Tumbaga is the name for a non-specific alloy of gold and copper given by Spanish Conquistadors to metals composed of these elements found in widespread use in pre-Columbian Mesoamerica and South America. The term is believed to be a borrowing from Malay tembaga, meaning "copper" or "brass", which in turn is from Prakrit. Tumbaga is an alloy composed of gold and copper, it has a lower melting point than gold or copper alone. It maintains malleability after being pounded. Tumbaga can be treated like citric acid, to dissolve copper off the surface. What remains is a shiny layer of nearly pure gold on top of a harder, more durable copper-gold alloy sheet; this process is referred to as depletion gilding. Tumbaga was used by the pre-Columban cultures of Central America to make religious objects. Like most gold alloys, tumbaga was versatile and could be cast, hammered, soldered, plated, annealed, engraved and inlaid; the proportion of gold to copper in artifacts varies widely. Some tumbaga has been found to be composed of metals besides gold and copper, up to 18% of the total mass of the tumbaga.
Tumbaga objects were made using a combination of the lost wax technique and depletion gilding. An alloy of varying proportions of copper and gold was cast. After removal it was burned, turning surface copper into copper oxide, mechanically removed The object was placed in an oxidizing solution composed of sodium chloride and ferric sulfate; this dissolved the silver from the surface. When viewed through a microscope, voids appear where the silver had been. In 1992 200 silver "tumbaga" bars were recovered in wreckage off Grand Bahama Island, they were composed of silver and gold plundered by the Spaniards during the conquests of Cortés and hastily melted into bars of tumbaga for transport across the Atlantic. Such bars were melted back into their constituent metals in Spain. Shipwreck recovered right after the conquest of Cortés with tumbaga gold bars The "Tumbaga" Saga: Treasure of the Conquistadors. Book about Tumbaga Bars The Art of Precolumbian Gold: The Jan Mitchell Collection, an exhibition catalog from The Metropolitan Museum of Art, which contains material on Tumbaga
Orichalcum or aurichalcum is a metal mentioned in several ancient writings, including the story of Atlantis in the Critias of Plato. Within the dialogue, Critias claims that orichalcum had been considered second only to gold in value and had been found and mined in many parts of Atlantis in ancient times, but that by Critias' own time orichalcum was known only by name. Orichalcum may have been a noble metal such as platinum, as it was supposed to be mined, or one type of bronze or brass or some other metal alloy. In 2015, metal ingots were found in an ancient shipwreck in Gela, which were made of an alloy consisting of copper and small percentages of nickel and iron. In numismatics, orichalcum is the golden-colored bronze alloy used by the Roman Empire for their sestertius and dupondius coins; the name is derived from the Greek ὀρείχαλκος, meaning "mountain copper". The Romans transliterated "orichalcum" as "aurichalcum", thought to mean "gold copper", it is known from the writings of Cicero that the metal which they called orichalcum resembled gold in color but had a much lower value.
In Virgil's Aeneid, the breastplate of Turnus is described as "stiff with gold and white orichalc". Orichalcum has been held to be either a gold-copper alloy, a copper-tin or copper-zinc brass, or a metal or metallic alloy no longer known. In years, "orichalcum" was used to describe the sulfide mineral chalcopyrite and to describe brass. However, these usages are difficult to reconcile with the claims of Plato's Critias, who states that the metal was "only a name" by his time, while brass and chalcopyrite were important in the time of Plato, as they still are today. Joseph Needham notes that 18th century Bishop Richard Watson, a professor of chemistry, wrote of an ancient idea that there were "two sorts of brass or orichalcum". Needham suggests that the Greeks may not have known how orichalcum was made, that they might have had an imitation of the original. In 2015, 39 ingots believed to be orichalcum were discovered in a sunken vessel on the coasts of Gela in Sicily which have tentatively been dated at 2,600 years old.
