Is arsenicum sulphide with formula As4S4 and hardness of 1.5.
It must be stored far from light because it may contain traces of other minerals like arsenolite,orpiment,pararealgar; these minerals are sensitive to light and may cause a deterioration.
Very difficult to cut due to it's low hardness and heat sensitivity due to sulphur.In addition to that the crystal has often tube inclusions ( realgar is hydrothermal mineral ),therefore the cutting and polishing result is not the best you may think,but this is it...Some niches or natural cavities may be seen of surface.Untreated.
It comes from Sukhonkoe (Au-Hg) Mine, Altai Krai, South Siberia, Russia
Size: 7.2x7.1x3.9 mm.
Weight: 1.25 ct.