Its name comes from the Arabic rahj al-ġār (رهج الغار[rahdʒælɣaːr]listenⓘ, "powder of the mine"), via Medieval Latin, and its earliest record in English is in the 1390s.[7][8][9]
Uses
Realgar is a minor ore of arsenic extracted in China, Peru, and the Philippines.[10]
Historical uses
Realgar was used by firework manufacturers to create the color white in fireworks prior to the availability of powdered metals such as aluminium, magnesium and titanium. It is still used in combination with potassium chlorate to make a contact explosive known as "red explosive" for some types of torpedoes and other novelty exploding fireworks branded as 'cracker balls', as well in the cores of some types of crackling stars.[citation needed]
Realgar was commonly used in leather manufacturing to remove hair from animal pelts. Because it is a known carcinogen and an arsenic poison, and because substitutes are available, it is rarely used today for this purpose.
The ancient Greeks, who called realgar σανδαράκη (sandarákē), understood that it was poisonous. From this, realgar has also historically been known in English as sandarac.
Realgar was also used by Ancient Greek apothecaries to make a medicine known as "bull's blood".[12] The Greek physician Nicander described a death by "bull's blood", which matches the known effects of arsenic poisoning.[12] Bull's blood is the poison that is said to have been used by Themistocles and Midas for suicide.[12]
The Chinese name for realgar is 雄黃 (Mandarinxiónghuáng), literally 'masculine yellow', as opposed to orpiment which is 'feminine yellow'.[13]
Realgar was, along with orpiment, traded in the Roman Empire and was used as a red paint pigment. Early occurrences of realgar as a red paint pigment are known for works of art from China, India, Central Asia, and Egypt. It was used in Venetian fine-art painting during the Renaissance era, though rarely elsewhere in Europe, a use which died out by the 18th century.[14] It was also used as medicine. Other traditional uses include manufacturing lead shot, printing, and dyeing calico cloth. It was used to poison rats in medieval Spain and in 16th century England.[15]
After a long period of exposure to light, realgar changes form to a yellow powder known as pararealgar (β-As4S4). It was once thought that this powder was the yellow sulfide orpiment, but is a distinct chemical compound.[16]
Gallery
The unit cell of realgar, showing clearly the As4S4 molecules it contains
Cluster of realgar crystals from Getchell Mine, Adam Peak, Potosi District, Humboldt County, Nevada, United States
Cherry-red realgar crystals atop a matrix, and a sharp acicular spray of the rare species picropharmacolite (white needles) below
Crystals of realgar, quartz, chalcopyrite and galena, from Quiruvilca Mine, La Libertad, Peru
^"Arsenic"(PDF). Mineral commodity summaries. United States Geological Survey. January 2021. Retrieved 28 February 2021.
^Realgar(PDF). N.J. Department of Environmental Protection (Report). Hazardous Substance Factsheet. State of New Jersey. April 2008.
^ abcArnould, Dominique (1993). "Boire le sang de taureau: La mort de Thémistocle" [Drinking bull's blood: The death of Themistocles]. Revue de philologie, de littérature et d'histoire anciennes (in French). LXVII (2): 229–235.
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. 425–426.
American Mineralogist Vol 80, pp 400–403, 1995 [1]
American Mineralogist Vol 20, pp 1266–1274, 1992 [2]