They were analyzed with X-ray fluorescence by Dario Panetta of Technologies for Quality and turned out to be an alloy consisting of 75-80 percent copper, 15-20 percent zinc, smaller percentages of nickel and iron. Orichalcum is first mentioned in the 7th century BC by Hesiod, in the Homeric hymn dedicated to Aphrodite, dated to the 630s. According to the Critias of Plato, the three outer walls of the Temple to Poseidon and Cleito on Atlantis were clad with brass and the third outer wall, which encompassed the whole citadel, "flashed with the red light of orichalcum"; the interior walls and floors of the temple were covered in orichalcum, the roof was variegated with gold and orichalcum. In the center of the temple stood a pillar of orichalcum, on which the laws of Poseidon and records of the first son princes of Poseidon were inscribed. Pliny the Elder points out. Pseudo-Aristotle in De mirabilibus auscultationibus describes a type of copper, "very shiny and white, not because there is tin mixed with it, but because some earth is combined and molten with it."
This might be a reference to orichalcum obtained during the smelting of copper with the addition of "cadmia", a kind of earth found on the shores of the Black Sea, attributed to be zinc oxide. In numismatics, the term "orichalcum" is used to refer to the golden-colored bronze alloy used for the sestertius and dupondius coins, it is considered more valuable than copper. Media related to Orichalcum coins at Wikimedia Commons
Electrum is a occurring alloy of gold and silver, with trace amounts of copper and other metals. It has been produced artificially, is known as green gold; the ancient Greeks called it'gold' or'white gold', as opposed to'refined gold'. Its colour ranges depending on the proportions of gold and silver; the gold content of occurring electrum in modern Western Anatolia ranges from 70% to 90%, in contrast to the 45–55% of gold in electrum used in ancient Lydian coinage of the same geographical area. This suggests that one reason for the invention of coinage in that area was to increase the profits from seigniorage by issuing currency with a lower gold content than the circulating metal. Electrum was used as early as the third millennium BCE in Old Kingdom of Egypt, sometimes as an exterior coating to the pyramidions atop ancient Egyptian pyramids and obelisks, it was used in the making of ancient drinking vessels. The first metal coins made were of electrum and date back to the end of the 7th century or the beginning of the 6th century BCE.
For several decades, the medals awarded with the Nobel Prize have been made of gold-plated green gold. The name "electrum" is the Latinized form of the Greek word ἤλεκτρον, mentioned in the Odyssey referring to a metallic substance consisting of gold alloyed with silver; the same word was used for the substance amber because of the pale yellow colour of certain varieties. It is from amber's electrostatic properties that the modern English words "electron" and "electricity" are derived. Electrum was referred to as "white gold" in ancient times, but could be more described as "pale gold", as it is pale yellow or yellowish-white in colour; the modern use of the term white gold concerns gold alloyed with any one or a combination of nickel, silver and palladium to produce a silver-coloured gold. Electrum consists of gold and silver but is sometimes found with traces of platinum and other metals; the name is applied informally to compositions between about 20–80% gold and 20–80% silver atoms, but these are called gold or silver depending on the dominant element.
Analysis of the composition of electrum in ancient Greek coinage dating from about 600 BCE shows that the gold content was about 55.5% in the coinage issued by Phocaea. In the early classical period, the gold content of electrum ranged from 46% in Phokaia to 43% in Mytilene. In coinage from these areas, dating to 326 BCE, the gold content averaged 40% to 41%. In the Hellenistic period, electrum coins with a decreasing proportion of gold were issued by the Carthaginians. In the Eastern Roman Empire controlled from Constantinople, the purity of the gold coinage was reduced, an alloy that can be called electrum began to be used. Electrum is mentioned in an account of an expedition sent by Pharaoh Sahure of the Fifth Dynasty of Egypt, it is discussed by Pliny the Elder in his Naturalis Historia. Electrum is mentioned in the Hebrew Scriptures, whose prophet Ezekiel is said to have had a vision of Jehovah on a celestial chariot; the earliest known electrum coins and East Greek coins found under the Temple of Artemis at Ephesus, are dated to the last quarter of the 7th century BCE.
