Central African Republic. Nubia was one of the relatively few places in Africa to have a sustained Bronze Age along with Egypt and much of the rest of North Africa . Archaeometallurgical scientific knowledge and technological development originated in numerous centers of Africa;
5390-511: The Qin dynasty of imperial China. "Iron Age" in the context of China is used sometimes for the transitional period of c. 900 BC to 100 BC during which ferrous metallurgy was present even if not dominant. The Iron Age in the Ancient Near East is believed to have begun after the discovery of iron smelting and smithing techniques in Anatolia , the Caucasus or Southeast Europe during
5500-589: The Yangtse Valley toward the end of the 6th century BC. The few objects were found at Changsha and Nanjing . The mortuary evidence suggests that the initial use of iron in Lingnan belongs to the mid-to-late Warring States period (from about 350 BC). Important non-precious husi style metal finds include iron tools found at the tomb at Guwei-cun of the 4th century BC. The techniques used in Lingnan are
5610-432: The supernova remnant gas cloud, first to radioactive Co, and then to stable Fe. As such, iron is the most abundant element in the core of red giants , and is the most abundant metal in iron meteorites and in the dense metal cores of planets such as Earth . It is also very common in the universe, relative to other stable metals of approximately the same atomic weight . Iron is the sixth most abundant element in
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#17327663039445720-491: The trans - chlorohydridobis(bis-1,2-(diphenylphosphino)ethane)iron(II) complex is used as a starting material for compounds with the Fe( dppe ) 2 moiety . The ferrioxalate ion with three oxalate ligands displays helical chirality with its two non-superposable geometries labelled Λ (lambda) for the left-handed screw axis and Δ (delta) for the right-handed screw axis, in line with IUPAC conventions. Potassium ferrioxalate
5830-466: The universe , and the most common refractory element. Although a further tiny energy gain could be extracted by synthesizing Ni , which has a marginally higher binding energy than Fe, conditions in stars are unsuitable for this process. Element production in supernovas greatly favor iron over nickel, and in any case, Fe still has a lower mass per nucleon than Ni due to its higher fraction of lighter protons. Hence, elements heavier than iron require
5940-570: The 3d and 4s electrons are relatively close in energy, and thus a number of electrons can be ionized. Iron forms compounds mainly in the oxidation states +2 ( iron(II) , "ferrous") and +3 ( iron(III) , "ferric"). Iron also occurs in higher oxidation states , e.g., the purple potassium ferrate (K 2 FeO 4 ), which contains iron in its +6 oxidation state. The anion [FeO 4 ] with iron in its +7 oxidation state, along with an iron(V)-peroxo isomer, has been detected by infrared spectroscopy at 4 K after cocondensation of laser-ablated Fe atoms with
6050-515: The Bronze Age. In Central and Western Europe, the Roman conquests of the 1st century BC serve as marking the end of the Iron Age. The Germanic Iron Age of Scandinavia is considered to end c. AD 800 , with the beginning of the Viking Age . The three-age method of Stone, Bronze, and Iron Ages was first used for the archaeology of Europe during the first half of the 19th century, and by
6160-603: The Earth's surface. Items made of cold-worked meteoritic iron have been found in various archaeological sites dating from a time when iron smelting had not yet been developed; and the Inuit in Greenland have been reported to use iron from the Cape York meteorite for tools and hunting weapons. About 1 in 20 meteorites consist of the unique iron-nickel minerals taenite (35–80% iron) and kamacite (90–95% iron). Native iron
6270-459: The Indian subcontinent began prior to the 3rd millennium BC. Archaeological sites in India, such as Malhar, Dadupur, Raja Nala Ka Tila, Lahuradewa, Kosambi and Jhusi , Allahabad in present-day Uttar Pradesh show iron implements in the period 1800–1200 BC. As the evidence from the sites Raja Nala ka tila, Malhar suggest the use of Iron in c. 1800/1700 BC. The extensive use of iron smelting
6380-770: The Indian subcontinent suggest Indianization of Southeast Asia beginning in the 4th to 2nd centuries BC during the late Iron Age. In Philippines and Vietnam , the Sa Huynh culture showed evidence of an extensive trade network. Sa Huynh beads were made from glass, carnelian, agate, olivine, zircon, gold and garnet; most of these materials were not local to the region and were most likely imported. Han-dynasty-style bronze mirrors were also found in Sa Huynh sites. Conversely, Sa Huynh produced ear ornaments have been found in archaeological sites in Central Thailand, as well as
