Orpiment: Difference between revisions

Orpiment
Orpiment
	Orpiment
General
Category	Sulfide mineral
Formula; (repeating unit)	As2S3
Strunz classification	02.FA.30
Crystal system	Monoclinic Prismatic
Space group	Monoclinic 2/m
Unit cell	a = 11.475(5) Å, b = 9.577(4) Å, c = 4.256(2) Å, β = 90.45(5)°; Z=4
Identification
Color	Lemon-yellow to golden or brownish yellow
Crystal habit	Commonly in foliated columnar or fibrous aggregates; may be reniform or botryoidal; also granular or powdery; rarely as prismatic crystals
Twinning	On {100}
Cleavage	Perfect on {010}, imperfect on {100};
Tenacity	Sectile
Mohs scale hardness	1.5 - 2
Luster	Resinous, pearly on cleavage surface
Streak	Pale lemon-yellow
Diaphaneity	Transparent
Specific gravity	3.49
Optical properties	Biaxial (-)
Refractive index	nα = 2.400 nβ = 2.810 nγ = 3.020
Birefringence	δ = 0.620
Pleochroism	In reflected light, strong, white to pale gray with reddish tint; in transmitted light, Y = yellow, Z = greenish yellow
2V angle	Measured: 30° to 76°, Calculated: 62°
Dispersion	r > v, strong
References

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Orpiment is a deep orange-yellow colored mineral, a form of arsenic sulphide that occurs worldwide. 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 mineral, realgar. It 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 and was used as a medicine in China even though it is very toxic. It has been used as a fly poison and to tip arrows with poison. Because of its striking color, it was of interest to alchemists, both in China and the West, searching for a way to make gold.

For centuries, orpiment was ground down and used as a pigment in painting and for sealing wax. 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, meant that its use as a pigment ended when cadmium yellows and dye-based colors were introduced during the 19th Century.

Orpiment is mentioned by Robert Hooke in Micrographia for the manufacture of small shot in the 17th century. Hooke transcribed an account by Sir Robert Moray to the Royal Society:

Take Lead out of the Pig what quantity you please, melt it down, stir and clear it with an iron Ladle, gathering together the blackish parts that swim at top like scum, and when you see the colour of the clear Lead to be greenish, but no sooner, strew upon it Auripigmentum powdered according to the quantity of Lead, about as much as will lye upon a half Crown piece will serve for eighteen or twenty pound weight of some sorts of Lead; others will require more, or less.^[4]

Auripigmentum here is the Latin for Orpiment.^[5]

Contemporary uses

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, orpiment is still commonly used in rural India as a depilatory. It is used in the tanning industry to remove hair from hides.

Technical Properties

Orpiment, As₂S₃, 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 to 325 °C. Optically it is biaxial (−) with refractive indices of a=2.4, b=2.81, g=3.02.

Crystal structure

Orpiment's unit cell
Orpiment's crystal structure consists of sheets
The sheets are stacked into layers

Gallery of orpiment specimens

Orpiment and realgar on a vuggy, quartz matrix, Nishinomaki Mine, Gunma Prefecture, Japan. Size: 5.5 x 4.0 x 3.8 cm.
El'brusskiy arsenic mine, Kabardino-Balkarian Republic, Northern Caucasus Region, Russia. Size 5.8 x 3.5 x 1.7 cm.

References

^ http://rruff.geo.arizona.edu/doclib/hom/orpiment.pdf Handbook of Mineralogy
^ http://www.mindat.org/min-3021.html Mindat.org
^ http://webmineral.com/data/Orpiment.shtml Webmineral data
^ Hooke, Robert. "Micrographia". Project Gutenberg. Retrieved 24 October 2012.
^ "Wiktionary".

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.

External links

Webexhibits "Pigments Through the Ages: Orpiment"
Babylonian Talmud Tractate Chullin see Rashi 'haZarnich' Template:He icon

[Handbook-1] ttp://rruff.geo.arizona.edu/doclib/hom/orpiment.pdf Handbook of Mineralogy

[Mindat-2] ttp://www.mindat.org/min-3021.html Mindat.org

[Webmin-3] ttp://webmineral.com/data/Orpiment.shtml Webmineral data

[4] Hooke, Robert. "Micrographia". Project Gutenberg. Retrieved 24 October 2012.

[5] "Wiktionary".

