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74-507: Liquid oxygen has a clear cyan color and is strongly paramagnetic : it can be suspended between the poles of a powerful horseshoe magnet . Liquid oxygen has a density of 1.141 kg/L (1.141 g/ml), slightly denser than liquid water, and is cryogenic with a freezing point of 54.36 K (−218.79 °C; −361.82 °F) and a boiling point of 90.19 K (−182.96 °C; −297.33 °F) at 1 bar (15 psi). Liquid oxygen has an expansion ratio of 1:861 and because of this, it

148-655: A dominant wavelength that's between approximately 450 and 495  nanometres . Most blues contain a slight mixture of other colours; azure contains some green, while ultramarine contains some violet. The clear daytime sky and the deep sea appear blue because of an optical effect known as Rayleigh scattering . An optical effect called the Tyndall effect explains blue eyes . Distant objects appear more blue because of another optical effect called aerial perspective . Blue has been an important colour in art and decoration since ancient times. The semi-precious stone lapis lazuli

222-515: A French chemist, Louis Jacques Thénard , made a synthetic cobalt blue pigment which became immensely popular with painters. In 1824 the Societé pour l'Encouragement d'Industrie in France offered a prize for the invention of an artificial ultramarine which could rival the natural colour made from lapis lazuli. The prize was won in 1826 by a chemist named Jean Baptiste Guimet, but he refused to reveal

296-523: A color name in English was in 1879. Further origins of the color name can be traced back to a dye produced from the cornflower ( Centaurea cyanus ). In most languages, 'cyan' is not a basic color term and it phenomenologically appears as a greenish vibrant hue of blue to most English speakers. Other English terms for this "borderline" hue region include blue green , aqua , turquoise , teal , and grue . The web color cyan shown at right

370-462: A dark brown. From the Renaissance onward, painters used this system to create their colours (see RYB colour model ). The RYB model was used for colour printing by Jacob Christoph Le Blon as early as 1725. Later, printers discovered that more accurate colours could be created by using combinations of cyan, magenta, yellow, and black ink, put onto separate inked plates and then overlaid one at

444-480: A deep blue colour, was once employed in medieval years, but it is unstable pigment, losing its colour especially under dry conditions. Lapis lazuli , mined in Afghanistan for more than three thousand years, was used for jewelry and ornaments, and later was crushed and powdered and used as a pigment. The more it was ground, the lighter the blue colour became. Natural ultramarine , made by grinding lapis lazuli into

518-705: A fine powder, was the finest available blue pigment in the Middle Ages and the Renaissance . It was extremely expensive, and in Italian Renaissance art, it was often reserved for the robes of the Virgin Mary . Intense efforts have focused on blue flowers and the possibility that natural blue colourants could be used as food dyes. Commonly, blue colours in plants are anthocyanins : "the largest group of water-soluble pigments found widespread in

592-429: A highly regarded precious gem. Turquoise comes in a variety of shades from green to blue, but cyan hues are particularly prevalent. Approximately 3,700 years ago, an intricately crafted dragon-shaped treasure made from over 2,000 pieces of turquoise and jade was created. This artifact is widely recognized as the oldest Chinese dragon totem by many Chinese scholars. Turquoise jewelry also held significant importance among

666-420: A lower frequency and a longer wavelength gradually appear more green. Purer blues are in the middle of this range, e.g., around 470 nanometres. Isaac Newton included blue as one of the seven colours in his first description of the visible spectrum . He chose seven colours because that was the number of notes in the musical scale, which he believed was related to the optical spectrum. He included indigo ,

740-463: A more complete list see the List of colours ). In nature, many blue phenomena arise from structural colouration , the result of interference between reflections from two or more surfaces of thin films , combined with refraction as light enters and exits such films. The geometry then determines that at certain angles, the light reflected from both surfaces interferes constructively, while at other angles,

814-494: A printed page. To reproduce the web color cyan in inks, it is necessary to add some white ink to the printer's cyan below, so when it is reproduced in printing, it is not a primary subtractive color. It is called aqua (a name in use since 1598) because it is a color commonly associated with water , such as the appearance of the water at a tropical beach. Cyan is also one of the common inks used in four-color printing , along with magenta , yellow , and black ; this set of colors