6490-632: The Late Bronze Age continued into the Early Iron Age. Thus, there is a sociocultural continuity during this transitional period. In Iran, the earliest actual iron artifacts were unknown until the 9th century BC. For Iran, the best studied archaeological site during this time period is Teppe Hasanlu . In the Mesopotamian states of Sumer , Akkad and Assyria , the initial use of iron reaches far back, to perhaps 3000 BC. One of
6600-589: The Late Bronze Age. As part of the Late Bronze Age-Early Iron Age, the Bronze Age collapse saw the slow, comparatively continuous spread of iron-working technology in the region. It was long believed that the success of the Hittite Empire during the Late Bronze Age had been based on the advantages entailed by the "monopoly" on ironworking at the time. Accordingly, the invading Sea Peoples would have been responsible for spreading
6710-462: The Mediterranean, eventually breaking them down. Archaeology attests a rapid and deep change in the Scandinavian culture and way of life due to various reasons which have not yet been sufficiently analyzed. Agricultural production became more intensified, organized around larger settlements and with a much more labour-intensive production. Slaves were introduced and deployed, something uncommon in
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#17327663039446820-607: The Romans, though ironworking remained the dominant technology until recent times. Elsewhere it may last until the early centuries AD, and either Christianization or a new conquest during the Migration Period . Iron working was introduced to Europe during the late 11th century BC, probably from the Caucasus , and slowly spread northwards and westwards over the succeeding 500 years. The Iron Age did not start when iron first appeared in Europe but it began to replace bronze in
6930-420: The advent of the Iron Age in Scandinavia was a time of great crisis, the new agricultural expansions, techniques and organizations proceeded apace. And though the decline of foreign trade might suggest that the period marked a transition from a rich and wealthy culture to a poor and meagre one, the population grew and new technology was developed. The period might just reflect a change of culture and not necessarily
7040-654: The archaeological record. For instance, in China, written history started before iron smelting began, so the term is used infrequently for the archaeology of China. For the Ancient Near East, the establishment of the Achaemenid Empire c. 550 BC is used traditionally and still usually as an end date; later dates are considered historical according to the record by Herodotus despite considerable written records now being known from well back into
7150-608: The beginning of the Western Han dynasty . Yoon proposes that iron was first introduced to chiefdoms located along North Korean river valleys that flow into the Yellow Sea such as the Cheongcheon and Taedong Rivers. Iron production quickly followed during the 2nd century BC, and iron implements came to be used by farmers by the 1st century in southern Korea. The earliest known cast-iron axes in southern Korea are found in
7260-450: The brown deposits present in a sizeable number of streams. Due to its electronic structure, iron has a very large coordination and organometallic chemistry. Many coordination compounds of iron are known. A typical six-coordinate anion is hexachloroferrate(III), [FeCl 6 ] , found in the mixed salt tetrakis(methylammonium) hexachloroferrate(III) chloride . Complexes with multiple bidentate ligands have geometric isomers . For example,
7370-482: The capabilities of Neolithic kilns , which date back to 6000 BC and were able to produce temperatures greater than 900 °C (1,650 °F). In addition to specially designed furnaces, ancient iron production required the development of complex procedures for the removal of impurities, the regulation of the admixture of carbon, and the invention of hot-working to achieve a useful balance of hardness and strength in steel. The use of steel has also been regulated by
7480-767: The centers of origin were located in West Africa , Central Africa , and East Africa ; consequently, as these origin centers are located within inner Africa, these archaeometallurgical developments are thus native African technologies. Iron metallurgical development occurred 2631–2458 BC at Lejja, in Nigeria, 2136–1921 BC at Obui, in Central Africa Republic, 1895–1370 BC at Tchire Ouma 147, in Niger, and 1297–1051 BC at Dekpassanware, in Togo. Iron Iron
