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Tibetan Silver
Tibetan silver (Chinese ''Zangyin'') in modern usage refers to a variety of white non-precious metal alloys used primarily in jewelry components, with an appearance similar to aged silver. Description Silver in Tibet In ancient times silver was imported from regions near modern Iran ( Bactria, Khorasan), and an association of silverwork with Iran appears to have developed. Silver was imported from China (as ingots), India (''tankas''), and from Mongolia and Siberia. Some silver was mined in Tibet, but imports were required to satisfy the country's requirements for minting. In addition to coinage silver was used in Tibet for '' repousse'' work, and as an inlay in brass and copper statues. Historically 'Tibetan Silver' did contain silver, and some old items may be predominantly silver. Modern usage 'Tibetan Silver' includes copper-tin, and copper-nickel alloys; zinc alloys; and other alloy compositions, as well as base metals such as iron plated with a silver alloy. An X-ray fluor ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Silver
Silver is a chemical element with the symbol Ag (from the Latin ', derived from the Proto-Indo-European ''h₂erǵ'': "shiny" or "white") and atomic number 47. A soft, white, lustrous transition metal, it exhibits the highest electrical conductivity, thermal conductivity, and reflectivity of any metal. The metal is found in the Earth's crust in the pure, free elemental form ("native silver"), as an alloy with gold and other metals, and in minerals such as argentite and chlorargyrite. Most silver is produced as a byproduct of copper, gold, lead, and zinc refining. Silver has long been valued as a precious metal. Silver metal is used in many bullion coins, sometimes alongside gold: while it is more abundant than gold, it is much less abundant as a native metal. Its purity is typically measured on a per-mille basis; a 94%-pure alloy is described as "0.940 fine". As one of the seven metals of antiquity, silver has had an enduring role in most human cultures. Oth ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Iran
Iran, officially the Islamic Republic of Iran, and also called Persia, is a country located in Western Asia. It is bordered by Iraq and Turkey to the west, by Azerbaijan and Armenia to the northwest, by the Caspian Sea and Turkmenistan to the north, by Afghanistan and Pakistan to the east, and by the Gulf of Oman and the Persian Gulf to the south. It covers an area of , making it the 17th-largest country. Iran has a population of 86 million, making it the 17th-most populous country in the world, and the second-largest in the Middle East. Its largest cities, in descending order, are the capital Tehran, Mashhad, Isfahan, Karaj, Shiraz, and Tabriz. The country is home to one of the world's oldest civilizations, beginning with the formation of the Elamite kingdoms in the fourth millennium BC. It was first unified by the Medes, an ancient Iranian people, in the seventh century BC, and reached its territorial height in the sixth century BC, when Cyrus the Great f ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bactria
Bactria (; Bactrian: , ), or Bactriana, was an ancient region in Central Asia in Amu Darya's middle stream, stretching north of the Hindu Kush, west of the Pamirs and south of the Gissar range, covering the northern part of Afghanistan, southwestern Tajikistan and southeastern Uzbekistan. Called "beautiful Bactria, crowned with flags" by the Avesta, the region is one of the sixteen perfect Iranian lands that the supreme deity Ahura Mazda had created. One of the early centres of Zoroastrianism and capital of the legendary Kayanian kings of Iran, Bactria is mentioned in the Behistun Inscription of Darius the Great as one of the satrapies of the Achaemenid Empire; it was a special satrapy and was ruled by a crown prince or an intended heir. Bactria was the centre of Iranian resistance against the Macedonian invaders after the fall of the Achaemenid Empire in the 4th century BC, but eventually fell to Alexander the Great. After the death of Alexander, Bactria was annexed b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Greater Khorasan
Greater Khorāsān,Dabeersiaghi, Commentary on Safarnâma-e Nâsir Khusraw, 6th Ed. Tehran, Zavvâr: 1375 (Solar Hijri Calendar) 235–236 or Khorāsān ( pal, Xwarāsān; fa, خراسان ), is a historical eastern region in the Iranian Plateau between Western and Central Asia. The name ''Khorāsān'' is Persian and means "where the sun arrives from" or "the Eastern Province".Sykes, M. (1914). "Khorasan: The Eastern Province of Persia". ''Journal of the Royal Society of Arts'', 62(3196), 279-286.A compound of ''khwar'' (meaning "sun") and ''āsān'' (from ''āyān'', literally meaning "to come" or "coming" or "about to come"). Thus the name ''Khorasan'' (or ''Khorāyān'' ) means "sunrise", viz. " Orient, East"Humbach, Helmut, and Djelani Davari, "Nāmé Xorāsān", Johannes Gutenberg-Universität Mainz; Persian translation by Djelani Davari, published in Iranian Languages Studies Website. MacKenzie, D. (1971). ''A Concise Pahlavi Dictionary'' (p. 95). London: Oxford Univers ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
X-ray Fluorescence
