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92-432: Azurite was the only natural blue pigment used in early China. Early China seems not to have used a natural purple pigment and was the first to develop a synthetic one. Han blue in its pure form is, as the name suggests, blue. Han purple in its pure form is actually a dark blue, that is close to indigo . It is a purple in the way the term is used in colloquial English , i.e., it is a color between red and blue . It

184-510: A catalyst in the decomposition of barium minerals and as a flux . The amount of lead is important. Too much lead (more than 5%) causes partial melting and glass formation above 1000 °C. The role of lead is: The preparation of Han blue using malachite , silica and witherite as raw minerals also releases carbon dioxide and water vapor as by-products according to the following reaction: The solid-state reaction to produce barium copper silicates starts at roughly 900 °C. Han purple

276-544: A prefecture ( 府 ,   fǔ ). This form still appears in the Latin name of the Catholic diocese of Xi'an , archidioecesis Singanensis . The name was later romanized as " Hsi-an " by Wade & Giles and as " Sianfu " or " Sian " by the imperial post office , both of which were common until the promulgation of pinyin. The area of present-day Xi'an has been the site of several important former Chinese cities. The capital of

368-550: A cloth over the face of a Fifth Dynasty (2494 to 2345 BCE) mummy also at Meidum and a number of Eighteenth Dynasty (1543–1292 BCE) wall paintings. Depending on the degree of fineness to which it was ground, and its basic content of copper carbonate, it gave a wide range of blues. It has been known as mountain blue , Armenian stone , and azurro della Magna ( blue from Germany in Italian ). When mixed with oil it turns slightly green. When mixed with egg yolk it turns green-grey. It

460-793: A dimension" under suitable conditions when it enters a new state, as a Bose-Einstein Condensate . The researchers noted that "We have shown, for the first time, that the collective behavior in a bulk three-dimensional material can actually occur in just two dimensions. Low dimensionality is a key ingredient in many exotic theories that purport to account for various poorly understood phenomena, including high-temperature superconductivity , but until now there were no clear examples of ' dimensional reduction ' in real materials," said Ian Fisher Other research team members alluded to potential applications to quantum computing. In conventional computers, electron charges transport information, but electron spin might in

552-890: A few miles to the north, is the station for the high-speed trains of the Zhengzhou–Xi'an High-Speed Railway . With 34 platforms, it is the largest railway station in Northwest China . Construction of the station began on September 19, 2008. The station was opened on January 11, 2011. As of May 2012, Xi'an North Station is served only by the fast (G-series and D-series) trains running on the Zhengzhou–Xi'an high-speed railway ; one of them continues south to Hankou . The city's other stations include Xi'an West , Xi'an East , Xi'an South , Sanmincun, and Fangzhicheng railway stations. Xi'an Railway Station covers 597,000 square meters (6,430,000 square feet ), has 5 passenger platforms, and 24 tracks. It provides 112 services to 80 000 people daily. Among

644-425: A green-black glass at around 1200°C. It becomes more purplish when ground. Han blue is more chemically and thermally stable. It does not break down in dilute acids, and becomes more bluish when ground. Manufacturing depends on the raw materials, their ratios, fluxes, temperature, atmosphere, and reaction time. Production seems to have been focused in northern China, around 200–300 km (120–190 mi) north of

736-499: A layered structure with silicate forming the structural framework. However, Han blue is more stable because of structural features such as Han purple and blue are similar in many of their physical properties, which allow them to be mixed, but they differ in their chemical properties. In 2006 scientists at Stanford, Los Alamos National Laboratory and the Institute for Solid State Physics (University of Tokyo), showed that Han purple "loses

828-586: A major source of the blues used by medieval painters. Lapis lazuli (the pigment ultramarine) was chiefly supplied from Afghanistan during the Middle Ages, whereas azurite was a common mineral in Europe at the time. Sizable deposits were found near Lyons, France. It was mined since the 12th century in Saxony , in the silver mines located there. Heating can be used to distinguish azurite from purified natural ultramarine blue,

920-487: A more expensive but more stable blue pigment, as described by Cennino D'Andrea Cennini . Ultramarine withstands heat, whereas azurite converts to black copper oxide. However, gentle heating of azurite produces a deep blue pigment used in Japanese painting techniques. Azurite pigment can be synthesized by precipitating copper(II) hydroxide from a solution of copper(II) chloride with lime ( calcium hydroxide ) and treating

1012-482: A popular collector's stone. The notion that specimens must be carefully protected from bright light, heat, and open air to retain their intensity of color over time may be an urban legend . Paul E. Desautels, former curator of gems and minerals at the Smithsonian Institution , has written that azurite is stable under ordinary storage conditions. While not a major ore of copper itself, the presence of azurite