Electrum is believed to have been used in coins c.600 BCE in Lydia during the reign of Alyattes. Electrum was much better for coinage than gold because it was harder and more durable, but because techniques for refining gold were not widespread at the time; the discrepancy between gold content of electrum from modern Western Anatolia and ancient Lydian coinage suggests that the Lydians had solved the refining technology for silver and were adding refined silver to the local native electrum some decades before introducing the pure silver coins cited below. In Lydia, electrum was minted into coins weighing 4.7 grams, each valued at 1/3 stater. Three of these coins—with a weight of about 14.1 grams )—totalled one stater, about one month's pay for a soldier. To complement the stater, fractions were made: the trite, the hekte, so forth, including 1/24 of a stater, down to 1/48 and 1/96 of a stater; the 1/96 stater was only about 0.14 grams to 0.15 grams. Larger denominations, such as a one stater coin, were minted as well.
Because of variation in the composition of electrum, it was difficult to determine the exact worth of each coin. Widespread trading was hampered by this problem, as the intrinsic value of each electrum coin could not be determined; these difficulties were eliminated circa 570 BCE when the Croeseids, coins of pure gold and silver were introduced. However, electrum currency remained common until 350 BCE; the simplest reason for this was that, because of the gold content, one 14.1 gram stater was worth as much as ten 14.1 gram silver pieces. Corinthian bronze – a prized alloy in antiquity, which may have contained electrum Hepatizon List of alloys Orichalcum – another distinct metal or alloy mentioned in texts from classical antiquity used to refer to brass Panchaloha Shakudō – a Japanese billon of gold and copper with a dark blue-purple patina Shibuichi – another Japanese alloy known for its patina Thokcha – an alloy of meteoric iron or "thunderbolt iron" used in Tibet Tumbaga – a similar material, originating in Pre-Columbian America Electrum lion coins of the ancient Lydians An image of the obverse of a Lydian coin made of electrum
Panchaloha called Panchadhatu or Panchdhatu is a term for traditional five-metal alloys of sacred significance, used for making Hindu temple murtis and jewelry. The composition is laid down in the Shilpa shastras, a collection of ancient texts that describe arts and their design rules and standards. Panchaloha is traditionally described as an alloy of gold, copper and iron as the major constituents. In some cases tin or lead is used instead of zinc, it is believed that wearing jewellery made of such an alloy brings balance in life, self-confidence, good health, fortune and peace of mind. In Tibetan culture, it was considered auspicious to use thokcha either as a component of the alloy in general or for a specific object or purpose; the amount used could vary, depending upon the material's availability and suitability, among other considerations. A small symbolic quantity of "sky-iron" might be added, or it might be included as a significant part of the alloy-recipe. Media related to Panchaloha at Wikimedia Commons Media related to Objects made from meteoritic iron at Wikimedia Commons The Lost-Wax Casting of Icons, Utensils and Other Items in South India, R.
M. Pillai, S. G. K. Pillai, A. D. Damodaran, October 2002, JOM
An alloy is a combination of metals and of a metal or another element. Alloys are defined by a metallic bonding character. An alloy may be a mixture of metallic phases. Intermetallic compounds are alloys with a defined crystal structure. Zintl phases are sometimes considered alloys depending on bond types. Alloys are used in a wide variety of applications. In some cases, a combination of metals may reduce the overall cost of the material while preserving important properties. In other cases, the combination of metals imparts synergistic properties to the constituent metal elements such as corrosion resistance or mechanical strength. Examples of alloys are steel, brass, duralumin and amalgams; the alloy constituents are measured by mass percentage for practical applications, in atomic fraction for basic science studies. Alloys are classified as substitutional or interstitial alloys, depending on the atomic arrangement that forms the alloy, they can be heterogeneous or intermetallic. An alloy is a mixture of chemical elements, which forms an impure substance that retains the characteristics of a metal.
