Realgar


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Related to Realgar: arsenopyrite

realgar

[rē′al‚gär]
(mineralogy)
AsS A red to orange mineral crystallizing in the monoclinic system, having a resinous luster and found in short, vertical striated crystals; specific gravity is 3.48, and hardness is 1.5-2 on Mohs scale. Also known as red arsenic; red orpiment; sandarac.

Realgar

 

a mineral, arsenic monosulfide (AsS); contains 70.1 percent arsenic.

Realgar has a complex crystal structure. The lattice is constructed of individual As4S4 molecules, with the sulfur ions forming a square, and the arsenic ions a tetrahedron; the centers of the square and tetrahedron coincide. Realgar crystallizes in the monoclinic system, forming bright orange-red prismatic crystals. It occurs most commonly in the form of compact granular masses or powdery, earthy aggregates. The mineral has a density of 3,560–3,590 kg/m3 and is sectile; its hardness is 1.5–2 on Mohs’ scale.

Realgar is usually found together with orpiment, stibnite, and lead, silver, and gold ores of hydrothermal origin but may also occur as a sublimation product of volcanic eruptions or as a deposit from hot springs. When exposed to sunlight, it decomposes into orange to lemon-yellow orpiment, As2S3. Realgar is an important ore for the extraction of arsenic. In the USSR, deposits of realgar are found in Transcaucasia; there are also major deposits in such countries as Czechoslovakia, Rumania, Greece, the USA, and Japan.

References in periodicals archive ?
The most densified free-volume structure is character for REA2, composed of [alpha]-[As.sub.4][S.sub.4] polymorph (mineral realgar as a source for milling).
Daily dose of 0.1 g realgar was maintained during the course of treatment in group A, while it was increased by 0.1 g each time until the blood arsenic concentrations were more than 20 [micro]g/L in group B.
Realgar and the Double Fifth are commonly associated with the expulsion of demons, while cinnabaris, croton seed, and red bean appear in later imperial medical texts mentioned as curing agents for gudu in general.
Wu et al., "Metabolic profiling studies on the toxicological effects of realgar in rats by [sup.1]HNMR spectroscopy," Toxicology and Applied Pharmacology, vol.
Chinese people prepare and eat Zong Zi, drink realgar wine and race dragon boats on that day.he festival falls on June 23 this year.
We identified realgar in soils 1, 3, 4, and 11 and arsenopyrite in soils 4 and 7.
Corriente remite a realgar y dice que ambas "son evoluciones semanticas de la acepcion del estandar, q.
Tony was also offering picropharmacolite with realgar from the White Caps mine, Manhattan, Nye County, Nevada.
A Chinese text from the 9th century describes how a mixture of sulfur, realgar (sulfur and arsenic), saltpeter, and honey ignited when heated.
(9) Combustions: burning flames, torches, goats, shooting-stars, ejected shooting stars, aurora borealis (blood-red colors, chasms), comets (tracking and trailing), milky way; condensations: upper (rain, snow, hail), lower (dew, frost); emanations: rivers (from the various mountains), interchange of sea and land, sea (source and salinity), winds (from the various points of the compass), earthquakes, tidal waves; violent atmospheric phenomena: thunder, lightening, hurricanes, whirlwinds, firewinds and thunderbolts; reflections: haloes, rainbows, sun-dogs, mock-suns and rods; minerals: realgar, ochre, ruddle, sulphur, cinnabar; metals: iron, gold, copper.
Such are the kinds of stones that cannot be melted, and realgar, and ochre, and ruddle, and sulphur [...], most things quarried being either coloured lye or, like cinnabar, a stone compounded of it.
32 Which two chemical elements are found in the minerals orpiment and realgar?