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1104-492: A succession of names: Fengyuan ( 奉 元 ), Anxi ( 安西 , "Peaceful West") and Jingzhao ( 京 兆 ). The Ming name "Xi'an" was changed back to Xijing ("Western Capital", as above) between 1930 and 1943. The Lantian Man was discovered in 1963 in Lantian County , 50 km (31 mi) southeast of Xi'an, and dates back to at least 500,000 years before the present time. A 6,500-year-old Neolithic village, Banpo ,

1196-815: A variety of blue-purple shades. The pigments were used for: Some of the earliest examples of the use of the Han pigments are beads which date back to the Western Zhou period. The pigments are either present as compact bodies or in glazed layers. These are compact bodies (solid sticks/rods) with shades ranging from light blue to dark purple. The range of colors is due to varying proportions of Han blue, Han purple, and colorless material. They are thought to be pigment sticks which were traded then ground to be used as pigment bases in paints. They may have been of importance themselves, as ceremonial or bureaucratic items of importance. Han purple and Han blue were first used in paints in

1288-473: Is 23:00, for Line 1 is 23:30, and for Line 2 is 23:50. On December 30, 2008, a fire accident occurred that was extinguished within an hour and all workers evacuated safely. Sixty-six hours later, on January 2, another fire occurred at another station on Line 2. Xi'an's rail station, located just north of Xi'an's walled city, is one of the eight major national rail stations and the main rail hub of Shaanxi Province. The new Xi'an North railway station , situated

1380-480: Is 25 miles northwest of Xi'an city center, and 8 miles northeast of the center of Xianyang. China Eastern Airlines , Hainan Airlines and China Southern Airlines are the main airlines using the airport. Terminal 3 and the second runway were opened on May 3, 2012. Construction of Terminal 5 began in 2022 and is expected to be completed by 2025. Other than linking to most Chinese cities, the airport also has flights to several major Asian cities. One incident, however,

1472-471: Is 3.7 to 3.9. Characteristic of a carbonate, specimens effervesce upon treatment with hydrochloric acid. The combination of deep blue color and effervescence when moistened with hydrochloric acid are identifying characteristics of the mineral. The optical properties (color, intensity) of minerals such as azurite and malachite are characteristic of copper(II). Many coordination complexes of copper(II) exhibit similar colors. According to crystal field theory ,

1564-499: Is 6.7 times the size of the current Forbidden City and 11 times the size of the Vatican City. The original Xi'an city wall was started in 194 BC and took 4 years to finish. Upon completion, the wall measured 25.7 km (15.97 mi) in length and 12 to 16 m (39.37–52.49 ft) in thickness at the base, enclosing an area of 36 km (13.90 sq mi). In the year 190, amidst uprisings and rebellions just prior to

1656-503: Is a good surface indicator of the presence of weathered copper sulfide ores. It is usually found in association with the chemically similar malachite, producing a striking color combination of deep blue and bright green that is strongly indicative of the presence of copper ores. Azurite was known in the pre-classical ancient world . It was used in ancient Egypt as a pigment, obtained from mines in Sinai . Ancient Mesopotamian writers report

1748-468: Is also known by the names blue bice and blue verditer , though verditer usually refers to a pigment made by chemical process. Older examples of azurite pigment may show a more greenish tint due to weathering into malachite. Much azurite was mislabeled lapis lazuli , a term applied to many blue pigments. As chemical analysis of paintings from the Middle Ages improves, azurite is being recognized as

1840-734: Is basically parallel to Line 2 on its east except for the northern parts, runs from the North Square of the North Railway Station [Beikezhan (Beiguangchang)] to south (Hangtianxincheng) and was available publicly on December 26, 2018. Line 5 opened on December 28, 2020. This line is 41.6 kilometers long, with 31 stations from Matengkong to Chuangxingang. Line 16 opened on June 27, 2023, and is 15.03 kilometers long, and runs from Qinchuangyuanzhongxin to Shijingli with 9 stations. Four more lines are currently under construction, including an extension of Line 1. The subway system covers some of

1932-538: Is created by the presence of red copper (I) oxide (Cu 2 O) which is formed when Han purple decomposes (the red and blue making purple). The decomposition of Han purple to form copper (I) oxide is Above 1050 °C, the CuO copper (II) oxide breaks down to copper (I) oxide: Both Han purple and Han blue are barium copper silicates (containing barium , copper , silicon , and oxygen ). However, they differ in their formula, structure, and chemical properties. Han purple has

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2024-595: Is formed fastest. Han blue forms when an excess of silica is present and a longer reaction time is allowed. Early Chinese manufacture generally produced a mixture of Han blue and Han purple particles in various ratios, but pure colors were sometimes manufactured. Han blue could have been brought to a melt, but Han purple does not form a homogeneous melt, so it would have had to use a sintering process. Prolonged firing causes Han purple to break down and form Han blue: The temperature needed to be high (around 900–1000 °C) and kept at that temperature for long periods. Han purple

