REALGAR (AURIPIGMENT)

Realgar, also referred to as arsenic blende, ruby sulfur, or ruby of arsenic, is a mineral composed of arsenic sulfide with the chemical formula α-As4S4. This soft and sectile mineral typically forms in monoclinic crystals or appears in granular, compact, or powdery forms, often found alongside the related mineral orpiment (As2S3). Characterized by its orange-red hue, realgar melts at 320 °C and burns with a bluish flame, emitting arsenic and sulfur fumes. It has a Mohs hardness ranging from 1.5 to 2 and a specific gravity of 3.5, with an orange streak. Realgar is trimorphous, existing in forms such as pararealgar and bonazziite.

TOXIC, DO NOT EXPOSE TO LIGHT (DESINTEGRATES)