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@@ Line 47: / Line 47: @@
 | references  = <ref name=Handbook>http://rruff.geo.arizona.edu/doclib/hom/orpiment.pdf Handbook of Mineralogy</ref><ref name=Mindat>http://www.mindat.org/min-3021.html Mindat.org</ref><ref name=Webmin>http://webmineral.com/data/Orpiment.shtml Webmineral data</ref>
 }}
-'''Orpiment''', [[Arsenic trisulfide|As<sub>2</sub>S<sub>3</sub>]], 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 to 325 °C. Optically it is biaxial (−) with [[refractive index|refractive indices]] of a=2.4, b=2.81, g=3.02.
-Orpiment is an orange to yellow mineral that is found worldwide, and occurs as a sublimation product in [[volcanic]] [[fumarole]]s, low temperature [[hydrothermal]] veins, [[hot spring]]s and as a byproduct of the decay of another [[arsenic]] mineral, [[realgar]].  It is often found in association with realgar.  It takes its name from the Latin ''auripigmentum'' (''aurum'' − gold + ''pigmentum'' − [[pigment]]) because of its deep yellow color.
+Orpiment is a deep orange-yellow colored mineral, a form of arsenic sulphide that occurs worldwide. It is found in [[volcanic]] [[fumarole]]s, low temperature [[hydrothermal]] veins, and [[hot spring]]s and is formed both by sublimation and as a byproduct of the decay of another [[arsenic]] mineral, [[realgar]].  It takes its name from the Latin ''auripigmentum'' (''aurum'' − gold + ''pigmentum'' − [[pigment]]) because of its deep-yellow color.
 == Historical uses ==
-Orpiment was an important item of trade in the [[Roman Empire]] and was used as a medicine in [[China]] although it is highly toxic.  It was also used as a fly poison and to poison arrows.  Because of its striking color, it was also a favourite with [[alchemy|alchemists]] searching for a way to make gold, both in China and the West.
+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 a fly poison and to tip arrows with poison.  Because of its striking color, it was of interest to [[alchemy|alchemists]], both in China and the West, searching for a way to make gold.
-Orpiment was ground, processed and used for centuries as a [[pigment]] in painting and for sealing wax, being one of the few clear, bright yellow pigments available to artists up until the 19th century.  Orpiment presented problems, however, such as its extreme toxicity and its incompatibility with other common pigments like [[lead]] and [[copper]]-based substances such as [[verdigris]] and [[azurite]].  The use of orpiment as a pigment material ended almost entirely with the advent of the [[Cadmium pigments|cadmium yellow]]s and the various [[dye]]-based colors of the 19th century.
+For centuries, orpiment was ground down and used as a [[pigment]] in painting and for sealing wax.  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]], meant that its use as a pigment ended when [[Cadmium pigments|cadmium yellow]]s and [[dye]]-based colors were introduced during the 19th Century.
-Orpiment is also referenced in the manufacture of small [[shot]] in the 17th century by [[Robert Hooke]] in ''[[Micrographia]]'', where he transcribes an account by [[Sir Robert Moray]] to the [[Royal Society]]:<br />
+Orpiment is mentioned by [[Robert Hooke]] in ''[[Micrographia]]'' for the manufacture of small [[shot]] in the 17th century.  Hooke transcribed an account by [[Sir Robert Moray]] to the [[Royal Society]]:<br />
 : ''Take [[Lead]] out of the [[Pig]] what quantity you please, melt it down, stir and clear it with an iron Ladle, gathering together the blackish parts that swim at top like scum, and when you see the colour of the clear Lead to be greenish, but no sooner, strew upon it '''Auripigmentum''' powdered according to the quantity of Lead, about as much as will lye upon a half Crown piece will serve for eighteen or twenty pound weight of some sorts of Lead; others will require more, or less.''<ref>{{cite web|last=Hooke|first=Robert|title=Micrographia|url=http://www.gutenberg.org/files/15491/15491-h/15491-h.htm|publisher=Project Gutenberg|accessdate=24 October 2012}}</ref>
-Here the term '''Auripigmentum''' is taken to be the Latin form of Orpiment.<ref>{{cite web|title=Wiktionary|url=https://en.wiktionary.org/wiki/auripigmentum}}</ref>
+'''Auripigmentum''' here is the Latin for Orpiment.<ref>{{cite web|title=Wiktionary|url=https://en.wiktionary.org/wiki/auripigmentum}}</ref>
 == Contemporary uses ==
-Orpiment is used in the production of [[infrared]]-transmitting glass, oil cloth, linoleum, [[semiconductor]]s, [[photoconductor]]s, pigments, and fireworks.  Mixed with two parts of slaked lime, orpiment is still very commonly used in rural India as a [[Chemical depilatory|depilatory]].  It is also used in the [[tanning]] industry to remove hair from hides.
+Orpiment is used in the production of [[infrared]]-transmitting glass, oil cloth, linoleum, [[semiconductor]]s, [[photoconductor]]s, pigments, and fireworks.  Mixed with two parts of slaked lime, orpiment is still commonly used in rural India as a [[Chemical depilatory|depilatory]].  It is used in the [[tanning]] industry to remove hair from hides.
+== Technical Properties ==
+'''Orpiment''', [[Arsenic trisulfide|As<sub>2</sub>S<sub>3</sub>]], 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 to 325 °C. Optically it is biaxial (−) with [[refractive index|refractive indices]] of a=2.4, b=2.81, g=3.02.
 == Crystal structure ==