Orpiment is a deep-colored, orange-yellow

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 ...

sulfide mineral The sulfide minerals are a class of minerals containing sulfide (S2−) or disulfide (S22−) as the major anion. Some sulfide minerals are economically important as metal ores. The sulfide class also includes the selenides, the tellurides, the ...

with formula . It is found in volcanic

fumarole A fumarole (or fumerole) is a vent in the surface of the Earth or other rocky planet from which hot volcanic gases and vapors are emitted, without any accompanying liquids or solids. Fumaroles are characteristic of the late stages of volcani ...

s, low-temperature

hydrothermal Hydrothermal circulation in its most general sense is the circulation of hot water (Ancient Greek ὕδωρ, ''water'',Liddell, H.G. & Scott, R. (1940). ''A Greek-English Lexicon. revised and augmented throughout by Sir Henry Stuart Jones. with th ...

veins, and

hot spring A hot spring, hydrothermal spring, or geothermal spring is a spring produced by the emergence of geothermally heated groundwater onto the surface of the Earth. The groundwater is heated either by shallow bodies of magma (molten rock) or by circ ...

s and is formed both by sublimation and as a byproduct of the decay of another arsenic sulfide mineral,

realgar Realgar ( ), also known as "ruby sulphur" or "ruby of arsenic", is an arsenic sulfide mineral with the chemical formula α-. It is a soft, sectile mineral occurring in monoclinic crystals, or in granular, compact, or powdery form, often in asso ...

. Orpiment takes its name from the Latin ''auripigmentum'' (''aurum'', "gold" + ''pigmentum'', "

pigment A pigment is a colored material that is completely or nearly insoluble in water. In contrast, dyes are typically soluble, at least at some stage in their use. Generally dyes are often organic compounds whereas pigments are often inorganic compo ...

") because of its deep-yellow color.

Historical uses

Orpiment was traded in the

Roman Empire The Roman Empire ( la, Imperium Romanum ; grc-gre, Βασιλεία τῶν Ῥωμαίων, Basileía tôn Rhōmaíōn) was the post-Republican period of ancient Rome. As a polity, it included large territorial holdings around the Mediterr ...

and was used as a medicine in

China China, officially the People's Republic of China (PRC), is a country in East Asia. It is the world's most populous country, with a population exceeding 1.4 billion, slightly ahead of India. China spans the equivalent of five time zones and ...

, even though it is very toxic. It has been used as fly poison and to tip arrows with poison. Because of its striking color, it was of interest to

alchemists Alchemy (from Arabic: ''al-kīmiyā''; from Ancient Greek: χυμεία, ''khumeía'') is an ancient branch of natural philosophy, a philosophical and protoscientific tradition that was historically practiced in China, India, the Muslim world, ...

, both in China and the West, searching for a way to make gold. It also has been found in the wall decorations of

Tutankhamun Tutankhamun (, egy, twt-ꜥnḫ-jmn), Egyptological pronunciation Tutankhamen () (), sometimes referred to as King Tut, was an Egyptian pharaoh who was the last of his royal family to rule during the end of the Eighteenth Dynasty (ruled ...

's tomb and ancient Egyptian scrolls, and on the walls of the

Taj Mahal The Taj Mahal (; ) is an Islamic ivory-white marble mausoleum on the right bank of the river Yamuna in the Indian city of Agra. It was commissioned in 1631 by the Mughal emperor Shah Jahan () to house the tomb of his favourite wife, Mu ...

. For centuries, orpiment was ground down and used as a pigment in painting and for

sealing wax Sealing wax is a wax material of a seal which, after melting, hardens quickly (to paper, parchment, ribbons and wire, and other material) forming a bond that is difficult to separate without noticeable tampering. Wax is used to verify something su ...

, and was even used in ancient China as a

correction fluid A correction fluid is an opaque, usually white fluid applied to paper to mask errors in text. Once dried, it can be handwritten or typed upon. It is typically packaged in small bottles, lids attached to brushes (or triangular pieces of foam) th ...