An alloy is distinct from an impure metal in that, with an alloy, the added elements are well controlled to produce desirable properties, while impure metals such as wrought iron are less controlled, but are considered useful. Alloys are made by mixing two or more elements, at least one of, a metal; this is called the primary metal or the base metal, the name of this metal may be the name of the alloy. The other constituents may or may not be metals but, when mixed with the molten base, they will be soluble and dissolve into the mixture; the mechanical properties of alloys will be quite different from those of its individual constituents. A metal, very soft, such as aluminium, can be altered by alloying it with another soft metal, such as copper. Although both metals are soft and ductile, the resulting aluminium alloy will have much greater strength. Adding a small amount of non-metallic carbon to iron trades its great ductility for the greater strength of an alloy called steel. Due to its very-high strength, but still substantial toughness, its ability to be altered by heat treatment, steel is one of the most useful and common alloys in modern use.
By adding chromium to steel, its resistance to corrosion can be enhanced, creating stainless steel, while adding silicon will alter its electrical characteristics, producing silicon steel. Like oil and water, a molten metal may not always mix with another element. For example, pure iron is completely insoluble with copper; when the constituents are soluble, each will have a saturation point, beyond which no more of the constituent can be added. Iron, for example, can hold a maximum of 6.67% carbon. Although the elements of an alloy must be soluble in the liquid state, they may not always be soluble in the solid state. If the metals remain soluble when solid, the alloy forms a solid solution, becoming a homogeneous structure consisting of identical crystals, called a phase. If as the mixture cools the constituents become insoluble, they may separate to form two or more different types of crystals, creating a heterogeneous microstructure of different phases, some with more of one constituent than the other phase has.
However, in other alloys, the insoluble elements may not separate until after crystallization occurs. If cooled quickly, they first crystallize as a homogeneous phase, but they are supersaturated with the secondary constituents; as time passes, the atoms of these supersaturated alloys can separate from the crystal lattice, becoming more stable, form a second phase that serve to reinforce the crystals internally. Some alloys, such as electrum, an alloy consisting of silver and gold, occur naturally. Meteorites are sometimes made of occurring alloys of iron and nickel, but are not native to the Earth. One of the first alloys made by humans was bronze, a mixture of the metals tin and copper. Bronze was an useful alloy to the ancients, because it is much stronger and harder than either of its components. Steel was another common alloy. However, in ancient times, it could only be created as an accidental byproduct from the heating of iron ore in fires during the manufacture of iron. Other ancient alloys include pewter and pig iron.
In the modern age, steel can be created in many forms. Carbon steel can be made by varying only the carbon content, producing soft alloys like mild steel or hard alloys like spring steel. Alloy steels can be made by adding other elements, such as chromium, vanadium or nickel, resulting in alloys such as high-speed steel or tool steel. Small amounts of manganese are alloyed with most modern steels because of its ability to remove unwanted impurities, like phosphorus and oxygen, which can have detrimental effects on the alloy. However, most alloys were not created until the 1900s, such as various aluminium, titanium and magnesium alloys; some modern superalloys, such as incoloy and hastelloy, may consist of a multitude of different elements. As a noun, the term alloy is used to describe a mixture of atoms in which the primary constituent is a metal; when used as a verb, the term refers to the act of mixing a metal with other elements. The primary metal is called the matrix, or the solvent; the secondary constituents are called s
Japan is an island country in East Asia. Located in the Pacific Ocean, it lies off the eastern coast of the Asian continent and stretches from the Sea of Okhotsk in the north to the East China Sea and the Philippine Sea in the south; the kanji that make up Japan's name mean "sun origin", it is called the "Land of the Rising Sun". Japan is a stratovolcanic archipelago consisting of about 6,852 islands; the four largest are Honshu, Hokkaido and Shikoku, which make up about ninety-seven percent of Japan's land area and are referred to as home islands. The country is divided into 47 prefectures in eight regions, with Hokkaido being the northernmost prefecture and Okinawa being the southernmost one; the population of 127 million is the world's tenth largest. 90.7 % of people live in cities. About 13.8 million people live in the capital of Japan. The Greater Tokyo Area is the most populous metropolitan area in the world with over 38 million people. Archaeological research indicates; the first written mention of Japan is in Chinese history texts from the 1st century AD.
