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Orpiment is a deep-colored, orange-yellow arsenic sulfide mineral with formula As
2S
3. It is found in volcanic fumaroles, low-temperature hydrothermal veins, and hot springs 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 edit
Orpiment was traded in the Roman Empire and was used as a medicine in China, even though it is very toxic. It has been used as fly poison[1] and to tip arrows with poison.[2] Because of its striking color, it was of interest to alchemists, both in China and the West, searching for a way to make gold. It also has been found in the wall decorations of Tutankhamun's tomb and ancient Egyptian scrolls, and on the walls of the Taj Mahal.[3]
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.[4] 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 and copper-based substances such as verdigris and azurite,[5][3] 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 in Micrographia for the manufacture of small shot.[6]
Scientists like Richard Adolf Zsigmondy and Hermann Ambronn puzzled jointly over the amorphous form of As
2S
3, "orpiment glass", as early as 1904.[7]
Contemporary uses edit
Orpiment is used in the production of infrared-transmitting glass, oil cloth, linoleum, semiconductors, photoconductors, pigments, and fireworks. 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 edit
Orpiment is a common monoclinic arsenic sulfide mineral. It has a Mohs hardness of 1.5 to 2 and a specific gravity of 3.49. It melts at 300 °C (570 °F) to 325 °C (620 °F). Optically, it is biaxial (−) with refractive indices of a = 2.4, b = 2.81, g = 3.02.
Crystal structure edit
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Orpiment's unit cell -
Orpiment's crystal structure consists of sheets -
The sheets are stacked into layers
Gallery of orpiment specimens edit
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Orpiment from La Libertad, Quiruvilca, Peru -
El'brusskiy arsenic mine, Kabardino-Balkarian Republic, Northern Caucasus Region, Russia
- ^ Miller, George (1826). Popular philosophy: or, The book of nature laid open upon Christian principles, by the ed. of The Cheap magazine.
- ^ Mesny, William (1899). Mesny's Chinese Miscellany. China Gazette Office.
- ^ a b St. Clair, Kassia (2016). The Secret Lives of Colour. London: John Murray. pp. 82–83. ISBN 9781473630819. OCLC 936144129.
- ^ "雌黄在古代充当"涂改液"". news.xinhuanet.com. Archived from the original on 6 August 2016. Retrieved 9 August 2022.
- ^ 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. 52
- ^ Hooke, Robert. "Micrographia". Project Gutenberg. Retrieved 24 October 2012.
- ^ "Richard Adolf Zsigmondy: Properties of Colloids". Nobel Lectures, Chemistry 1922-1941. Amsterdam: Elsevier Publishing Company. 1966.