2116-520: Is in 1994, when China Northwest Airlines flight 2303 broke up in mid-air and crashed near Xi'an en route to Guangzhou. A maintenance error was responsible. All 160 people on board died. As of 2016 , it remains the deadliest airplane crash ever to occur in mainland China. Xi'an is home to contemporary Chinese stars such as Xu Wei , Zhang Chu and Zheng Jun . Yangrou paomo (flat bread soaked in lamb soup; simplified Chinese: 羊肉泡馍 ; traditional Chinese: 羊肉泡饃 ; pinyin: Yángròu pàomó )

2208-443: Is not known to exist in nature, due to the high affinity of the Cu ion for the hydroxide anion HO . Azurite crystallizes in the monoclinic system . Large crystals are dark blue, often prismatic. Azurite specimens can be massive to nodular or can occur as drusy crystals lining a cavity. Azurite has a Mohs hardness of 3.5 to 4. The specific gravity of azurite

2300-493: Is not, however, a purple in the way the term is used in color science , i.e. a nonspectral color between red and violet on the 'line of purples' on the CIE chromaticity diagram . Perhaps the most accurate designation for the color would be to call it 'Han indigo', although it could also be regarded as a bright shade of ultramarine (classifying ultramarine as a color and not a pigment). The purple color seen in samples of Han purple

2392-455: Is the atonal pinyin romanization of its Chinese name 西安 , Western Peace . (The apostrophe – known in Chinese as a 隔音符號 , géyīn fúhào – should be included to distinguish its pronunciation from the single syllable xian .) The name was adopted in 1369 under the early Ming dynasty . Jesuit missionaries recorded its name as " Si-ngan " or "Si-ngan-fou" from its status as the seat of

2484-401: Is thermally sensitive, so temperature control for producing Han purple needed to be fairly constant (± 50 °C) . Han blue is thermally less sensitive. Under the right conditions, the manufacture of Han purple would have taken around 10–24 hours, while Han blue would have taken twice as long. Temperature would have been controlled by testing of firing materials, the size, shape, and material of

2576-531: Is urban. Xi'an has direct jurisdiction over 11 districts and 2 counties : Xi'an has many areas that are easily accessible on foot. In many commercial, residential, educational zones in the city, especially in the shopping and entertainment districts around the Bell Tower, underpasses and overpasses have been built for the safety and convenience of pedestrians. A bicycle sharing network started operating in Xi'an from

2668-497: Is used by pigment maker to lower the melting point of the barium in Han Purple. The increase and decrease of barium glasses, and Han purple and Han blue, follow similar patterns. Both peaked in the Han dynasty , declining afterwards. Pre-Han to Tang dynasties see a shift from lead-barium-silicate type glass to lead-soda-lime glass. The reason for decline is debatable. Liu et al. attribute

2760-593: The Giant Wild Goose Pagoda began in 652. This pagoda was 64 m (209.97 ft) in height, and was built to store the translations of Buddhist sutras obtained from India by Xuanzang . In 707, construction of the Small Wild Goose Pagoda began. This pagoda measured 45 m (147.64 ft) tall at the time of completion, and was built to store the translations of Buddhist sutras by Yijing . The massive 1556 Shaanxi earthquake eventually damaged

2852-583: The Guanzhong plain, the city is the third-most populous city in Western China after Chongqing and Chengdu , as well as the most populous city in Northwestern China . Its total population was 12.95 million as of the 2020 census, including an urban population of 9.28 million. Known as Chang'an throughout much of its history, Xi'an is one of China's Four Great Ancient Capitals , having held

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2944-561: The Han dynasty established his capital in Chang'an County; his first palace, Changle Palace ( 長樂宮 , "Perpetual Happiness") was built across the river from the ruin of the Qin capital. This is traditionally regarded as the founding date of Chang'an. Two years later, Liu Bang built Weiyang Palace ( 未央宮 , "Never Ending Palace") north of modern Xi'an. Weiyang Palace was the largest palace ever built on Earth, covering 4.8 square kilometers (1,200 acres), which

3036-505: The Three Kingdoms period, Dong Zhuo , a powerful warlord from nearby Xiliang, moved the court from Luoyang to Chang'an in a bid to avoid a coalition of other powerful warlords against him. In 582, shortly after the Sui dynasty was founded, the emperor of Sui ordered a new capital to be built southeast of the Han capital, called Daxing (大興, "Great prosperity"). It consisted of three sections:

3128-637: The Ural and Altai Mountains ; Sardinia ; Laurion, Greece ; Wallaroo, South Australia ; Brazil and Broken Hill . Azurite is unstable in air, however it was used as a blue pigment in antiquity. Azurite is naturally occurring in Sinai and the Eastern Desert of Egypt. It was reported by F. C. J. Spurrell (1895) in the following examples; a shell used as a pallet in a Fourth Dynasty (2613 to 2494 BCE) context in Meidum ,