Influence from other regions China, followed by periods of isolation from Western Europe, has characterized Japan's history. From the 12th century until 1868, Japan was ruled by successive feudal military shōguns who ruled in the name of the Emperor. Japan entered into a long period of isolation in the early 17th century, ended in 1853 when a United States fleet pressured Japan to open to the West. After nearly two decades of internal conflict and insurrection, the Imperial Court regained its political power in 1868 through the help of several clans from Chōshū and Satsuma – and the Empire of Japan was established. In the late 19th and early 20th centuries, victories in the First Sino-Japanese War, the Russo-Japanese War and World War I allowed Japan to expand its empire during a period of increasing militarism; the Second Sino-Japanese War of 1937 expanded into part of World War II in 1941, which came to an end in 1945 following the Japanese surrender. Since adopting its revised constitution on May 3, 1947, during the occupation led by SCAP, the sovereign state of Japan has maintained a unitary parliamentary constitutional monarchy with an Emperor and an elected legislature called the National Diet.
Japan is a member of the ASEAN Plus mechanism, UN, the OECD, the G7, the G8, the G20, is considered a great power. Its economy is the world's third-largest by nominal GDP and the fourth-largest by purchasing power parity, it is the world's fourth-largest exporter and fourth-largest importer. Japan benefits from a skilled and educated workforce. Although it has renounced its right to declare war, Japan maintains a modern military with the world's eighth-largest military budget, used for self-defense and peacekeeping roles. Japan is a developed country with a high standard of living and Human Development Index, its population enjoys the highest life expectancy and third lowest infant mortality rate in the world, but is experiencing issues due to an aging population and low birthrate. Japan is renowned for its historical and extensive cinema, influential music industry, video gaming, rich cuisine and its major contributions to science and modern technology; the Japanese word for Japan is 日本, pronounced Nihon or Nippon and means "the origin of the sun".
The character nichi means "sun" or "day". The compound therefore means "origin of the sun" and is the source of the popular Western epithet "Land of the Rising Sun"; the earliest record of the name Nihon appears in the Chinese historical records of the Tang dynasty, the Old Book of Tang. At the end of the seventh century, a delegation from Japan requested that Nihon be used as the name of their country; this name may have its origin in a letter sent in 607 and recorded in the official history of the Sui dynasty. Prince Shōtoku, the Regent of Japan, sent a mission to China with a letter in which he called himself "the Emperor of the Land where the Sun rises"; the message said: "Here, I, the emperor of the country where the sun rises, send a letter to the emperor of the country where the sun sets. How are you". Prior to the adoption of Nihon, other terms such as Yamato and Wakoku were used; the term Wa is a homophone of Wo 倭, used by the Chinese as a designation for the Japanese as early as the third century Three Kingdoms period.
Another form of Wa, Wei in Chinese) was used for an early state in Japan called Nakoku during the Han dynasty. However, the Japanese disliked some connotation of Wa 倭, it was therefore replaced with the substitute character Wa, meaning "togetherness, harmony"; the English word Japan derives from the historical Chinese pronunciation of 日本. The Old Mandarin or early Wu Chinese pronunciation of Japan was recorded by Marco Polo as Cipangu. In modern Shanghainese, a Wu dialect, the pronunciation of characters 日本; the old Malay word for Japan, Japun or Japang, was borrowed from a southern coastal Chinese dialect Fukienese or Ningpo – and this Malay word was encountered by Portuguese traders in Southeast Asia in the 16th century. These Early Portuguese traders brought the word
Mokume-gane is a Japanese metalworking procedure which produces a mixed-metal laminate with distinctive layered patterns, as well as that laminate itself. Mokume gane translates to "wood grain metal" or "wood eye metal" and describes the way metal takes on the appearance of natural wood grain. Mokume gane fuses several layers of differently coloured precious metals together to form a sandwich of alloys called a "billet." The billet is manipulated in such a way that a pattern resembling wood grain emerges over its surface. Numerous ways of working the mokume gane create diverse pattens. Once the metal has been rolled into a sheet or bar, several techniques are used to produce a range of effects. Mokume-gane has been used to create many artistic objects. Though the technique was first developed for production of decorative sword fittings, the craft is today used in the production of jewelry and hollowware. First developed in 17th-century Japan, mokume-gane was used for swords; as the customary Japanese sword stopped serving as a weapon and became a status symbol, a demand arose for elaborate decorative handles and sheaths.