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888-468: A quick-drying binding agent, such as egg yolk ( tempera painting ); or with a slow-drying oil, such as linseed oil , for oil painting . Two inorganic but synthetic blue pigments are cerulean blue (primarily cobalt(II) stanate: Co 2 SnO 4 ) and Prussian blue (milori blue: primarily Fe 7 (CN) 18 ). The chromophore in blue glass and glazes is cobalt (II). Diverse cobalt(II) salts such as cobalt carbonate or cobalt(II) aluminate are mixed with

962-475: A time onto paper. This method could produce almost all the colours in the spectrum with reasonable accuracy. On the HSV colour wheel , the complement of blue is yellow ; that is, a colour corresponding to an equal mixture of red and green light. On a colour wheel based on traditional colour theory ( RYB ) where blue was considered a primary colour, its complementary colour is considered to be orange (based on

1036-457: A tint being a cyan mixed with white, and a shade being mixed with black. Color nomenclature is subjective. Many shades of cyan with a bluish hue are called blue. Similarly, those with a greenish hue are referred to as green. A cyan with a dark shade is commonly known as teal . A teal blue shade leans toward the blue end of the spectrum. Variations of teal with a greener tint are commonly referred to as teal green . Turquoise , reminiscent of

1110-561: Is a secondary color in the RGB color model , which uses combinations of red, green and blue light to create all the colors on computer and television displays. In X11 colors , this color is called both cyan and aqua . In the HTML color list, this same color is called aqua. The web colors are more vivid than the cyan used in the CMYK color system, and the web colors cannot be accurately reproduced on

1184-432: Is classified as an industrial gas and is widely used for industrial and medical purposes. Liquid oxygen is obtained from the oxygen found naturally in air by fractional distillation in a cryogenic air separation plant . Air forces have long recognized the strategic importance of liquid oxygen, both as an oxidizer and as a supply of gaseous oxygen for breathing in hospitals and high-altitude aircraft flights. In 1985,

1258-481: Is no single word for blue, but rather different words for light blue ( голубой , goluboj ; Celeste ) and dark blue ( синий , sinij ; Azul ) (see Colour term ). Several languages, including Japanese and Lakota Sioux , use the same word to describe blue and green. For example, in Vietnamese , the colour of both tree leaves and the sky is xanh . In Japanese, the word for blue ( 青 , ao )

1332-399: Is now the blue of blue jeans. As the pace of organic chemistry accelerated, a succession of synthetic blue dyes were discovered including Indanthrone blue , which had even greater resistance to fading during washing or in the sun, and copper phthalocyanine . Woad and true indigo were once used but since the early 1900s, all indigo is synthetic. Produced on an industrial scale, indigo

1406-602: Is often used for colours that English speakers would refer to as green, such as the colour of a traffic signal meaning "go". In Lakota, the word tȟó is used for both blue and green, the two colours not being distinguished in older Lakota (for more on this subject, see Blue–green distinction in language ). Linguistic research indicates that languages do not begin by having a word for the colour blue. Colour names often developed individually in natural languages, typically beginning with black and white (or dark and light), and then adding red , and only much later – usually as

1480-494: Is one such commonly used pigment. A typical formulation of process cyan is shown in the color box on the right. Blue Blue is one of the three primary colours in the RYB colour model (traditional colour theory), as well as in the RGB (additive) colour model . It lies between violet and cyan on the spectrum of visible light . The term blue generally describes colours perceived by humans observing light with

1554-461: Is referred to as CMYK. In printing, the cyan ink is sometimes known as printer's cyan, process cyan, or process blue. While both the additive secondary and the subtractive primary are called cyan , they can be substantially different from one another. Cyan printing ink is typically more saturated than the RGB secondary cyan, depending on what RGB color space and ink are considered. That is, process cyan

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1628-568: Is the blue chromophore in stained glass windows , such as those in Gothic cathedrals and in Chinese porcelain beginning in the Tang dynasty . Copper(II) (Cu ) also produces many blue compounds, including the commercial algicide copper(II) sulfate (CuSO 4 5H 2 O). Similarly, vanadyl salts and solutions are often blue, e.g. vanadyl sulfate . When sunlight passes through the atmosphere,