3220-629: The Warring States period , China was unified under the Qin dynasty (221–206 BC) for the first time, with the capital located at Xianyang , just northwest of modern Xi'an. The first emperor of China, Qin Shi Huang ordered the construction of the Terracotta Army and his mausoleum just to the east of Xi'an almost immediately after his ascension to the throne. In 202 BC, the founding emperor Liu Bang of

3312-641: The Western Zhou were the twin cities of Feng and Hao , known collectively as Fenghao , located on opposite banks of the Feng River at its confluence with the southern bank of the Wei in the western suburbs of present-day Xi'an. The Qin capital Xianyang was erected north of the Wei during the Warring States period and was succeeded by the Western Han capital of Chang'an ( 長安 ), meaning "Perpetual Peace", which

3404-449: The Zhou dynasty . The capital of Zhou was established in the twin settlements of Fengjing ( 灃京 ) and Haojing ( 鎬京 ), together known as Fenghao , located southwest of contemporary Xi'an. The settlement was also known as Zōngzhōu (宗周) to indicate its role as the capital of the vassal states . In 738 BC, King Ping of Zhou moved the capital to Luoyang due to political unrest . Following

3496-406: The chemical formula BaCuSi 2 O 6 . Han purple has a layered structure with isolated 4-ring silicates , and contains a copper-copper bond which makes the compound more unstable than Han blue (metal-metal bonds are rare). Han blue has the chemical formula BaCuSi 4 O 10 . In 1993, it was discovered to occur naturally as the rare mineral effenbergerite . Han blue, like Han purple, has

3588-403: The kiln , and the control of the environment. Technology for achieving and maintaining high temperatures would have been known from metal and ceramic production e.g. the potential use of twin bellows as used in metal production. Han blue and Egyptian blue have the same basic structure and have very similar properties. The main difference is that Egyptian blue (CaCuSi 4 O 10 ) has calcium in

3680-649: The oxidized zone of copper ore deposits. Here they are associated with cuprite , native copper , and various iron oxide minerals. Fine specimens can be found at many locations. Among the best specimens are found at Bisbee, Arizona , and nearby locations, and have included clusters of crystals several inches long and spherical aggregates and rosettes up to 2 inches (51 mm) in diameter. Similar rosettes are found at Chessy, Rhône , France. The best crystals, up to 10 inches (250 mm) in length, are found at Tsumeb , Namibia . Other notable occurrences are in Utah ; Mexico ;

3772-594: The 1770s and Manchus from Xi'an garrison fought in other campaigns against the Dzungars and Uyghurs throughout the 1690s and 18th century. In the 1720s Jingzhou, Hangzhou, and Nanjing Manchu banner garrisons fought in Tibet. For the over 200 years they lived next to each other, Han civilians and Manchu bannermen of both genders in Xi'an did not intermarry with each other at all. The Qing dynasty altered its law on intermarriage between Han civilians and Manchu bannermen several times in

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3864-505: The 1980s, as part of the economic growth of inland China especially for the central and northwest regions, Xi'an has matured into a cultural, industrial, political and educational, and research and development hub. Xi'an currently holds sub-provincial status, administering 11 districts and 2 counties. In 2020, Xi'an was ranked as a Beta- (global second tier) city by the Globalization and World Cities Research Network , and, according to

3956-789: The Chinese city were cut down as they emerged from the gates." In 1936, the Xi'an (then "Sian") Incident took place in the city during the Chinese Civil War . The incident helped to bring the Kuomintang (KMT) and Chinese Communist Party to form the Second United Front in order to concentrate on fighting against the Imperial Japanese Army in the Second Sino-Japanese War . On March 11, 1938, an aerial battle broke out for

4048-538: The Geodetic Origin would be in central mainland China.' Lintong ( 临潼 ), a town near Xi'an was chosen. Since 1986, Chinese Standard Time (CST) was set from NTSC. The National Time Service Center (NTSC), the Chinese Academy of Sciences is an institute which is mainly engaged in the service and research on time and frequency. NTSC takes charge of generating and maintaining the national standard time scale, disseminating

4140-792: The Han dynasty, e.g. a bowl and top of a steamer, were decorated with Han purple. Due to the instability of Han purple, it shows significant signs of weathering on archaeologically excavated artifacts. The copper(I) oxide formed in the decomposition of Han purple (see section on color) remains stable, but Han purple continues to deteriorate, and its purple color increases with time. Han purple fades in acid, so colorless particles found in pigments containing Han blue and Han purple may be particles which were originally purple, but which faded in acidic conditions in burial. In addition, Han blue has fungicidal properties, so preserves better. Han purple reacts with oxalic acid to form BaCu(C 2 O 4 ) 2 . The light blue color of this coordination polymer may explain