7590-430: The color of various rocks and clays , including entire geological formations like the Painted Hills in Oregon and the Buntsandstein ("colored sandstone", British Bunter ). Through Eisensandstein (a jurassic 'iron sandstone', e.g. from Donzdorf in Germany) and Bath stone in the UK, iron compounds are responsible for the yellowish color of many historical buildings and sculptures. The proverbial red color of
7700-464: The cores of the Earth and other planets. Above approximately 10 GPa and temperatures of a few hundred kelvin or less, α-iron changes into another hexagonal close-packed (hcp) structure, which is also known as ε-iron . The higher-temperature γ-phase also changes into ε-iron, but does so at higher pressure. Some controversial experimental evidence exists for a stable β phase at pressures above 50 GPa and temperatures of at least 1500 K. It
7810-417: The development of iron metallurgy, which was known by the 9th century BC. The large seal script is identified with a group of characters from a book entitled Shǐ Zhòu Piān ( c. 800 BC). Therefore, in China prehistory had given way to history periodized by ruling dynasties by the start of iron use, so "Iron Age" is not used typically to describe a period of Chinese history. Iron metallurgy reached
7920-401: The domains in the new positions, so that the effect persists even after the external field is removed – thus turning the iron object into a (permanent) magnet . Similar behavior is exhibited by some iron compounds, such as the ferrites including the mineral magnetite , a crystalline form of the mixed iron(II,III) oxide Fe 3 O 4 (although the atomic-scale mechanism, ferrimagnetism ,
8030-479: The earlier 3d elements from scandium to chromium , showing the lessened contribution of the 3d electrons to metallic bonding as they are attracted more and more into the inert core by the nucleus; however, they are higher than the values for the previous element manganese because that element has a half-filled 3d sub-shell and consequently its d-electrons are not easily delocalized. This same trend appears for ruthenium but not osmium . The melting point of iron
8140-531: The earliest smelted iron artifacts known is a dagger with an iron blade found in a Hattic tomb in Anatolia , dating from 2500 BC. The widespread use of iron weapons which replaced bronze weapons rapidly disseminated throughout the Near East (North Africa, southwest Asia ) by the beginning of the 1st millennium BC. The development of iron smelting was once attributed to the Hittites of Anatolia during
8250-497: The economics of the metallurgical advancements. The earliest tentative evidence for iron-making is a small number of iron fragments with the appropriate amounts of carbon admixture found in the Proto-Hittite layers at Kaman-Kalehöyük in modern-day Turkey, dated to 2200–2000 BC. Akanuma (2008) concludes that "The combination of carbon dating, archaeological context, and archaeometallurgical examination indicates that it
8360-560: The emergence of the Iron Age proper by several centuries. Iron was being used in Mundigak to manufacture some items in the 3rd millennium BC such as a small copper/bronze bell with an iron clapper, a copper/bronze rod with two iron decorative buttons, and a copper/bronze mirror handle with a decorative iron button. Artefacts including small knives and blades have been discovered in the Indian state of Telangana which have been dated between 2400 BC and 1800 BC. The history of metallurgy in
8470-520: The end of the Bronze Age . The Iron Age in Europe is often considered as a part of the Bronze Age collapse in the ancient Near East . Anthony Snodgrass suggests that a shortage of tin and trade disruptions in the Mediterranean about 1300 BC forced metalworkers to seek an alternative to bronze. Many bronze implements were recycled into weapons during that time, and more widespread use of iron resulted in improved steel-making technology and lower costs. When tin became readily available again, iron
8580-498: The excavation of Ugarit. A dagger with an iron blade found in Tutankhamun's tomb , 13th century BC, was examined recently and found to be of meteoric origin. In Europe, the Iron Age is the last stage of prehistoric Europe and the first of the protohistoric periods, which initially means descriptions of a particular area by Greek and Roman writers. For much of Europe, the period came to an abrupt local end after conquest by
8690-406: The exception of iron(III)'s preference for O -donor instead of N -donor ligands. The latter tend to be rather more unstable than iron(II) complexes and often dissociate in water. Many Fe–O complexes show intense colors and are used as tests for phenols or enols . For example, in the ferric chloride test , used to determine the presence of phenols, iron(III) chloride reacts with a phenol to form