1702-646: Is the blue of blue jeans. Blue dyes are organic compounds, both synthetic and natural. For food, the triarylmethane dye Brilliant blue FCF is used for candies. The search continues for stable, natural blue dyes suitable for the food industry. Various raspberry -flavoured foods are dyed blue. This was done to distinguish strawberry , watermelon and raspberry -flavoured foods. The company ICEE used Blue No. 1 for their blue raspberry ICEEs. Blue pigments were once produced from minerals, especially lapis lazuli and its close relative ultramarine . These minerals were crushed, ground into powder, and then mixed with

1776-409: Is the color between blue and green on the visible spectrum of light . It is evoked by light with a predominant wavelength between 500 and 520 nm , between the wavelengths of green and blue. In the subtractive color system, or CMYK color model , which can be overlaid to produce all colors in paint and color printing, cyan is one of the primary colors , along with magenta and yellow . In

1850-686: Is the colour of light between violet and cyan on the visible spectrum . Hues of blue include indigo and ultramarine , closer to violet; pure blue, without any mixture of other colours; Azure, which is a lighter shade of blue, similar to the colour of the sky; Cyan, which is midway in the spectrum between blue and green , and the other blue-greens such as turquoise , teal , and aquamarine . Blue also varies in shade or tint; darker shades of blue contain black or grey, while lighter tints contain white. Darker shades of blue include ultramarine, cobalt blue , navy blue , and Prussian blue ; while lighter tints include sky blue , azure , and Egyptian blue (for

1924-647: Is used in some commercial and military aircraft as a transportable source of breathing oxygen. Because of its cryogenic nature, liquid oxygen can cause the materials it touches to become extremely brittle. Liquid oxygen is also a very powerful oxidizing agent: organic materials will burn rapidly and energetically in liquid oxygen. Further, if soaked in liquid oxygen , some materials such as coal briquettes, carbon black , etc., can detonate unpredictably from sources of ignition such as flames, sparks or impact from light blows. Petrochemicals , including asphalt , often exhibit this behavior. The tetraoxygen molecule (O 4 )

1998-506: Is usually outside the RGB gamut , and there is no fixed conversion from CMYK primaries to RGB. Different formulations are used for printer's ink, so there can be variations in the printed color that is pure cyan ink. This is because real-world subtractive (unlike additive) color mixing does not consistently produce the same result when mixing apparently identical colors, since the specific frequencies filtered out to produce that color affect how it interacts with other colors. Phthalocyanine blue

2072-588: The Aztecs , who often featured this precious gemstone in vibrant frescoes for both symbolic and decorative purposes. The Aztecs revered turquoise, associating its color with the heavens and sacredness. Additionally, ancient Egyptians interpreted cyan hues as representing faith and truth, while Tibetans viewed them as a symbol of infinity. After earlier uses in various contexts, cyan hues found increased use in diverse cultures due to their appealing aesthetic qualities in religious structures and art pieces. For example,

2146-614: The Baltic Sea area and Northern Europe , and are also found in Eastern , Central , and Southern Europe . Blue eyes are also found in parts of Western Asia , most notably in Afghanistan , Syria , Iraq , and Iran . In Estonia , 99% of people have blue eyes. In Denmark in 1978, only 8% of the population had brown eyes, though through immigration, today that number is about 11%. In Germany , about 75% have blue eyes. In

2220-573: The Caucasus , and as far away as Mauritania . It was used in the funeral mask of Tutankhamun (1341–1323 BC). A term for Blue was relatively rare in many forms of ancient art and decoration, and even in ancient literature. The Ancient Greek poets described the sea as green, brown or "the colour of wine". The colour is mentioned several times in the Hebrew Bible as ' tekhelet '. Reds, blacks, browns, and ochres are found in cave paintings from

2294-470: The Munsell colour wheel ). In 1993, high-brightness blue LEDs were demonstrated by Shuji Nakamura of Nichia Corporation . In parallel, Isamu Akasaki and Hiroshi Amano of Nagoya University were working on a new development which revolutionized LED lighting. Nakamura was awarded the 2006 Millennium Technology Prize for his invention. Nakamura, Hiroshi Amano and Isamu Akasaki were awarded

