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 ?
C: The gold semi-detailed exploratory of gold and orpiment in the east of Naein (Lito-geochemical exploration 1:5000) connection consulter of Madan Ara Company in 2003 performed this project in an area with 10 [km.sup.3].
Orpiment was very common in yellow pigment in painted wall hangings throughout the 18th century and well into the 19th century too.
from Pontus near Sinope, in Egypt, the Balearic islands and the island of Lemnos), "paraetonium" (according to Pliny a "chalk" from Libya--the difference between "chalk" and "clay" was not clear to the ancient authors and not even to Agricola), "melium" (from the island of Melos, according to Pliny a white clay), green earth (creta viridis) from Smyrna, orpiment (auripigmentum) and realgar (sandaraca) from Pontus (Vitruvius, 1953, 2004, 2008).
In 1998, during large-scale open pit gold mining at Twin Creeks, Newmont Gold Corporation geologists began seeing wonderful pockets of gemmy, bright orange orpiment crystals exposed in a portion of the "South Mega Pit" called "Cut 62." Collector's Edge Minerals, Inc.
By 3000 BCE, they added red lead ([Pb.sub.3][O.sub.4]), malachite (basic copper carbonate), orpiment (arsenic trisulfide), charcoal, and red madder (from the root of the plant Rubia tinctorum).
32 Which two chemical elements are found in the minerals orpiment and realgar?
Specialists known as vendecolori (color sellers), a profession unique to Venice, played a crucial role in stimulating color experiments by introducing many new pigments, such as the yellow orpiment and reddish-orange realgar that became the signature hues of Venetian painting.
There were many others, from varieties of benzoin (the djaoui needed by popular cults in North African Islam) to galanga roots, Harmel seeds, orpiment (mineral) ...
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'.