4232-679: The Heaven'. Xi'an has a temperate climate that is influenced by the East Asian monsoon , classified under the Köppen climate classification as a borderline humid subtropical and humid continental climate ( Cwa/Dwa ). The Wei River valley is characterized by hot, humid summers, cold, dry winters, and dry springs and autumns. Most of the annual precipitation is delivered from July to late October. Snow occasionally falls in winter but rarely settles for long. Dust storms often occur during March and April as

4324-577: The Imperial City, the palace section, and the civilian section, with a total area of 84 km (32 sq mi) within the city walls. At the time, it was the largest city in the world. The city was renamed Chang'an by the Tang dynasty . In the mid-7th century, after returning from his pilgrimage to India, the Buddhist monk Xuanzang established a translation school for Sanskrit scriptures. Construction of

4416-436: The Latin name caeruleum . Copper (Cu ) gives it its blue color. Azurite has the formula Cu 3 (CO 3 ) 2 (OH) 2 , with the copper(II) cations linked to two different anions, carbonate and hydroxide . It is one of two relatively common basic copper(II) carbonate minerals , the other being bright green malachite . Aurichalcite is a rare basic carbonate of copper and zinc . Simple copper carbonate (CuCO 3 )

4508-438: The Qin dynasty. Han purple was used for the Terracotta Army in the tomb of Emperor Qin Shi Huang —the expense of producing Han purple and other pigments in such large quantities would have emphasized luxury and status. Han purple seems to have mostly been used on the trousers (pants) of the warriors. The pigment was bound to the terracotta surface with lacquer . The warriors were fired at the same temperature as that needed for

4600-514: The Song dynasty proper and its continued relevance to Muslim travelers into China and Chinese Muslim residents. During the Ming dynasty , a new wall was constructed in 1370 which remains intact to this day. The wall measures 11.9 km (7.4 mi) in circumference , 12 m (39.37 ft) in height, and 15 to 18 m (49.21–59.06 ft) in thickness at the base; a moat was also built outside

4692-905: The Tang Emperor Taizong , due to efforts of the Christian missionary Alopen in 635. Chang'an was devastated at the end of the Tang dynasty in 904. Residents were forced to move to the new capital city in Luoyang , and a small area in the city continued to be occupied thereafter. In the era of the Song dynasty , Xi'an was an important cultural center of scholarship and innovation on matters such as science , as well as historiography , religion, and philosophy in China. The Northern Song era saw its people, political culture , and strategic location be directly utilized by

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4784-453: The above equation, the conversion of azurite into malachite is attributable to the low partial pressure of carbon dioxide in air. Azurite is quite stable under ordinary storage conditions, so that specimens retain their deep blue color for long periods of time. Azurite is found in the same geologic settings as its sister mineral, malachite, though it is usually less abundant. Both minerals occur widely as supergene copper minerals, formed in

4876-586: The bannermen trying to steal at the markets. Manchu Lieutenant general Cimbru reported this to Yongzheng emperor in 1729, after he was assigned there. Governor Yue Rui of Shandong was then ordered by the Yongzheng to report any bannerman misbehaving and warned him not to cover it up in 1730, after Manchu bannermen were put in a quarter in Qingzhou. Manchu bannermen from the garrisons in Xi'an and Jingzhou fought in Xinjiang in

4968-486: The census data from 2007, the population has increased by 1.4 million persons. The population is 51.66 percent male and 48.34 percent female. Among its districts, Yanta has the largest population, with around 1.08 million inhabitants. The Xi'an metropolitan area was estimated by the OECD (Organisation for Economic Co-operation and Development) to have, as of 2010 , a population of 12.9 million, of which 5,740,000

5060-475: The city of Xi'an . This is the area with large deposits of raw materials. No written records have been found about the production of Han purple or Han blue, so information about manufacture has been achieved through experimentation. The raw materials needed are a barium mineral, quartz , a copper mineral, and a lead salt. It is unknown whether minerals were used in their natural form or were treated, though no evidence exists as yet of treatment. The barium source

5152-521: The city of Xi'an from the Kuomintang force. During the Mao era, Xi'an was further developed as part of the Third Front Construction . Xi'an made headlines for being one of the many cities where the 2012 China anti-Japanese demonstrations occurred. In 2022, Xi'an witnessed the largest COVID-19 community outbreak since the initial months of the pandemic hit China. From December 23, 2021,

5244-550: The city rapidly warms up. Summer months also experience frequent but short thunderstorms . The monthly 24-hour average temperature ranges from around the freezing mark in January to 27.0 °C (80.6 °F) in July, with an annual mean of 14.08 °C (57.3 °F). Extremes since 1951 have ranged from −20.6 °C (−5 °F) on January 11, 1955, to 41.8 °C (107 °F) on June 21, 1998. A highest record of 42.9 °C (109 °F)