8800-465: The first millennium BC. In Southern India (present-day Mysore ) iron appeared as early as 12th to 11th centuries BC; these developments were too early for any significant close contact with the northwest of the country. The Indian Upanishads mention metallurgy. and the Indian Mauryan period saw advances in metallurgy. As early as 300 BC, certainly by 200 AD, high-quality steel
8910-480: The forms and character of the ornamentation of the northern European weapons resemble in some respects Roman arms, while in other respects they are peculiar and evidently representative of northern art. Citânia de Briteiros , located in Guimarães , Portugal, is one of the examples of archaeological sites of the Iron Age. This settlement (fortified villages) covered an area of 3.8 hectares (9.4 acres), and served as
9020-462: The global stock of iron in use in society is 2,200 kg per capita. More-developed countries differ in this respect from less-developed countries (7,000–14,000 vs 2,000 kg per capita). Ocean science demonstrated the role of the iron in the ancient seas in both marine biota and climate. Iron shows the characteristic chemical properties of the transition metals , namely the ability to form variable oxidation states differing by steps of one and
9130-498: The knowledge through that region. The idea of such a "Hittite monopoly" has been examined more thoroughly and no longer represents a scholarly consensus. While there are some iron objects from Bronze Age Anatolia, the number is comparable to iron objects found in Egypt and other places of the same time period; and only a small number of these objects are weapons. Dates are approximate; consult particular article for details. Iron metal
9240-567: The lack of nickel in the product) appeared in the Middle East , Southeast Asia and South Asia . African sites are revealing dates as early as 2000–1200 BC. However, some recent studies date the inception of iron metallurgy in Africa between 3000 and 2500 BC, with evidence existing for early iron metallurgy in parts of Nigeria, Cameroon, and Central Africa, from as early as around 2,000 BC. The Nok culture of Nigeria may have practiced iron smelting from as early as 1000 BC, while
9350-528: The late 2nd millennium BC ( c. 1300 BC). The earliest bloomery smelting of iron is found at Tell Hammeh , Jordan about 930 BC (determined from C dating ). The Early Iron Age in the Caucasus area is divided conventionally into two periods, Early Iron I, dated to about 1100 BC, and the Early Iron II phase from the tenth to ninth centuries BC. Many of the material culture traditions of
9460-550: The late Yayoi period ( c. 300 BC – 300 AD) or the succeeding Kofun period ( c. 250–538 AD), most likely from the Korean Peninsula and China. Distinguishing characteristics of the Yayoi period include the appearance of new pottery styles and the start of intensive rice agriculture in paddy fields. Yayoi culture flourished in a geographic area from southern Kyūshū to northern Honshū . The Kofun and
9570-507: The latter half of the 19th century, it had been extended to the archaeology of the Ancient Near East. Its name harks back to the mythological " Ages of Man " of Hesiod . As an archaeological era, it was first introduced to Scandinavia by Christian Jürgensen Thomsen during the 1830s. By the 1860s, it was embraced as a useful division of the "earliest history of mankind" in general and began to be applied in Assyriology . The development of
9680-453: The liquid outer core are believed to be the origin of the Earth's magnetic field . The other terrestrial planets ( Mercury , Venus , and Mars ) as well as the Moon are believed to have a metallic core consisting mostly of iron. The M-type asteroids are also believed to be partly or mostly made of metallic iron alloy. The rare iron meteorites are the main form of natural metallic iron on
9790-446: The literature, this mineral phase of the lower mantle is also often called magnesiowüstite. Silicate perovskite may form up to 93% of the lower mantle, and the magnesium iron form, (Mg,Fe)SiO 3 , is considered to be the most abundant mineral in the Earth, making up 38% of its volume. While iron is the most abundant element on Earth, most of this iron is concentrated in the inner and outer cores. The fraction of iron that
9900-407: The major ores of iron . Many igneous rocks also contain the sulfide minerals pyrrhotite and pentlandite . During weathering , iron tends to leach from sulfide deposits as the sulfate and from silicate deposits as the bicarbonate. Both of these are oxidized in aqueous solution and precipitate in even mildly elevated pH as iron(III) oxide . Large deposits of iron are banded iron formations ,
