|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]|
an important ore of arsenic, a red or orange mineral containing both arsenic and sulfur. Typically it is a minor constituent of ore veins in association with orpiment (into which it disintegrates on long exposure to light). Realgar has been used by the Chinese for carvings, but these also deteriorate under light. It forms prismatic crystals of monoclinic symmetry. For detailed physical properties, see sulfide mineral (table)
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