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2368-833: The Nobel Prize in Physics in 2014 for the invention of an efficient blue LED. Lasers emitting in the blue region of the spectrum became widely available to the public in 2010 with the release of inexpensive high-powered 445–447 nm laser diode technology. Previously the blue wavelengths were accessible only through DPSS which are comparatively expensive and inefficient, but still widely used by scientists for applications including optogenetics , Raman spectroscopy , and particle image velocimetry , due to their superior beam quality. Blue gas lasers are also still commonly used for holography , DNA sequencing , optical pumping , among other scientific and medical applications. Blue

2442-539: The Tyndall scattering of light in the stroma, an optical effect similar to what accounts for the blueness of the sky. The irises of the eyes of people with blue eyes contain less dark melanin than those of people with brown eyes, which means that they absorb less short-wavelength blue light, which is instead reflected out to the viewer. Eye colour also varies depending on the lighting conditions, especially for lighter-coloured eyes. Blue eyes are most common in Ireland,

2516-629: The additive color system, or RGB color model , used to create all the colors on a computer or television display, cyan is made by mixing equal amounts of green and blue light . Cyan is the complement of red ; it can be made by the removal of red from white. Mixing red light and cyan light at the right intensity will make white light. Different shades of cyan can vary in terms of hue, chroma (also known as saturation, intensity, or colorfulness), or lightness (or value, tone, or brightness), or any combination of these characteristics. Differences in value can also be referred to as tints and shades, with

2590-532: The imagination , cold , and sadness . The modern English word blue comes from Middle English bleu or blewe , from the Old French bleu , a word of Germanic origin, related to the Old High German word blao (meaning 'shimmering, lustrous'). In heraldry , the word azure is used for blue . In Russian , Spanish, Mongolian , Irish , and some other languages, there

2664-402: The iridophore cells in some fish and frogs. Blue eyes do not actually contain any blue pigment. Eye colour is determined by two factors: the pigmentation of the eye's iris and the scattering of light by the turbid medium in the stroma of the iris . In humans, the pigmentation of the iris varies from light brown to black. The appearance of blue, green, and hazel eyes results from

2738-425: The mandarin fish and the picturesque dragonet . More commonly, blueness in animals is a structural colouration ; an optical interference effect induced by organized nanometre-sized scales or fibres. Examples include the plumage of several birds like the blue jay and indigo bunting , the scales of butterflies like the morpho butterfly , collagen fibres in the skin of some species of monkey and opossum , and

2812-790: The Islamic world, blue was the colour worn by Christians and Jews, because only Muslims were allowed to wear white and green. In the art and life of Europe during the early Middle Ages , blue played a minor role. This changed dramatically between 1130 and 1140 in Paris, when the Abbe Suger rebuilt the Saint Denis Basilica . Suger considered that light was the visible manifestation of the Holy Spirit. He installed stained glass windows coloured with cobalt , which, combined with

2886-655: The Romans, blue was the colour of mourning, as well as the colour of barbarians. The Celts and Germans reportedly dyed their faces blue to frighten their enemies, and tinted their hair blue when they grew old. The Romans made extensive use of indigo and Egyptian blue pigment, as evidenced, in part, by frescos in Pompeii . The Romans had many words for varieties of blue, including caeruleus , caesius , glaucus , cyaneus , lividus , venetus , aerius , and ferreus , but two words, both of foreign origin, became

2960-470: The USAF started a program of building its own oxygen-generation facilities at all major consumption bases. Liquid oxygen is the most common cryogenic liquid oxidizer propellant for spacecraft rocket applications, usually in combination with liquid hydrogen , kerosene or methane . Liquid oxygen was used in the first liquid fueled rocket . The World War II V-2 missile also used liquid oxygen under

3034-558: The United States and Europe, blue is the colour that both men and women are most likely to choose as their favourite, with at least one recent survey showing the same across several other countries, including China, Malaysia, and Indonesia. Past surveys in the US and Europe have found that blue is the colour most commonly associated with harmony , confidence , masculinity , knowledge , intelligence , calmness , distance , infinity ,