10010-775: The metal and thus flakes off, exposing more fresh surfaces for corrosion. Chemically, the most common oxidation states of iron are iron(II) and iron(III) . Iron shares many properties of other transition metals, including the other group 8 elements , ruthenium and osmium . Iron forms compounds in a wide range of oxidation states , −4 to +7. Iron also forms many coordination compounds ; some of them, such as ferrocene , ferrioxalate , and Prussian blue have substantial industrial, medical, or research applications. The body of an adult human contains about 4 grams (0.005% body weight) of iron, mostly in hemoglobin and myoglobin . These two proteins play essential roles in oxygen transport by blood and oxygen storage in muscles . To maintain
10120-612: The meteorites Semarkona and Chervony Kut, a correlation between the concentration of Ni, the granddaughter of Fe, and the abundance of the stable iron isotopes provided evidence for the existence of Fe at the time of formation of the Solar System . Possibly the energy released by the decay of Fe, along with that released by Al , contributed to the remelting and differentiation of asteroids after their formation 4.6 billion years ago. The abundance of Ni present in extraterrestrial material may bring further insight into
10230-531: The nearby Djenné-Djenno culture of the Niger Valley in Mali shows evidence of iron production from c. 250 BC. Iron technology across much of sub-Saharan Africa has an African origin dating to before 2000 BC. These findings confirm the independent invention of iron smelting in sub-Saharan Africa. Modern archaeological evidence identifies the start of large-scale global iron production about 1200 BC, marking
10340-559: The necessary levels, human iron metabolism requires a minimum of iron in the diet. Iron is also the metal at the active site of many important redox enzymes dealing with cellular respiration and oxidation and reduction in plants and animals. At least four allotropes of iron (differing atom arrangements in the solid) are known, conventionally denoted α , γ , δ , and ε . The first three forms are observed at ordinary pressures. As molten iron cools past its freezing point of 1538 °C, it crystallizes into its δ allotrope, which has
10450-540: The now-conventional periodization in the archaeology of the Ancient Near East was developed during the 1920s and 1930s. Meteoric iron, a natural iron–nickel alloy , was used by various ancient peoples thousands of years before the Iron Age. The earliest-known meteoric iron artifacts are nine small beads dated to 3200 BC , which were found in burials at Gerzeh in Lower Egypt , having been shaped by careful hammering. The characteristic of an Iron Age culture
10560-436: The orbitals of those two electrons (d z and d x − y ) do not point toward neighboring atoms in the lattice, and therefore are not involved in metallic bonding. In the absence of an external source of magnetic field, the atoms get spontaneously partitioned into magnetic domains , about 10 micrometers across, such that the atoms in each domain have parallel spins, but some domains have other orientations. Thus
10670-539: The origin and early history of the Solar System . The most abundant iron isotope Fe is of particular interest to nuclear scientists because it represents the most common endpoint of nucleosynthesis . Since Ni (14 alpha particles ) is easily produced from lighter nuclei in the alpha process in nuclear reactions in supernovae (see silicon burning process ), it is the endpoint of fusion chains inside extremely massive stars . Although adding more alpha particles
10780-444: The other hand, the pale green iron(II) hexaquo ion [Fe(H 2 O) 6 ] does not undergo appreciable hydrolysis. Carbon dioxide is not evolved when carbonate anions are added, which instead results in white iron(II) carbonate being precipitated out. In excess carbon dioxide this forms the slightly soluble bicarbonate, which occurs commonly in groundwater, but it oxidises quickly in air to form iron(III) oxide that accounts for
10890-581: The oxidizing power of Fe and the high reducing power of I : Ferric iodide, a black solid, is not stable in ordinary conditions, but can be prepared through the reaction of iron pentacarbonyl with iodine and carbon monoxide in the presence of hexane and light at the temperature of −20 °C, with oxygen and water excluded. Complexes of ferric iodide with some soft bases are known to be stable compounds. The standard reduction potentials in acidic aqueous solution for some common iron ions are given below: The red-purple tetrahedral ferrate (VI) anion