5336-511: The city was put into strict lockdown after local authorities reported more than 250 cases, traced to the Delta variant by authorities. This led to stressed healthcare and delayed or insufficient food deliveries to some part of the city. Restrictions of Xi'an were lifted on January 24. Xi'an lies on the Guanzhong Plain in the south-central part of Shaanxi province, on a flood plain created by

5428-418: The color results from low energy d-d transitions associated with the d metal center. Azurite is unstable in open air compared to malachite, and often is pseudomorphically replaced by malachite . This weathering process involves the replacement of some of the carbon dioxide (CO 2 ) units with water (H 2 O), changing the carbonate:hydroxide ratio of azurite from 1:1 to the 1:2 ratio of malachite: From

5520-588: The country's own ranking, ranked 17th; it is also one of the world's top 100 financial centers according to the Global Financial Centres Index . Xi'an is ranked by the Nature Index as one the top 20 cities globally by scientific research output, and is home to multiple prestigious educational institutions , such as Xi'an Jiaotong University , Northwestern Polytechnical University , Xidian University and Northwest University . name "Xi'an"

5612-619: The decline to the decline of Taoism when Confucianism was introduced, since they link pigment manufacture to the ideology of Taoism. Berke (2007) believes that political changes stopped the distribution of the pigments as the Chinese Empire was split at the end of the Han period. Han blue seems to have been favored in earlier ( Zhou ) periods, and Han purple in later periods ( circa 400 BC). The Han pigments consist of varying combinations of blue, purple and colorless components. The grinding together of Han purple and Han blue would have allowed

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5704-406: The destinations served by direct trains from Xi'an are Beijing , Zhengzhou , Lanzhou , Baoji , and Mount Hua . China Railway High-speed 2 now run an express services from Xi'an to Baoji and Xi'an to Zhengzhou; with a total running time to Baoji of under 90 minutes, and 2 hours to Zhengzhou. The Zhengzhou–Xi'an high-speed railway also serves Xi'an. Construction work began on September 25, 2005,

5796-575: The dynasty. At the beginning of the Qing dynasty, the Qing allowed Han civilians to marry Manchu women. Then the Qing banned civilians from marrying women from the Eight banners later. In 1865, the Qing allowed Han civilian men to marry Manchu bannerwomen in all garrisons, except the capital garrison of Beijing. There was no formal law on marriage between people in the different banners, like the Manchu and Han banners, but it

5888-544: The early 19th century, it was also known as chessylite , after the type locality at Chessy-les-Mines near Lyon , France . The mineral, a basic carbonate with the chemical formula Cu 3 (CO 3 ) 2 (OH) 2 , has been known since ancient times, and was mentioned in Pliny the Elder 's Natural History under the Greek name kuanos (κυανός: "deep blue," root of English cyan ) and

5980-621: The eight surrounding rivers and streams. The city borders the northern foot of the Qin Mountains (Qinling) to the south, and the banks of the Wei River to the north. Hua Shan , one of the five sacred Taoist mountains, is located 100 km (62 mi) away to the east of the city. Not far to the north is the Loess Plateau . At the beginning of Han dynasty, the Chief of Staff Zhang Liang advised

6072-402: The emperor Liu Bang to choose Guanzhong as the capital of the Han dynasty: "Guanzhong Plain is located behind Mount Xiao and Hangu Pass , and connects Long ( Gansu ) and Shu ( Sichuan ). The area can be called an irony castle spreads for thousands of miles, and is rich in harvest like the nation of heaven." ( 关中左崤函，右陇蜀，沃野千里，此所谓金城千里，天府之国也 ) Since then, Guanzhong is also known as the 'Nation of

6164-626: The exact chronology of the invention of these blue pigments can be summarized as follows: The case against links with Egyptian blue includes the absence of lead in Egyptian blue and the lack of examples of Egyptian blue in China. The use of quartz, barium, and lead components in ancient Chinese glass and Han purple and Han blue has been used to suggest a connection between glassmaking and the manufacture of pigments, and to argue for independent Chinese invention. Taoist alchemists may have developed Han purple from their knowledge of glassmaking. The lead

6256-446: The first time over Xi'an as Imperial Japanese Army Air Force aircraft attacked the city, and was engaged by Chinese Air Force I-15 fighter planes, led by Lt. Cen Zeliu of the 5th Pursuit Group, 17th Squadron. While repeatedly attacked by air, Shaanxi was heavily fortified by units of the Eighth Route Army ; Xi'an was never taken by the Japanese forces. On May 20, 1949, the Communist-controlled People's Liberation Army captured

6348-434: The future play a similar role in " spintronic " devices: "Spin currents are capable of carrying far more information than a conventional charge current—which makes them the ideal vehicle for information transport in future applications such as quantum computing ," stated first author Suchitra Sebastian. Noted Fisher: "Our research group focuses on new materials with unconventional magnetic and electronic properties. Han Purple

