Realgar, α sulfide mineral, also known as "ruby sulphur" or "ruby of arsenic". It is a soft, sectile crystals, or in granular, compact, or powdery form, often in association with the related mineral, orpiment (As2S3). It is orange-red in color, melts at 320 °C, and burns with a bluish flame releasing fumes of arsenic and sulfur. Realgar is soft with a Mohs hardness of 1.5 to 2 and has a specific gravity of 3.5. Its streak is orange colored. It is trimorphous and bonazziite Its name comes from the Arabic rahj al-ġār (رهج الغار, "powder of the mine"), via Catalan, and its earliest record in English is in the 1390s.