11000-497: The past work on isotopic composition of iron has focused on the nucleosynthesis of Fe through studies of meteorites and ore formation. In the last decade, advances in mass spectrometry have allowed the detection and quantification of minute, naturally occurring variations in the ratios of the stable isotopes of iron. Much of this work is driven by the Earth and planetary science communities, although applications to biological and industrial systems are emerging. In phases of
11110-580: The preparation of tools and weapons. It did not happen at the same time throughout Europe; local cultural developments played a role in the transition to the Iron Age. For example, the Iron Age of Prehistoric Ireland begins about 500 BC (when the Greek Iron Age had already ended) and finishes about 400 AD. The widespread use of the technology of iron was implemented in Europe simultaneously with Asia. The prehistoric Iron Age in Central Europe
11220-414: The principal ores for the production of iron (see bloomery and blast furnace). They are also used in the production of ferrites , useful magnetic storage media in computers, and pigments. The best known sulfide is iron pyrite (FeS 2 ), also known as fool's gold owing to its golden luster. It is not an iron(IV) compound, but is actually an iron(II) polysulfide containing Fe and S 2 ions in
11330-437: The second half of the 3d transition series, vertical similarities down the groups compete with the horizontal similarities of iron with its neighbors cobalt and nickel in the periodic table, which are also ferromagnetic at room temperature and share similar chemistry. As such, iron, cobalt, and nickel are sometimes grouped together as the iron triad . Unlike many other metals, iron does not form amalgams with mercury . As
11440-637: The subsequent Asuka periods are sometimes referred to collectively as the Yamato period ; The word kofun is Japanese for the type of burial mounds dating from that era. Iron objects were introduced to the Korean peninsula through trade with chiefdoms and state-level societies in the Yellow Sea area during the 4th century BC, just at the end of the Warring States Period but prior to
11550-564: The surface of Mars is derived from an iron oxide-rich regolith . Significant amounts of iron occur in the iron sulfide mineral pyrite (FeS 2 ), but it is difficult to extract iron from it and it is therefore not exploited. In fact, iron is so common that production generally focuses only on ores with very high quantities of it. According to the International Resource Panel 's Metal Stocks in Society report ,
11660-455: The volume of the lower mantle of the Earth, which makes it the second most abundant mineral phase in that region after silicate perovskite (Mg,Fe)SiO 3 ; it also is the major host for iron in the lower mantle. At the bottom of the transition zone of the mantle, the reaction γ- (Mg,Fe) 2 [SiO 4 ] ↔ (Mg,Fe)[SiO 3 ] + (Mg,Fe)O transforms γ-olivine into a mixture of silicate perovskite and ferropericlase and vice versa. In
11770-488: Was attributed to Seth, the spirit of evil who according to Egyptian tradition governed the central deserts of Africa. In the Black Pyramid of Abusir , dating before 2000 BC, Gaston Maspero found some pieces of iron. In the funeral text of Pepi I , the metal is mentioned. A sword bearing the name of pharaoh Merneptah as well as a battle axe with an iron blade and gold-decorated bronze shaft were both found in
11880-400: Was cheaper, stronger and lighter, and forged iron implements superseded cast bronze tools permanently. In Central and Western Europe, the Iron Age lasted from c. 800 BC to c. 1 BC , beginning in pre-Roman Iron Age Northern Europe in c. 600 BC , and reaching Northern Scandinavian Europe about c. 500 BC . The Iron Age in the Ancient Near East
11990-561: Was produced in southern India, by what would later be called the crucible technique . In this system, high-purity wrought iron, charcoal, and glass were mixed in a crucible and heated until the iron melted and absorbed the carbon. The protohistoric Early Iron Age in Sri Lanka lasted from 1000 BC to 600 BC. Radiocarbon evidence has been collected from Anuradhapura and Aligala shelter in Sigiriya . The Anuradhapura settlement
12100-458: Was somewhat delayed, and Northern Europe was not reached until about the start of the 5th century BC (500 BC). The Iron Age in India is stated as beginning with the ironworking Painted Grey Ware culture , dating from the 15th century BC , through to the reign of Ashoka in the 3rd century BC . The term "Iron Age" in the archaeology of South, East, and Southeast Asia is more recent and less common than for Western Eurasia. Africa did not have
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