Orpiment


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Related to Orpiment: arsenic, cinnabar

orpiment

[′ȯr·pə·mənt]
(mineralogy)
As2S3 A lemon-yellow mineral, crystallizing in the monoclinic system, and generally occurring in foliated or columnar masses; luster is resinous and pearly on the cleavage surface, hardness is 1.5-2 on Mohs scale, and specific gravity is 3.49. Also known as yellow arsenic.

Orpiment

 

arsenic trisulfide, AS2S3. Orpiment contains 60.91 percent arsenic and 39.09 percent sulfur. It has a monoclinic system. The crystals are prismatic; rodlike and columnar aggregates, as well as powdery, nodular, and clustered bodies, are characteristic. Orpiment is easily cut with a knife. Its color ranges from golden- and lemon-yellow to orange-yellow, sometimes brownish. Its luster is oily to diamondlike; on the cleavage planes it is like mother-of-pearl, semimetallic, and tarnishes rapidly. Its hardness on the mineralogical scale is 1.5–2. Its density is 3,490 kg per cu m. It is soluble in aqua regia and bases. It is a nonconductor and diamagnetic. During heating it becomes red. Orpiment is found in low-temperature, hydrothermic deposits in association with realgar, antimony, and other substances, as well as in deposits of hot mineral springs and in volcanic encrustations. It is the raw material from which arsenic compounds are obtained.

A. B. PAVLOVSKII

orpiment

An arsenic sulfur compound; used in paints as a yellow pigment.
References in periodicals archive ?
It included not only painters' pigments such as azurite, vermilion, and orpiment, but also raw materials used in a variety of crafts.
Orpiment was found in the flesh tones, vermilion in the red robe of the youth tearing off his cloak to follow Alfred, and Prussian blue was used for the sky.
Titian, a citizen of mercantile Venice, exalted in the materially sumptuous, including rare pigments (lapis lazuli from central Asia, transalpine azurite, orpiment, dyers' red lake which he sent for when in Augsburg by the half-pound, and the local vermilion and unsurpassed lead white) which trade brought to the wharves on the 'precious strand' of the Republic that 'once did hold the gorgeous East in fee'.
Alteration includes carbon/pyrite (shaley units) and orpiment, massive grey sulphide- bearing silica cut by multiple events of quartz veining.
Arsenic market is a highly dependent segment of the global economy - the material is recovered from processing of nonferrous ores or concentrates and is a byproduct of gold mining from orpiment and realgar.