X-ray fluorescence (XRF) is the emission of characteristic "secondary" (or fluorescent) X-rays from a material that has been excited by being bombarded with high-energy X-rays or gamma rays. The phenomenon is widely used for elemental analysis and chemical analysis, particularly in the investigation of metals, glass, ceramics and building materials, and for research in geochemistry, forensic science, archaeology and art objects such as paintings. Underlying physics When materials are exposed to short-wavelength X-rays or to gamma rays, ionization of their component atoms may take place. Ionization consists of the ejection of one or more electrons from the atom, and may occur if the atom is exposed to radiation with an energy greater than its ionization energy. X-rays and gamma rays can be energetic enough to expel tightly held electrons from the inner orbitals of the atom. The removal of an electron in this way makes the electronic structure of the atom unstable, and electro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nickel Allergy
Nickel allergy or nickel allergic contact dermatitis (Ni-ACD) is a form of allergic contact dermatitis (ACD) caused by exposure to the chemical element nickel. It typically causes a rash that is red and itchy and that may be bumpy or scaly. The main treatment is avoiding contact with nickel-releasing metals, such as inexpensive jewelry. Signs and symptoms The most common sign of nickel allergy is inflammation of the skin at an area that comes into regular contact with nickel. This often takes the form of a reddened patch of skin with raised bumps (papules) or small blisters (vesicles), and edema. People with chronic dermatitis tend to have dry, scaly, and cracked skin at the site of contact. These sites of inflammation (called "primary eruptions") can occur anywhere on the skin that contacts nickel, but are most common on the hands, face, or anywhere that contacts metal objects such as jewelry or metal clothes buttons. Particularly high levels of nickel exposure can cause irr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lead
Lead is a chemical element with the symbol Pb (from the Latin ) and atomic number 82. It is a heavy metal that is denser than most common materials. Lead is soft and malleable, and also has a relatively low melting point. When freshly cut, lead is a shiny gray with a hint of blue. It tarnishes to a dull gray color when exposed to air. Lead has the highest atomic number of any stable element and three of its isotopes are endpoints of major nuclear decay chains of heavier elements. Lead is toxic, even in small amounts, especially to children. Lead is a relatively unreactive post-transition metal. Its weak metallic character is illustrated by its amphoteric nature; lead and lead oxides react with acids and bases, and it tends to form covalent bonds. Compounds of lead are usually found in the +2 oxidation state rather than the +4 state common with lighter members of the carbon group. Exceptions are mostly limited to organolead compounds. Like the lighter members of the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Arsenic
Arsenic is a chemical element with the symbol As and atomic number 33. Arsenic occurs in many minerals, usually in combination with sulfur and metals, but also as a pure elemental crystal. Arsenic is a metalloid. It has various allotropes, but only the gray form, which has a metallic appearance, is important to industry. The primary use of arsenic is in alloys of lead (for example, in car batteries and ammunition). Arsenic is a common n-type dopant in semiconductor electronic devices. It is also a component of the III-V compound semiconductor gallium arsenide. Arsenic and its compounds, especially the trioxide, are used in the production of pesticides, treated wood products, herbicides, and insecticides. These applications are declining with the increasing recognition of the toxicity of arsenic and its compounds. A few species of bacteria are able to use arsenic compounds as respiratory metabolites. Trace quantities of arsenic are an essential dietary element in r ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Qing Dynasty
The Qing dynasty ( ), officially the Great Qing,, was a Manchu-led imperial dynasty of China and the last orthodox dynasty in Chinese history. It emerged from the Later Jin dynasty founded by the Jianzhou Jurchens, a Tungusic-speaking ethnic group who unified other Jurchen tribes to form a new "Manchu" ethnic identity. The dynasty was officially proclaimed in 1636 in Manchuria (modern-day Northeast China and Outer Manchuria). It seized control of Beijing in 1644, then later expanded its rule over the whole of China proper and Taiwan, and finally expanded into Inner Asia. The dynasty lasted until 1912 when it was overthrown in the Xinhai Revolution. In orthodox Chinese historiography, the Qing dynasty was preceded by the Ming dynasty and succeeded by the Republic of China. The multiethnic Qing dynasty lasted for almost three centuries and assembled the territorial base for modern China. It was the largest imperial dynasty in the history of China and in 1790 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Copper Alloys
Copper alloys are metal alloys that have copper as their principal component. They have high resistance against corrosion. The best known traditional types are bronze, where tin is a significant addition, and brass, using zinc instead. Both of these are imprecise terms, having both been commonly referred to as lattens in the past. Today the term ''copper alloy'' tends to be substituted, especially by museums. Composition The similarity in external appearance of the various alloys, along with the different combinations of elements used when making each alloy, can lead to confusion when categorizing the different compositions. There are as many as 400 different copper and copper alloy compositions loosely grouped into the categories: copper, high copper alloy, brasses, bronzes, copper nickels, copper–nickel–zinc (nickel silver), leaded copper, and special alloys. The following table lists the principal alloying element for four of the more common types used in mode ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