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3108-417: The United States, as of 2006, 1 out of every 6 people, or 16.6% of the total population, and 22.3% of the white population , have blue eyes, compared with about half of Americans born in 1900, and a third of Americans born in 1950. Blue eyes are becoming less common among American children . In the US, males are 3–5% more likely to have blue eyes than females. As early as the 7th millennium BC , lapis lazuli

3182-722: The Upper Paleolithic period, but not blue. Blue was also not used for dyeing fabric until long after red, ochre, pink, and purple. This is probably due to the perennial difficulty of making blue dyes and pigments. On the other hand, the rarity of blue pigment made it even more valuable. The earliest known blue dyes were made from plants – woad in Europe, indigo in Asia and Africa, while blue pigments were made from minerals, usually either lapis lazuli or azurite , and required more. Blue glazes posed still another challenge since

3256-418: The blue wavelengths are scattered more widely by the oxygen and nitrogen molecules, and more blue comes to our eyes. This effect is called Rayleigh scattering , after Lord Rayleigh and confirmed by Albert Einstein in 1911. The sea is seen as blue for largely the same reason: the water absorbs the longer wavelengths of red and reflects and scatters the blue, which comes to the eye of the viewer. The deeper

3330-741: The color of the stone. In the 1870s, the French sculptor Frédéric Bartholdi began the construction of what would later become the Statue of Liberty . Over time, exposure to the elements caused the copper structure to develop its distinctive patina , now recognized as iconic cyan. Following this, there was a significant advancement in the use of cyan during the late 19th and early 20th centuries. Impressionist artists, such as Claude Monet in his renowned Water Lilies , effectively incorporated cyan hues into their works. Deviating from traditional interpretations of local color under neutral lighting conditions,

3404-463: The early blue dyes and pigments were not thermally robust. In c.  2500 BC , the blue glaze Egyptian blue was introduced for ceramics, as well as many other objects. The Greeks imported indigo dye from India, calling it indikon, and they painted with Egyptian blue. Blue was not one of the four primary colours for Greek painting described by Pliny the Elder (red, yellow, black, and white). For

3478-413: The focus of artists was on accurately depicting perceived color and the influence of light on altering object hues. Specifically, daylight plays a significant role in shifting the perceived color of objects toward cyan hues. In 1917, the color term teal was introduced to describe deeper shades of cyan. In the late 19th century, while traditional nomenclature of red , yellow , and blue persisted,

3552-496: The formula of his colour. In 1828, another scientist, Christian Gmelin then a professor of chemistry in Tübingen, found the process and published his formula. This was the beginning of new industry to manufacture artificial ultramarine, which eventually almost completely replaced the natural product. In 1878 German chemists synthesized indigo . This product rapidly replaced natural indigo, wiping out vast farms growing indigo. It

3626-453: The genus Nessaea , where blue is created by pterobilin . Other blue pigments of animal origin include phorcabilin, used by other butterflies in Graphium and Papilio (specifically P. phorcas and P. weiskei ), and sarpedobilin, which is used by Graphium sarpedon . Blue-pigmented organelles , known as "cyanosomes", exist in the chromatophores of at least two fish species,

3700-424: The hue between blue and violet, as one of the separate colours, though today it is usually considered a hue of blue. In painting and traditional colour theory , blue is one of the three primary colours of pigments (red, yellow, blue), which can be mixed to form a wide gamut of colours. Red and blue mixed together form violet, blue and yellow together form green. Mixing all three primary colours together produces

3774-514: The hues evolved, the printing industry maintained the use of the traditional terms red , yellow , and blue . Consequently, pinpointing the exact date of origin for CMYK , in which cyan serves as a primary color, proves challenging . In August 1991, the HP Deskwriter 500C became the first Deskwriter to offer color printing as an option. It used interchangeable black and color (cyan, magenta, and yellow) inkjet print cartridges. With

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3848-501: The inclusion of cyan ink in printers, the term "cyan" has become widely recognized in both home and office settings. According to TUP/Technology User Profile 2020, approximately 70% of online American adults regularly use a home printer. Its name is derived from the Ancient Greek word kyanos (κύανος), meaning "dark blue enamel, Lapis lazuli ". It was formerly known as "cyan blue" or cyan-blue, and its first recorded use as

