realgar

re·al·gar

R0070100 (rē-ăl′gär′, -gər)n. A soft orange-red arsenic ore, As₂S₂, used in pyrotechnics and tanning and as a pigment.

[Middle English, from Medieval Latin, from Catalan, from Arabic rahj al-ġār, powder (of) the mine or cave : rahj, powder + al-, the + ġār, cave; see ġrr in Semitic roots.]

realgar

(rɪˈælɡə) n (Minerals) a rare orange-red soft mineral consisting of arsenic sulphide in monoclinic crystalline form. It occurs in Utah and Romania and as a deposit from hot springs. It is an important ore of arsenic and is also used as a pigment. Formula: AsS[C14: via Medieval Latin from Arabic rahj al-ghar powder of the mine]

re•al•gar

(riˈæl gər, -gɑr)

n. an orange-red mineral, arsenic sulfide, AsS, found in granular and crusty masses and also produced artificially for use in pyrotechnics. [1350–1400; Middle English < Medieval Latin realger « Arabic rahj al-ghār powder of the mine or cave]

Thesaurus

Noun

realgar - a rare soft orange mineral consisting of arsenic sulphide; an important ore of arsenicAs, atomic number 33, arsenic - a very poisonous metallic element that has three allotropic forms; arsenic and arsenic compounds are used as herbicides and insecticides and various alloys; found in arsenopyrite and orpiment and realgarmineral - solid homogeneous inorganic substances occurring in nature having a definite chemical composition

Translations

Realgar

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.

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Words related to realgar

noun a rare soft orange mineral consisting of arsenic sulphide

Related Words