Pararealgar
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Pararealgar is an arsenic sulfide material with the chemical formula AsS. It forms gradually from realgar under exposure to light. Its name derives from the fact that its elemental composition is identical to realgar, As4S4. It is soft with a Mohs hardness of 1 - 1.5, is yellow orange in colour, and its monoclinic or prismatic crystals are very brittle, easily crumbling to powder.