3922-445: The last main category of colour accepted in a language – adding the colour blue, probably when blue pigments could be manufactured reliably in the culture using that language. The term blue generally describes colours perceived by humans observing light with a dominant wavelength between approximately 450 and 495 nanometres. Blues with a higher frequency and thus a shorter wavelength gradually look more violet, while those with

3996-632: The light from the red glass, filled the church with a bluish violet light. The church became the marvel of the Christian world , and the colour became known as the "bleu de Saint-Denis" . In the years that followed even more elegant blue stained glass windows were installed in other churches, including at Chartres Cathedral and Sainte-Chapelle in Paris. In the 12th century the Roman Catholic Church dictated that painters in Italy (and

4070-516: The light interferes destructively. Diverse colours therefore appear despite the absence of colourants. Egyptian blue , the first artificial pigment, was produced in the third millennium BC in Ancient Egypt. It is produced by heating pulverized sand, copper, and natron . It was used in tomb paintings and funereal objects to protect the dead in their afterlife. Prior to the 1700s, blue colourants for artwork were mainly based on lapis lazuli and

4144-456: The manufacture of wallpaper, and in the 19th century was widely used by French impressionist painters. Beginning in the 1820s, Prussian blue was imported into Japan through the port of Nagasaki . It was called bero-ai , or Berlin blue, and it became popular because it did not fade like traditional Japanese blue pigment, ai-gami , made from the dayflower . Prussian blue was used by both Hokusai , in his wave paintings, and Hiroshige . In 1799

4218-417: The more blue it often appears to the eye. For example, mountains in the distance often appear blue. This is the effect of atmospheric perspective ; the farther an object is away from the viewer, the less contrast there is between the object and its background colour, which is usually blue. In a painting where different parts of the composition are blue, green and red, the blue will appear to be more distant, and

4292-745: The most enduring; blavus , from the Germanic word blau , which eventually became bleu or blue; and azureus , from the Arabic word lazaward , which became azure. Blue was widely used in the decoration of churches in the Byzantine Empire. By contrast, in the Islamic world, blue was of secondary to green, believed to be the favourite colour of the Prophet Mohammed . At certain times in Moorish Spain and other parts of

4366-687: The name A-Stoff and Sauerstoff . In the 1950s, during the Cold War both the United States' Redstone and Atlas rockets, and the Soviet R-7 Semyorka used liquid oxygen. Later, in the 1960s and 1970s, the ascent stages of the Apollo Saturn rockets , and the Space Shuttle main engines used liquid oxygen. As of 2024, many active rockets use liquid oxygen: Cyan Cyan ( / ˈ s aɪ . ə n , - æ n / )

4440-439: The nitrogen has evaporated from such a vessel, there is a risk that liquid oxygen remaining can react violently with organic material. Conversely, liquid nitrogen or liquid air can be oxygen-enriched by letting it stand in open air; atmospheric oxygen dissolves in it, while nitrogen evaporates preferentially. The surface tension of liquid oxygen at its normal pressure boiling point is 13.2 dyn/cm. In commerce, liquid oxygen

4514-427: The observer goes, the darker the blue becomes. In the open sea, only about 1% of light penetrates to a depth of 200 metres (see underwater and euphotic depth ). The colour of the sea is also affected by the colour of the sky, reflected by particles in the water; and by algae and plant life in the water, which can make it look green; or by sediment, which can make it look brown. The farther away an object is,

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4588-502: The plant kingdom". In the few plants that exploit structural colouration, brilliant colours are produced by structures within cells. The most brilliant blue colouration known in any living tissue is found in the marble berries of Pollia condensata , where a spiral structure of cellulose fibrils scattering blue light. The fruit of quandong ( Santalum acuminatum ) can appear blue owing to the same effect. Blue-pigmented animals are relatively rare. Examples of which include butterflies of

4662-496: The printing industry initiated a shift towards utilizing magenta and cyan inks for red and blue hues, respectively. This transition aimed to establish a more versatile color gamut achievable with only three primary colors. In 1949, a document in the printing industry stated: “The four-color set comprises Yellow , Red (magenta) , Blue (cyan) , Black ”. This practice of labeling magenta , yellow , and cyan as red , yellow , and blue persisted until 1961. As

