Orpiment

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Orpiment

Orpiment, As₂S₃

Arsenic trisulfide

Arsenic trisulfide is the chemical compound with the formula ArsenicSulfur. This bright yellow solid is well known because it occurs as the mineral orpiment , has been used as a pigment, and has played a role in the analysis of arsenic compounds....
, is a common monoclinic arsenic

Arsenic

Arsenic is a well-known chemical element that has the symbol As and atomic number 33. Arsenic was first documented by Albertus Magnus in 1250....
sulfide

Sulfide

The term sulfide refers to several types of chemical compounds containing sulfur in its lowest oxidation number of −2.Formally, "sulfide" is the dianion, S2−, which exists in strongly alkaline aqueous solutions formed from H2S or alkali metal salts such as Li2S, Na2S, and K2...
mineral. It has a Mohs hardness of 1.5 to 2 and a specific gravity

Specific gravity

Specific gravity is defined as the ratio of the density of a given solid or liquid substance to the density of water at a specific temperature and pressure, typically at 4?C and , making it a dimensionless quantity ....
of 3.46. It melts at 300 °C to 325 °C. Optically it is biaxial (-) with refractive indices

Refractive index

The refractive index of a medium is a measure for how much the speed of light is reduced inside the medium. For example, typical soda-lime glass has a refractive index of 1.5, which means that in glass, light travels at times the speed of light in a vacuum....
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 fumaroles, low temperature hydrothermal veins, hot springs

Hot Springs

Hot Springs may refer to:* Hot Springs, Arkansas* Hot Springs, Montana* Hot Springs, North Carolina* Hot Springs, South Dakota* Hot Springs, Virginia...
and as a byproduct of the decay of another arsenic

Arsenic

Arsenic is a well-known chemical element that has the symbol As and atomic number 33. Arsenic was first documented by Albertus Magnus in 1250....
mineral, realgar

Realgar

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Encyclopedia

Orpiment, As₂S₃

Arsenic trisulfide

Arsenic

Arsenic is a well-known chemical element that has the symbol As and atomic number 33. Arsenic was first documented by Albertus Magnus in 1250....
sulfide

Sulfide

Specific gravity

Refractive index

Hot Springs

Arsenic

Arsenic is a well-known chemical element that has the symbol As and atomic number 33. Arsenic was first documented by Albertus Magnus in 1250....
mineral, realgar

Realgar

Realgar, Polymorphism -As4S4, is an arsenic sulfide mineral. It is a soft, sectile mineral occurring in monoclinic crystals, or in granular, compact, or powdery form, often in association with the related mineral, orpiment ....
. It is often found in association with realgar. It takes its name from the Latin auripigmentum (aurum - gold + pigmentum - pigment

Pigment

A pigment is a material that changes the color of light it Reflection as the result of selective color absorption. This physical process differs from fluorescence, phosphorescence, and other forms of luminescence, in which the material itself emits light....
) because of its deep yellow color.

Orpiment is also known as "King's Yellow", "Chinese Yellow" and "Yellow Orpiment" .

Historical uses

It was an important item of trade in the Roman Empire

Roman Empire

The Roman Empire was the Roman Republic phase of the Ancient Rome, characterised by an autocracy form of government and large territorial holdings in Europe and around the Mediterranean....
and was used as a medicine in China

China

China is a Culture of China, an ancient civilization, and, depending on perspective, a national or multinational entity extending over a large area in East Asia....
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 alchemists

Alchemy

Alchemy , a part of the Occult Tradition, is both a philosophy and a practice with an aim of achieving ultimate wisdom as well as immortality, involving the improvement of the alchemist as well as the making of several substances described as possessing unusual properties....
searching for a way to make gold, both in China and the West.

Orpiment was ground, processed and used for centuries as a pigment

Pigment

A pigment is a material that changes the color of light it Reflection as the result of selective color absorption. This physical process differs from fluorescence, phosphorescence, and other forms of luminescence, in which the material itself emits light....
in painting, 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

Lead

Lead is a main-group Chemical element with symbol Pb and atomic number 82. Lead is a soft, malleable poor metal, also considered to be one of the heavy metal ....
and copper

Copper

Copper is a chemical element with the symbol Cu and atomic number 29.It is a ductile metal with very high thermal and electrical conductivity....
-based substances such as verdigris

Verdigris

Verdigris is the common name for the green coating or patina formed when copper, brass or bronze is weathered and exposed to air or seawater over a period of time....
and azurite

Azurite

Azutite may also refer to a blue Green fluorescent protein#GFP derivatives.----Azurite is a soft, deep blue copper mineral produced by weathering of copper ore deposits....
. The use of orpiment as a pigment matter ended almost entirely with the advent of the cadmium

Cadmium

Cadmium is a chemical element with the symbol Cd and atomic number 48. A relatively abundant , soft, bluish-white, transition metal, cadmium is known to cause cancer and occurs with zinc ores....
yellows and the various dye

Dye

A dye can generally be described as a colored substance that has an Chemical affinity to the Wiktionary:substrate to which it is being applied....
-based colors of the 19th century.

Contemporary uses

It is presently used in the production of infrared

Infrared

Infrared radiation is electromagnetic radiation whose wavelength is longer than that of visible light , but shorter than that of terahertz radiation and microwaves ....
-transmitting glass, oil cloth, linoleum; in semiconductor

Semiconductor

A semiconductor is a material that has electrical conductivity between those of a Electrical conductor and an electrical insulation; it can vary over that wide range either permanently or dynamically....
s and photoconductors, as a pigment and in fireworks. Mixed with two parts of slaked lime, orpiment is still very commonly used in rural India as a depilatory

Chemical depilatory

A chemical depilatory is a cosmetic preparation used to remove the hair from the skin on the human body. Currently, a common active ingredient is Thioglycolic acid, which breaks down the disulfide bonds in keratin and weakens the hair so that it is easily scraped off where it emerges from the hair follicle....
. It is also used in the tanning

Tanning

Tanning is the process of making leather, which does not easily Decomposition, from the skins of animals, which do. Often this uses tannin, an acidic chemical compound....
industry to remove hair from hides.

Orpiment

Historical uses

Contemporary uses

Crystal structure

Image gallery

Footnotes

External links