Is a rare mineral usually forms with realgar. Is a Arsenic Sulfide with formula As2S3, hardness 1.5-2. Normally is found as incrustation or alteration of realgar, it must be kept at dark or the sun light will turn after long time into powder. So, good crystals suitable for cutting are not common and faceting /polishing this material is not an easy task.
This gem has been cut from Chinese material.
Size: 8.5x6.8x3.8 mm.
Weight: 1.15 ct.