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, b ...

sulfide mineral with formula . It is found in volcanic fumaroles, low-temperature hydrothermal 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. Orpiment takes its name from the Latin ''auripigmentum'' (''aurum'', "gold" + ''pigmentum'', " pigment") 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-Roman Republic, Republican period of ancient Rome. As a polity, it included large territorial holdings aro ...

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 List of countries and dependencies by population, most populous country, with a Population of China, population exceeding 1.4 billion, slig ...

, 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 ...

, 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, ...

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

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 pink ...

-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) ...

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 at Chessy-les-Mines near Lyon, France. The mineral, a basic car ...

, meant that its use as a pigment ended when

cadmium yellow Cadmium pigments are a class of pigments that contain cadmium. Most of the cadmium produced worldwide has been for use in rechargeable nickel–cadmium batteries, which have been replaced by other rechargeable nickel-chemistry cell varieties ...

s, chromium yellows and organic

dye A dye is a colored substance that chemically bonds to the substrate to which it is being applied. This distinguishes dyes from pigments which do not chemically bind to the material they color. Dye is generally applied in an aqueous solution and ...

-based colors were introduced during the 19th century. Orpiment is mentioned in the 17th century by Robert Hooke in '' Micrographia'' for the manufacture of small shot. Scientists like Richard Adolf Zsigmondy 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 Light, visible light. It is therefore invisible to the human eye. IR is generally understood to encompass wavelengths from ...

-transmitting glass,

oil cloth Oilcloth, also known as enameled cloth or American cloth, is close-woven cotton duck or linen cloth with a coating of boiled linseed oil to make it waterproof. Manufacture Boiled linseed oil was prepared by a long boiling of linseed oil with me ...

, linoleum,

semiconductor A semiconductor is a material which has an electrical conductivity value falling between that of a conductor, such as copper, and an insulator, such as glass. Its resistivity falls as its temperature rises; metals behave in the opposite way ...

s, photoconductors, pigments, and

fireworks Fireworks are a class of low explosive 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 large number of devices ...

. Mixed with two parts of slaked lime (calcium hydroxide), orpiment is still commonly used in rural India as a depilatory. It is used in the tanning 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 ...

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 ...

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 at its dens ...

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

, northern Georgia region File:Orpiment-Realgar-Quartz-154641.jpg, Orpiment and realgar 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 Fuku ...

, 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, 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