To meet this demand, Denbei Shoami, a master metalworker from Akita prefecture, invented the mokume gane process. He called his product guri bori for its simplest form's resemblance to guri, a type of carved lacquerwork with alternating layers of red and black. Other historical names for it were kasumi-uchi, itame-gane, yosefuki; the early components were soft metals and alloys which would form liquid phase diffusion bonds with one another without melting. This soldering the layers together. Over time, the practice of making mokume gane faded; the katana industry dried up in the late 19th century with Meiji Restoration returning ruling power to the emperor and the dissolution of the Shogunate government and the end of the Samurai class. The public display of swords as a sign of samurai status was outlawed. After this the few metalsmiths who practiced in mokume gane along with most other sword related artisans transferred their skills to create other objects. Tiffany & Co.'s silver division under the direction of Edward C. Moore began to experiment with mokume gane techniques around 1877 and at the Paris exposition of 1878 Tiffany's in its grand prize-winning display of Moore's "Japanesque" silver wares included a magnificent "Conglomerate Vase" with asymmetrical panels of mokume gane.
Moore and Tiffany's silver smiths continued to develop its popular mokume techniques in preparation for the Paris exposition of 1889 where it displayed a vast array of Japanesque silver using more complex alloys of shakado and shibuci along with gold and silver to make laminates of up to twenty-four layers. Tiffany's display again won the grand prize for silver wares, the company continued to produce its Japanesque silver with mokume up into the twentieth century. By the mid 20th century, mokume gane was entirely unknown. Japan’s movement away from traditional craftwork, paired with the great difficulty of mastering the mokume gane art, had brought mokume gane artisans to the brink of extinction, it reached a point where only collectors of metalwork were aware of the technique. It was not until the 1970s. Hiroko and her husband Eugene Pijanowski brought the craft of mokume gane back to the United States and began teaching it to their students, at this point the artform re-emerged in the public eye.
Today, flatware, spinning tops and other artistic objects are made using this material. Modern processes are controlled and include a compressive force on the billet; this has allowed the technique to include many nontraditional components such as titanium, iron, brass, nickel silver, various colors of karat gold including yellow, white and rose hues as well as sterling silver. At the Santa Fe Symposium, a major annual gathering of jewelers from around the world, there have been several papers presented on new, more predictable, more economic, methods of producing mokume gane materials, along with new possibilities for laminating metals such as the use of friction-stir welding. Metal sheets were stacked and heated. Successful lamination using the traditional process requires a skilled smith with a great deal of experience. Bonding in the traditional process is achieved when some or all of the alloys in the stack are heated to the point of becoming molten this liquid alloy is what fuses the layers together.
Careful heat control and skillful forging are required for this process. In attempting to recreate the appearance of traditional mokume gane some artisans tried brazing layers together; the sheets were soldered using some other brazing alloy. This technique joined the metals, but is difficult to perfect on larger sheets. Flux inclusions could be trapped or bubbles could form. Imperfections need to be cut out, the metal re-soldered; the brazed sheets do not display the ductility and work-ability of diffusion bonded material. The modernized process uses a controlled atmosphere in a temperature-controlled furnace. Mechanical aids such as a hydraulic press or torque plates are typically used to