Realgar and Orpiment

Orange Realgar and lemon-yellow Orpiment intertwined with one another incrusting on a white rhombohedron Calcite. Realgar (AsS) is a deep red to orange mineral that becomes more yellow when exposed to light. Lustre can be resinous, adamantine or dull and streak is orange-yellow. Hardness is 1 1/2 to 2 and cleavage is good lengthwise. Realgar is usually prismatic but can also be granular, earthy, incrusting or disseminating. Orpiment (As2S3) is a lemon-yellow or orange coloured mineral with a resinous lustre that is pearly on the cleavage. Streak is lemon-yellow and hardness is 1 1/2 to 2. Cleavage is good in one direction. Orpiment can be poorly formed crystals but they are rare, usually found as foliated, granular or earthy incrustations.