Realgar
The realgar is a orange Minéral red, composed of Sulfure of Arsenic of formula As4S4; the crystals (Monoclinical S) are rare.
The word would come from Arabic “ rhag Al-ghar ” (dust of cave), or from “ rhag Al-far ” (powder of the rats) because of a misreading: realgar was actually used as rat poison; it was also employed in Pyrotechnie or for the realization of Enluminure S like Pigment coloured yellow or red, used by the painters until the end of the 19th century.
Under the action of the light, realgar tends to deteriorate in pararéalgar, of which the structure is very similar to that of the Orpiment (As2S3). Research of years 1980 of Roberts and Al made it possible to raise ambiguities between these two materials. Indeed, orpiment cannot be thermodynamically formed starting from realgar if the pressure of S2 (G) is too low, which is the case in the terrestrial atmosphere.
Layers
Although not very frequent, realgar is an important arsenic ore.In France, realgar was announced in Houillère S of the Massif Central and with Holy-Marie-with-Mines (Alsace), where it is associated with native arsenic and other arsenical minerals.
| Random links: | Roger Ier de Fézensaguet | Jean-Luc Marion | Mario Sbaletta | Maximilien Merveldt | Phoebe Holcroft Watson | Banlieue_noire_de_Dennison,_Pennsylvanie |