. It was one of the few clear, bright-yellow pigments available to artists until the 19th century. However, its extreme toxicity and incompatibility with other common pigments, including

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 cu ...

and

copper Copper is a chemical element with the symbol Cu (from la, cuprum) and atomic number 29. It is a soft, malleable, and ductile metal with very high thermal and electrical conductivity. A freshly exposed surface of pure copper has a pinkis ...

-based substances such as

verdigris Verdigris is the common name for blue-green, copper-based pigments that form a patina on copper, bronze, and brass. The technical literature is ambiguous as to its chemical composition. Some sources refer to "neutral verdigris" as copper(II) ac ...

and

azurite Azurite is a soft, deep-blue copper mineral produced by weathering of copper ore deposits. During the early 19th century, it was also known as chessylite, after the Type locality (geology), type locality at Chessy, Rhône, Chessy-les-Mines near ...

, meant that its use as a pigment ended when cadmium yellows, chromium yellows and organic dye-based colors were introduced during the 19th century. Orpiment is mentioned in the 17th century by

Robert Hooke Robert Hooke FRS (; 18 July 16353 March 1703) was an English polymath active as a scientist, natural philosopher and architect, who is credited to be one of two scientists to discover microorganisms in 1665 using a compound microscope that ...

in ''

Micrographia ''Micrographia: or Some Physiological Descriptions of Minute Bodies Made by Magnifying Glasses. With Observations and Inquiries Thereupon.'' is a historically significant book by Robert Hooke about his observations through various lenses. It w ...

'' for the manufacture of small

shot Shot may refer to: Arts, entertainment, and media * ''Shot'' (album), by The Jesus Lizard *''Shot, Illusion, New God'', an EP by Gruntruck *'' Shot Rev 2.0'', a video album by The Sisters of Mercy * "Shot" (song), by The Rasmus * ''Shot'' (2017 f ...

. Scientists like

Richard Adolf Zsigmondy Richard Adolf Zsigmondy ( hu, Zsigmondy Richárd Adolf; 1 April 1865 – 23 September 1929) was an Austrian-born chemist. He was known for his research in colloids, for which he was awarded the Nobel Prize in chemistry in 1925, as well as for c ...

and Hermann Ambronn puzzled jointly over orpiment glass as early as 1904.

Contemporary uses

Orpiment is used in the production of

infrared Infrared (IR), sometimes called infrared light, is electromagnetic radiation (EMR) with wavelengths longer than those of visible light. It is therefore invisible to the human eye. IR is generally understood to encompass wavelengths from around ...

-transmitting glass, oil cloth,

linoleum Linoleum, sometimes shortened to lino, is a floor covering made from materials such as solidified linseed oil (linoxyn), Pine Resin, pine resin, ground Cork (material), cork dust, sawdust, and mineral fillers such as calcium carbonate, most com ...

semiconductor A semiconductor is a material which has an electrical resistivity and conductivity, electrical conductivity value falling between that of a electrical conductor, conductor, such as copper, and an insulator (electricity), insulator, such as glas ...

photoconductor Photoconductivity is an optical and electrical phenomenon in which a material becomes more electrically conductive due to the absorption of electromagnetic radiation such as visible light, ultraviolet light, infrared light, or gamma radiation. W ...

s, pigments, and

fireworks Fireworks are a class of Explosive, low explosive Pyrotechnics, pyrotechnic devices used for aesthetic and entertainment purposes. They are most commonly used in fireworks displays (also called a fireworks show or pyrotechnics), combining a l ...

. Mixed with two parts of

slaked lime Calcium hydroxide (traditionally called slaked lime) is an inorganic compound with the chemical formula Ca( OH)2. It is a colorless crystal or white powder and is produced when quicklime (calcium oxide) is mixed or slaked with water. It has ma ...

(calcium hydroxide), orpiment is still commonly used in rural India as a

depilatory Hair removal, also known as epilation or depilation, is the deliberate removal of body hair or head hair. Hair typically grows all over the human body and can vary in thickness and length across human populations. Hair can become more visible d ...

. It is used in the

tanning Tanning may refer to: *Tanning (leather), treating animal skins to produce leather *Sun tanning, using the sun to darken pale skin **Indoor tanning, the use of artificial light in place of the sun **Sunless tanning, application of a stain or dye t ...

industry to remove hair from hides.