6440-585: The growing number of personal automobiles also means traffic jams are a common urban issue. Line 2, running through the city from north (North Railway Station) to south (Weiqu Nan), was the first line opened to the public on September 16, 2011. Operations began on September 28, 2011. This line is 19.9 kilometers (12.4 miles) long with 17 stations. Line 1 opened on September 15, 2013. As a west–east railway, its 19 stations connect Houweizhai and Fangzhicheng . Line 3 runs from northeast ( Baoshuiqu ) to southwest (Yuhuazhai) and opened on November 8, 2016. Line 4, which

6532-408: The light blue color of some of the Terracotta Warriors' trousers – the color resulting from the presence of oxalate -excreting lichens. Two other synthetic blue barium copper silicate compounds have been found in trace amounts, but are as yet unnamed. They are Azurite Azurite or Azure spar is a soft, deep-blue copper mineral produced by weathering of copper ore deposits. During

6624-598: The manufacture of Han purple (950–1,050 °C [1,740–1,920 °F]), so the same kilns may have been used for both processes. No evidence indicates Han blue being used for the warriors ( azurite was used for the blue). Smaller painted pottery figurines have been found e.g. the Western Han dynasty Chu Tombs, Xuzhou , Jiangsu Province and in the Han dynasty Yangling tombs of Emperor Liuqi and his Empress (156–141 BC). Han blue and Han purple were used to decorate Han dynasty Hu dark grey pottery vessels. Bronze vessels in

6716-412: The massacre commented that "Old and young, men and women, children alike, were all butchered... Houses were plundered and then burnt; those who would fain have laid hidden till the storm was past, were forced to come out into the open. The revolutionaries, protected by a parapet of the wall, poured a heavy, unceasing, relentless fire into the doomed Tartar (Manchu) city, those who tried to escape thence into

6808-546: The most famous attractions, such as Banpo Museum (Banpo Station, Line 1), Bell and Drum Tower (Line 2), Fortifications of Xi'an (Line 2), the Giant Wild Goose Pagoda (Line 3 and Line 4), the Daminggong National Heritage Park (Line 4) and Shaanxi History Museum (Line 2, 3 and 4), etc. The first metro departure time for Line 1, 2, 3 and 4 is 6:00, the last metro departure time for Line 3 and 4

6900-499: The most militarily skilled provincial Manchu banner garrison. Manchu women from the Xi'an garrison often left the walled Manchu garrison and went to hot springs outside the city, and gained bad reputations for their sexual lives. A Manchu from Beijing, Sumurji, was shocked and disgusted by this after being appointed Lieutenant general of the Manchu garrison of Xi'an and informed the Yongzheng emperor what they were doing. Han civilians and Manchu bannermen in Xi'an had bad relations, with

6992-466: The position of Han blue's barium (BaCuSi 4 O 10 ). The similarity led some to suggest that Han blue was based on Egyptian blue knowledge, which had traveled east along the Silk Road . Independent innovation in China would still have been needed to replace calcium with barium (the Han pigments start to form at 100 – 200°C higher than the Egyptian blue). The two hypotheses underlying the speculations about

7084-505: The position under several of the most important dynasties in Chinese history , including the Western Zhou , Western Han , Sui , Northern Zhou and Tang . Xi'an is now the second-most popular tourist destination in China. The city was one of the terminal points on the Silk Road during the ancient and medieval eras, as well as the home of the 3rd-century BC Terracotta Army commissioned by Emperor Qin Shi Huang —both of which are listed as World Heritage Sites by UNESCO . Since

7176-494: The precipitate with a concentrated solution of potassium carbonate and lime. This pigment is likely to contain traces of basic copper(II) chlorides. Azurite is used occasionally as beads and as jewelry , and also as an ornamental stone. However, its softness and tendency to lose its deep blue color as it weathers leaves it with fewer uses. Heating destroys azurite easily, so all mounting of azurite specimens must be done at room temperature. The intense color of azurite makes it

7268-402: The provincial garrisons and they were able to draw their bows properly and perform cavalry archery, unlike Beijing Manchus. The Qianlong emperor received a memorial staying Xi'an Manchu bannermen still had martial skills, although not up to those, in the past in a 1737 memorial from Cimbu. By the 1780s, the military skills of Xi'an Manchu bannermen dropped enormously, and they had been regarded as

7360-417: The railway opened for service on February 6, 2010. The railway has made air service between Zhengzhou and Xi'an uncompetitive. All passenger flights between the two cities were suspended within 48 days of start of regular high-speed rail service. Xi'an Xianyang International Airport (airport code: XIY) is the major airport serving the city and it is the largest airport in the northwestern part of China. It