4736-572: The prominent dome of the Goharshad Mosque in Iran , built in 1418, showcases this trend. Additionally, Jacopo da Pontormo's use of a teal shade for Mary's robe in the 1528 painting Carmignano Visitation demonstrates the allure for these hues. During the 16th century, speakers of the English language began using the term turquoise to describe the cyan color of objects that resembled

4810-430: The red closer to the viewer. The cooler a colour is, the more distant it seems. Blue light is scattered more than other wavelengths by the gases in the atmosphere , hence our "blue planet". Some of the most desirable gems are blue, including sapphire and tanzanite . Compounds of copper(II) are characteristically blue and so are many copper-containing minerals. Azurite ( Cu 3 (CO 3 ) 2 (OH) 2 ) , with

4884-423: The related mineral ultramarine. A breakthrough occurred in 1709 when German druggist and pigment maker Johann Jacob Diesbach discovered Prussian blue . The new blue arose from experiments involving heating dried blood with iron sulphides and was initially called Berliner Blau. By 1710 it was being used by the French painter Antoine Watteau , and later his successor Nicolas Lancret . It became immensely popular for

4958-524: The rest of Europe consequently) to paint the Virgin Mary with blue, which became associated with holiness, humility and virtue. In medieval paintings, blue was used to attract the attention of the viewer to the Virgin Mary. Paintings of the mythical King Arthur began to show him dressed in blue. The coat of arms of the kings of France became an azure or light blue shield, sprinkled with golden fleur-de-lis or lilies. Blue had come from obscurity to become

5032-400: The royal colour. Blue came into wider use beginning in the Renaissance, when artists began to paint the world with perspective, depth, shadows, and light from a single source. In Renaissance paintings, artists tried to create harmonies between blue and red, lightening the blue with lead white paint and adding shadows and highlights. Raphael was a master of this technique, carefully balancing

5106-460: The silica prior to firing. The cobalt occupies sites otherwise filled with silicon. Methyl blue is the dominant blue pigment in inks used in pens. Blueprinting involves the production of Prussian blue in situ. Certain metal ions characteristically form blue solutions or blue salts. Of some practical importance, cobalt is used to make the deep blue glazes and glasses. It substitutes for silicon or aluminum ions in these materials. Cobalt

5180-434: The stone with the same name, is a shade in the green spectrum of cyan hues. Celeste is a lightly tinted cyan that represents the color of a clear sky. Other colors in the cyan color range are electric blue , aquamarine , and others described as blue-green . Cyan boasts a rich and diverse history, holding cultural significance for millennia. In ancient civilizations, turquoise , valued for its aesthetic appeal, served as

5254-526: Was first predicted in 1924 by Gilbert N. Lewis , who proposed it to explain why liquid oxygen defied Curie's law . Modern computer simulations indicate that, although there are no stable O 4 molecules in liquid oxygen, O 2 molecules do tend to associate in pairs with antiparallel spins , forming transient O 4 units. Liquid nitrogen has a lower boiling point at −196 °C (77 K) than oxygen's −183 °C (90 K), and vessels containing liquid nitrogen can condense oxygen from air: when most of

5328-707: Was mined in the Sar-i Sang mines, in Shortugai , and in other mines in Badakhshan province in northeast Afghanistan . Lapis lazuli artifacts, dated to 7570 BC, have been found at Bhirrana , which is the oldest site of Indus Valley civilisation . Lapis was highly valued by the Indus Valley Civilisation (7570–1900 BC). Lapis beads have been found at Neolithic burials in Mehrgarh ,

5402-547: Was replaced by the finer indigo from America. In the 19th century, synthetic blue dyes and pigments gradually replaced organic dyes and mineral pigments. Dark blue became a common colour for military uniforms and later, in the late 20th century, for business suits. Because blue has commonly been associated with harmony, it was chosen as the colour of the flags of the United Nations and the European Union . In

5476-467: Was used in ancient Egypt for jewellery and ornament and later, in the Renaissance , to make the pigment ultramarine , the most expensive of all pigments. In the eighth century Chinese artists used cobalt blue to colour fine blue and white porcelain . In the Middle Ages , European artists used it in the windows of cathedrals . Europeans wore clothing coloured with the vegetable dye woad until it

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