Orpiment

Orpiment prepared as a paint pigment

Orpiment is a common monoclinic crystalline mineral Orpiment (Arsenic trisulfide) Source: US Government File history Legend: (cur) = this is the current file, (del) = delete this old version, (rev) = revert to this old version. ... Orpiment (Arsenic trisulfide) Source: US Government File history Legend: (cur) = this is the current file, (del) = delete this old version, (rev) = revert to this old version. ... Sample of orpiment ground and processed as a pigment, painted on paper prepared by Palladian This image has been released into the public domain by the copyright holder, its copyright has expired, or it is ineligible for copyright. ... Sample of orpiment ground and processed as a pigment, painted on paper prepared by Palladian This image has been released into the public domain by the copyright holder, its copyright has expired, or it is ineligible for copyright. ...

• Chemical Composition: As₂S₃, arsenic trisulfide

• Molecular Weight: 246.04 gm

• Hardness: 1.5-2

• Optical refractive index: Biaxial (-), a=2.4, b=2.81, g=3.02

Orpiment is a mineral that is found world-wide, and occurs as a sublimation product in volcanic fumaroles, low temperature hydrothermal veins, hot springs 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. The refractive index of a material is the factor by which electromagnetic radiation is slowed down (relative to vacuum) when it travels inside the material. ... Sulfur deposits near a fumarole A fumarole (Latin fumus, smoke) is an opening in Earths (or any other astronomical bodys) crust, often in the neighborhood of volcanoes, which emit steam and gases such as carbon dioxide, hydrochloric acid, and hydrogen sulfide. ... Hydrothermal circulation in the oceans is the passage of the water through mid-ocean Ridge (MOR) systems. ... Green Dragon Spring at Norris Geyser A hot spring is a place where warm or hot groundwater issues from the ground on a regular basis for at least a predictable part of the year, and is significantly above the ambient ground temperature (which is usually around 55~57°F or... General Name, Symbol, Number arsenic, As, 33 Chemical series metalloids Group, Period, Block 15, 4, p Appearance metallic gray Atomic mass 74. ... Orpiment and Realgar Realgar is a mineral of arsenic sulfide, AsS. Realgar, orpiment, and arsenopyrite provide nearly all the worlds supply of arsenic as a byproduct of smelting concentrates derived from these ores. ... In biology, pigment is any material resulting in color in plant or animal cells which is the result of selective absorption. ...

Orpiment was ground, processed and used for centuries as a pigment 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 and copper-based substances such as verdigris and azurite. The use of orpiment as a pigment matter ended almost entirely with the advent of the cadmium yellows and the various dye-based colors of the 19th century. In biology, pigment is any material resulting in color in plant or animal cells which is the result of selective absorption. ... General Name, Symbol, Number lead, Pb, 82 Chemical series poor metals Group, Period, Block 14, 6, p Appearance bluish white Atomic mass 207. ... General Name, Symbol, Number copper, Cu, 29 Chemical series transition metals Group, Period, Block 11, 4, d Appearance copper, metallic Atomic mass 63. ... Verdigris is the common name for the chemical Cu(CH3COO)2. ... Azurite Azurite ground as a pigment Azurite is a carbonate mineral with chemical composition Cu3(CO3)2(OH)2, (copper carbonate hydroxide). ... General Name, Symbol, Number cadmium, Cd, 48 Chemical series transition metals Group, Period, Block 12, 5, d Appearance silvery gray metallic Atomic mass 112. ... A dye can generally be described as a coloured substance that has an affinity to the substrate to which it is being applied. ...

Orpiment is also known as "King's yellow"

See also: list of minerals Gem animals. ...

External links

• "Mindat.org: Orpiment"
• "Webmineral.com Mineralogy Database: Orpiment"
• "Webexhibits "Pigments Through the Ages" : Orpiment"