7452-590: The revolution. Those of Shaanxi supported the revolutionaries, while those of Gansu supported the Qing. The Hui of Xi'an (Shaanxi province) joined the Han Chinese revolutionaries in slaughtering the Manchus. Some wealthy Manchus survived by being ransomed . Wealthy Han Chinese enslaved Manchu girls and poor Han Chinese troops seized young Manchu women as wives. Hui Muslims also seized young pretty Manchu girls and raised them as Muslims. A British missionary who witnessed

7544-416: The time and frequency signals. The autonomous standard time scales of universal time and atomic time and the dissemination techniques with LF radio and HF radio were established successively during the 1970s and 1980s, which meet all the requirements for different applications on the whole, such as the scientific researches, national economy, etc. As of 2010 Xi'an has a population of 5.4 million. Compared to

7636-444: The tower and reduced its height to 43.4 m (142.39 ft). The Nestorian Stele is a Tang Chinese stele erected in 781 that documents 150 years of early Christianity in China . It is a 279 cm tall limestone block with text in both Chinese and Syriac describing the existence of Christian communities in several cities in northern China. It reveals that the initial Nestorian Christian church had met recognition by

7728-556: The use of a special mortar and pestle for grinding it. It was also used in ancient Greece , for example on the Acropolis in Athens. It does not appear to have been used in ancient Roman wall paintings but Roman writers certainly knew about its use as a pigment. The fusing of glass and azurite was developed in ancient Mesopotamia. Xi%27an Xi'an is the capital of the Chinese province of Shaanxi . A sub-provincial city on

7820-598: The walls. The new wall and moat would protect a much smaller city of 12 km (4.6 sq mi). The Qing dynasty established a walled off Manchu banner quarter in northeast Xi'an, on the site of the former palace of the Ming Prince of Qin. A Han banner quarter was established in the southeast of the city. Manchu bannermen from the Xi'an banner garrison were praised for maintaining Manchu culture by Kangxi in 1703. Xi'an garrison Manchus were said to retain Manchu culture far better than all other Manchus at martial skills in

7912-504: The year 2013 and today has 52,000 bikes, used by over 200,000 people per day. Taxi services are numerous, but many citizens of Xi'an still commute to work using the city's 270 official municipal bus routes serviced by a fleet of over 7,800 buses, with an average system-wide ridership of over 4 million people per day. The bus network is complemented by a rapidly expanding subway system that carries over 1.5 million commuters per day. There are more than 2 million registered automobiles in Xi'an;

8004-399: Was discovered in 1953 on the eastern outskirts of the city proper, which contains the remains of several well organized Neolithic settlements carbon dated to 5,600–6,700 years ago . The site is now home to the Xi'an Banpo Museum , built in 1957 to preserve the archaeological collection. Xi'an became a cultural and political center of China in the 11th century BC with the founding of

8096-434: Was either witherite (BaCO 3 ) or baryte (BaSO 4 ). The rarity of witherite may favor baryte as the most likely source. Baryte has a slower decomposition rate and so favors Han blue production. Witherite conversely favors Han purple. In the use of baryte, lead salts ( lead carbonate or lead oxide ) would have been needed to increase yield. Lead has been detected in association with Han purple and Han blue. Lead acts as

8188-412: Was first synthesized over 2,500 years ago, but we have only recently discovered how exotic its magnetic behavior is. It makes you wonder what other materials are out there that we haven't yet even begun to explore." Han purple is chemically and thermally less stable than Han blue. It fades and decomposes in dilute acid . Han purple starts to decompose at temperatures more than 1050–1100 °C and forms

8280-615: Was informally regulated by social status and custom. In northeastern China, such as Heilongjiang and Liaoning, it was more common for Manchu women to marry Han men, since they were not subjected to the same laws and institutional oversight as Manchus and Han in Beijing and elsewhere. In October 1911, during the Xinhai revolution , revolutionaries stormed the Manchu fort in Xi'an. Most of the city's 20,000 Manchus were killed. Hui (Muslims; then referred to as "Mohammedans") were divided in its support for

8372-613: Was located south of the Wei and covered the central area of present-day Xi'an. During the Eastern Han , Chang'an was also known as the "Western Capital" ( 西 京 ), named for its namesake position relative to the main capital at Luoyang . Under the Sui , its name became Daxing ( 大 興 , "Greatly Prosperous") in AD 581. Under the Tang , the name reverted to Chang'an in 618. Under the Mongolian Yuan dynasty (13th & 14th centuries), it held

8464-541: Was registered in another station on June 17, 2006. An unofficial record low of −25.0 °C (−13 °F) was also recorded in January 1930, but at another weather station in the northern suburbs of the city. The Shaanxi Astronomical Observatory was established in 1966. In 1975, according to the Geodetic Origin Report of the People's Republic of China, 'in order to avoid bias in the mensuration as much as possible,

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