Sulfides: realgar
Diagnostic Card.
As S
Crystal system monoclinic
Hardness of 1.5-2
The share of 3,5-36
Cleavage distinct
fracture conchoidal
Colour red, red-orange
The color in yellow-orange powder
Gloss resin
Fluorescence missing
Realgar crystals occur quite often have a prismatic shape, with shading in elongation. The most common mineral forms a crust or grainy mass. In the fresh form it is transparent or translucent. The color and the intensity of red or orange-red. The line on a porous porcelain yellow-orange. Gloss varies from resin to fat. Very soft and quite heavy. Cleavage is distinct, but not perfect. Fracture conchoidal; mineral may be tonkoplastinchatym.
Chemical composition. Arsenic (As) 70,1%, cepa (S) 29,9% (Wed with orpiment). form crystals. For the most part is short-crystals. Class symmetry. Prismatic-2 / m. Cleavage. Perfect for (010) (210). Aggregates. The dense, fine-grained, drain.
Diagnostic features.
As a result of prolonged exposure to light, realgar easily destroyed, turning into orange-yellow powder, which consists mainly of a very poisonous arsenolita and orpiment and pararealgara. Easily melts and evaporates (emitting the smell of garlic), in cones a red sublimate. It dissolves in aqua regia with the release of sulfur.
Origin.
It is present mainly in the low-temperature hydrothermal veins, associating with the sulfides of arsenic and antimony. It may also be formed by volcanic sublimation, in the fumaroles. Furthermore, realgar formed near hot springs. Finally, it is present in some sedimentary rocks (dolomite, bituminous shales). Mainly found in low-temperature hydrothermal veins, satellites - orpiment and stibnite; at least - as the volcanic sublimation product among solfataras and discharge from the hot springs.
Place of Birth.
This mineral is known in various parts of Italy. Most crystals come from the famous deposits Lengenbah, Valle di Binn, Vallesian (Switzerland).
Application.
Realgar used to produce metallic arsenic and its various compounds. In the past, mixed with nitrate it was used for the production of artificial lights in pyrotechnics.
Realgar, orpiment, galena, quartz. Palomo district to, Castrovirreyna prov., Huancavelica Lep., Peru.
Toxic and hazardous radioactive rocks and minerals
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** - Radioactive rocks and minerals (obligatory check on a regular dosimeter + ban on the open sale of radioactivity in the event of more than 24 mR / hour + additional measures to protect the population)
Catalog minerals and gems in groups of the world
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