Physical and optical properties

Orpiment is a common

monoclinic In crystallography, the monoclinic crystal system is one of the seven crystal systems. A crystal system is described by three vectors. In the monoclinic system, the crystal is described by vectors of unequal lengths, as in the orthorhombic s ...

arsenic sulfide mineral. It has a

Mohs hardness The Mohs scale of mineral hardness () is a qualitative ordinal scale, from 1 to 10, characterizing scratch resistance of various minerals through the ability of harder material to scratch softer material. The scale was introduced in 1812 by th ...

of 1.5 to 2 and a

specific gravity Relative density, or specific gravity, is the ratio of the density (mass of a unit volume) of a substance to the density of a given reference material. Specific gravity for liquids is nearly always measured with respect to water (molecule), wa ...

of 3.49. It melts at to . Optically, it is biaxial (−) with

refractive indices In optics, the refractive index (or refraction index) of an optical medium is a dimensionless number that gives the indication of the light bending ability of that medium. The refractive index determines how much the path of light is bent, or ...

of ''a'' = 2.4, ''b'' = 2.81, ''g'' = 3.02.

Crystal structure

File:Orpiment-unit-cell-3D-balls.png, File:Orpiment-layer-3D-balls.png, File:Orpiment-layers-stacking-3D-balls.png,

Gallery of orpiment specimens

File:Orpiment.ვკ.jpg, Orpiment from

Racha Racha (also Račha, , ''Račʼa'') is a highland area in western Georgia, located in the upper Rioni river valley and hemmed in by the Greater Caucasus mountains. Under Georgia's current subdivision, Racha is included in the Racha-Lechkhumi and ...

, northern

Georgia Georgia most commonly refers to: * Georgia (country), a country in the Caucasus region of Eurasia * Georgia (U.S. state), a state in the Southeast United States Georgia may also refer to: Places Historical states and entities * Related to the ...

region File:Orpiment-Realgar-Quartz-154641.jpg, Orpiment and

on a vuggy, quartz matrix, Nishinomaki Mine,

Gunma Prefecture is a prefecture of Japan located in the Kantō region of Honshu. Gunma Prefecture has a population of 1,937,626 (1 October 2019) and has a geographic area of 6,362 km2 (2,456 sq mi). Gunma Prefecture borders Niigata Prefecture and Fukushima ...

, Japan File:MFN MIN 1977 0028 Auripigment.jpg, Orpiment from La Libertad, Quiruvilca, Peru File:Orpiment-d06-185b.jpg, El'brusskiy arsenic mine,

Kabardino-Balkarian Republic The Kabardino-Balkarian Republic (russian: Кабарди́но-Балка́рская Респу́блика, ''Kabardino-Balkarskaya Respublika''; kbd, Къэбэрдей-Балъкъэр Республикэ, ''Ķêbêrdej-Baĺķêr Respublik� ...

, Northern Caucasus Region, Russia

References

* ''The Merck Index: An Encyclopedia of Chemicals, Drugs, and Biologicals''. 11th Edition. Ed. Susan Budavari. Merck & Co., Inc., N.J., U.S.A. 1989. * William Mesny. ''Mesny’s Chinese Miscellany. A Text Book of Notes on China and the Chinese.'' Shanghai. Vol. III, (1899), p. 251; Vol. IV, (1905), pp. 26. * Fitzhugh, E.W., Orpiment and Realgar, in Artists’ Pigments, A Handbook of Their History and Characteristics, Vol 3: E.W. Fitzhugh (Ed.) Oxford University Press 1997, p. 47 – 80

External links

Webexhibits "Pigments Through the Ages: Orpiment"

Babylonian Talmud Tractate Chullin
see

Rashi Shlomo Yitzchaki ( he, רבי שלמה יצחקי; la, Salomon Isaacides; french: Salomon de Troyes, 22 February 1040 – 13 July 1105), today generally known by the acronym Rashi (see below), was a medieval French rabbi and author of a compre ...

'haZarnich'
Orpiment
Colourlex {{Commons category, Orpiment Arsenic minerals Sulfide minerals Inorganic pigments Alchemical substances Monoclinic minerals Minerals in space group 14